ACUS01 KWNS 241251
SWODY1
SPC AC 241249

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Sat Aug 24 2024

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR
CORNERS REGION NORTHEASTWARD INTO THE CENTRAL HIGH PLAINS...OVER
PARTS OF MISSOURI TO NORTHERN ARKANSAS...AND ALSO OVER AND NEAR
WESTERN OKLAHOMA...

...SUMMARY...
Strong to locally severe storms are possible today from the Four
Corners region northeastward into the central High Plains, over
parts of Missouri to northern Arkansas, and also over and near
western Oklahoma.

...Synopsis...
Positively tilted mid/upper-level troughing should shift slowly
eastward through the period, from the West Coast States to the
northern Rockies, Great Basin and southern CA. Several shortwaves
will pivot through the associated tightly cyclonic regime astride
the trough, then eject into the downstream southwest flow.
Additional perturbations will move northeastward in continuing
southwest flow over the southern Rockies and central Plains, closer
to a pronounced anticyclone whose 500-mb high should move slowly
northeastward over OK. Ridging accompanying that high should build northeastward to southern Hudson Bay by the end of the period. A
broad fetch of deep-layer moisture was apparent in moisture-channel
imagery and surface analysis from northwestern MX across the Four
Corners to the central Rockies and adjacent High Plains.

Otherwise, the 11Z surface chart showed a long-lived,
quasistationary frontal zone from Atlantic waters off the Carolinas, southwestward over northern FL, to coastal LA, then northwestward as
a warm front across southern/western OK to a low near DDC. Rich
moisture has spread through the front over central eastern OK and
into southern/central KS, with upper 60s and greater surface
dewpoints. The low is expected to move/redevelop into the
north-central KS/south-central NE vicinity by 00Z, with warm
frontogenesis to its east across the southern IA/northern NE area.
A separate cold front -- analyzed from eastern MT southwestward over northwestern UT and southern NV -- should move slowly eastward
through the period, reaching the western Dakotas, central WY and
southwestern UT by 12Z tomorrow.

...Four Corners to Central High Plains...
Again today, the persistent monsoonal moisture plume (somewhat eastward-displaced from previous days) should host widely scattered
to scattered thunderstorms by mid/late afternoon. Activity should
move northward to northeastward over this corridor, with isolated
severe gusts being the main concern, and hail near severe limits
possible over the High Plains portion of the outlook area.

Diurnal heating of higher terrain from just south of I-40 across the
Four Corners, San Juans, and assorted ranges from there to the
Laramies and Front Range, should remove MLCINH quickly into early
afternoon, fostering deep convective growth. Effective shear will
be modest (generally 30 kt or less) due to a lack of both
1. Stronger/backed near-surface flow and
2. Greater CAPE density and buoyant depth (related to modest lapse
rates aloft in the monsoonal plume).
Still, the southeastern fringe of the mass response in upper levels
to the Western CONUS troughing should yield enough cloud-layer shear
for a few organized multicell storms, with translational vector
augmentation of outflow winds possibly contributing to marginal
severe potential. The main supporting factor for downdraft
intensity will be a well-mixed subcloud layer beneath around 200-800
J/kg ambient MLCAPE.

...MO/AR...
An MCV was apparent in composited radar imagery over southeastern NE
between LNK-FNB, and should pivot slowly southeastward through the
day. Associated regionally enhanced low-level moist/warm advection,
and isentropic lift to LFC, have been supporting swath of elevated
convection now over portions of northwestern MO. Lightning coverage
and cooling IR cloud tops have been noted the past hour in a roughly north/south-oriented band of embedded thunderstorms, though
radar-reflectivity structures remain messy and disorganized.

Further organization/intensification with a southward translational
thrust is possible through the day, as a combination of surface
heating and boundary-later warm/moist advection combine to
destabilize the foregoing airmass. This will lead to at least
isolated potential for damaging gusts and marginally severe hail.
Guidance still varies considerably on the potential for this
activity to merge upscale enough for a single, well-developed cold
pool, which would create a greater conditional wind threat over
parts of west-central/southwestern MO and perhaps into northern AR
before encountering decreasing instability. Southern parts of the
outlook area have been extended somewhat, and the area widened
somewhat, to account for these mesobeta- to convective-scale
uncertainties.

...Western OK and vicinity...
Isolated to widely scattered thunderstorms are possible from mid-
late afternoon, with a few perhaps straying into early evening,
offering locally strong-severe microbursts.

A surface moist/buoyancy axis will persist under and near the
mid/upper high, across southern to northeastern OK and into eastern
KS. West of the associated moisture plume, an effective dryline
will set up by midafternoon from northwest TX to northwestern OK,
representing a differential between more intense heating/mixing to
the west and the more strongly capped, moist boundary-layer
environment under and nearer the high aloft. That boundary also
should conform closely to a wind-shift line and confluence/
convergence axis, west of which winds at the surface will have a
substantial westerly component. With further westward extent into
the Panhandles, the boundary layer will be too dry to support
substantial convection. Within the transition zone, represented by
the outlook area, just enough moisture should be present to support
a minimally capped, deep, hot, well-mixed boundary layer with around
250-1000 J/kg MLCAPE and DCAPE values commonly 1000-2000 J/kg. the
dryline should retreat northwestward through the area this evening,
but under unfavorably strong (and intensifying) MLCINH, and without
appreciable large-scale support, later development is not expected.

..Edwards/Bentley.. 08/24/2024

$$
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ACUS01 KWNS 251257
SWODY1
SPC AC 251256

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0756 AM CDT Sun Aug 25 2024

Valid 251300Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
FOUR CORNERS TO SOUTHWESTERN WYOMING...AND OVER PORTIONS OF WESTERN
MINNESOTA AND THE EASTERN DAKOTAS...

...SUMMARY...
Severe gusts and hail are most probable today over parts of the Four
Corners to southwestern Wyoming, and this evening over portions of
western Minnesota and the eastern Dakotas.

...Synopsis...
A seasonally well-amplified mid/upper-level pattern will persist
over the CONUS, but with some important changes due to the
progression of embedded synoptic- to subsynoptic-scale features. An intermittently closed cyclone now over north-central NV will eject
slowly northeastward to southeastern ID through the period, while
devolving to an open-wave trough. By 12Z tomorrow, the full trough
should extend from the MT Rockies southward through the remnant
low's vorticity max, then southwestward to southern NV.

Meanwhile, a broad anticyclone -- initially centered over northern
OK/southern KS -- will move northeastward, with the 500-mb high over
central MO by 12Z, and ridging north-northeastward across Lake
Superior. The northward component of this shift should occur partly
in response to a well-defined low/trough in the subtropical
easterlies, now evident over the north-central to southwestern Gulf.
This feature should move ashore on the lower/middle TX Coast around
the end of the period. Northeast of the high, a strong shortwave
trough now over northwestern QC will dig south-southeastward through
tonight, reaching the St. Lawrence Valley and approaching northern
NY by 12Z.

At the surface, 11Z analysis showed a persistent, very slowly
frontolytic, quasistationary boundary from just offshore of the
Carolinas to the north-central Gulf Coast, becoming a diffuse warm
front over astern parts of TX/OK. Rich low-level moisture has
returned northward near this boundary in OK/AR and farther north
across parts of the central/northern Plains. A low was drawn north
of MIB, with cold front southwestward across the northwestern corner
area of SD, into north-central WY. By 00Z, the front should reach
from near the MN/ND/MB border confluence across the eastern Dakotas,
parts of north-central/southwestern NE and near CYS. The front
should proceed overnight to a 12Z position from northeastern MN to
the FSD/SUX vicinity, central NE and eastern CO.

...Northern Plains/Upper Midwest...
Scattered thunderstorms are expected to develop along/ahead of the
cold front -- predominantly after 00Z, though enough moistening/
heating may occur for isolated late-afternoon development.
Supercells and bowing lines/clusters will be possible, offering
large hail and severe gusts.

Activity should occur as the front encounters what is left of a
diurnally well-heated and still-unstable boundary-layer airmass,
with only minimal diabatic cooling, due to the presence of rich
moisture near the surface, Surface dewpoints already are commonly
in the 70s F in a swath of the warm sector with 11Z axis from
north-central ND south-southeastward across eastern portions of
SD/NE/KS and the Arklatex region. Forecast soundings indicate the
moist layer should deepen through the day beneath strong capping,
and steep midlevel lapse rates. With a deep troposphere still
present over this area, atop the favorably unstable boundary layer,
MLCAPE in the 3000-4000 J/kg range will be possible. This will be
collocated with slowly strengthening flow aloft, such that 30-45-kt effective-shear magnitudes will be possible from late afternoon
through the evening.

...Central/southern Rockies and vicinity, south-central Plains...
Scattered showers and thunderstorms, with at least isolated
strong-severe gust potential, should become common by this afternoon
in a vast, roughly triangular area in and near the outlook, from
western NM and eastern AZ to parts of southeastern MT and southern
KS. Within that area, the greatest potential for severe should be
on the western fringes, with supercells and bowing clusters possible
in a corridor spanning portions of the Four Corners area to
southwestern WY. In that region, the greatest diurnal
destabilization will overlap the most favorable deep-layer lapse
rates, and strengthening vertical shear ahead of the progressive
western trough.

Mid/upper-level moisture-channel imagery, available GPS PW data, and
surface analysis show a persistent plume of deep-layer monsoonal
moisture, maintaining some continuity from the ITCZ well south of
mainland MX, across parts of west-central MX and Chihuahua, to NM,
CO, WY and western NE. Enough low-level moisture (PW above 1 inch
in some areas) to support organized convective potential extends
farther westward over the Four Corners area, especially into
northeastern AZ, eastern UT and western CO. Forecast soundings in
that corridor show favorable deep shear for supercells, with
effective-shear magnitudes in the 40-55-kt range, and elongated,
rather straight low/middle-level hodographs favoring a large-hail
threat, in addition to the broader severe-gust potential.

Farther east, much of the higher terrain across the "marginal" area
will reach convective temperature relatively early in the
diurnal-heating cycle, with little CINH, resulting in abundant
development, slowing the pace of additional destabilization. Still,
isolated strong/briefly severe gusts may occur, especially where north-northeastward moving clusters of convection encounter pockets
of well-mixed boundary layer suitable for intense downdrafts.
Farther east onto the High Plains, more-favorable heating/mixing
will occur, but with weak shear nearer to the mid/upper high.

..Edwards/Bentley.. 08/25/2024

$$
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ACUS01 KWNS 271256
SWODY1
SPC AC 271254

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0754 AM CDT Tue Aug 27 2024

Valid 271300Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT
LAKES REGION AND PORTIONS OF THE MIDWEST...

...SUMMARY...
Clusters of damaging thunderstorm winds and occasional large hail
are possible across the Great Lakes region and portions of the
Midwest.

...Synopsis...
The mid/upper-level pattern temporarily will become less amplified
over the CONUS, as an anticyclone now over the mid Mississippi
Valley region weakens, and a nearly zonal northern stream takes
shape across most of the northern tier of states. This will occur
downstream from a strong synoptic-scale cyclone -- evident in
moisture-channel imagery over southwestern/near-coastal BC. The
500-mb low should move east-southeastward to the northern Rockies by
12Z tomorrow, with trough and cyclonic flow southward to the
northern Great Basin. Downstream, a strong shortwave trough was
apparent over the western Dakotas to the NE Panhandle, with embedded circulation center near DIK. This perturbation is forecast to
deamplify gradually, but still remain a well-defined shortwave
trough, as it moves eastward to the Lake Superior/northern Lake
Michigan region by the end of the period.

At the surface, 11Z analysis showed a low near the end of the
Keweenaw Peninsula in Upper MI, with cold front extending diffusely southwestward through post-outflow air across northern WI, southern
MN, central NE, to parts of western KS and eastern CO. The Great
Lakes low should migrate eastward along the front to ME by 12Z
tomorrow. The front is expected to reach Lake Huron, central Lower
MI, southeastern WI, northern MO, central KS, and southwestern CO by
00Z, preceded by several outflow boundaries. By 12Z, the front
should extend from the ME low across central/western NY, Lake
Ontario, northern IN, and central MO, becoming quasistationary from
there to central KS, and a warm front over eastern CO. The latter
will occur in response to return flow setting up ahead of the
Northwest cyclone aloft, with strengthening lee troughing between
the front and a low over eastern MT. That low will be attached to
another, stronger cold front emerging from the Rockies, and moving
eastward over central/southwestern MT by 12Z.

...Great Lakes to central Plains...
Widely scattered to locally numerous thunderstorms (in episodic
clusters) are expected to cross the outlook area through the period,
offering damaging to severe gusts, occasional large hail, and a
marginal tornado threat. Within the broader 15%/"slight risk" area,
one or more corridors of greater severe-wind threat may develop in
concert with the best-organized portions of any cold-pool-driven, forward-propagational complex(es) that may develop. However,
specific tracks of such axial maxima are still too uncertain at this
time, due to dependence on iterative mesoscale factors.

A residual arc of thunderstorms over Lake Huron and southeastern
Lower MI has left an outflow boundary across southern Lower MI to
south-central WI to near the southeast tip of MN, where it is being
intercepted from the west by fresh outflow from another complex
moving northeastward over western WI. The relatively stable airmass
north of the first MCS' outflow boundary is shallow and subject to destabilization from both warm advection and (later this morning)
diurnal heating, lending some potential for expansion or
intensification of any part of the WI complex that still is present
and extends into the increasingly favorable theta-e. Meanwhile, the
outflow in/from the second ongoing complex may:
1. Produce isolated severe gusts through the shallow stable outflow
layer over WI in the near term,
2. Modify favorably across parts of WI/IL/lower MI today (the
latter assuming it reaches Lower MI to reinforce the first outflow
pool) and
3. Focus additional development an uncertain distance farther south
-- possibly including upscale growth into more complex(es), today
into this evening.

Overall, the environment along and south of the outflow boundaries
should be favorable thermodynamically, with strong diabatic heating
and rich moisture (70s F surface dewpoints being common). In
satellite imagery, a plume of moisture with origins in the Southwest
monsoon -- and still connected to MCS activity in western MX --
extends near an ELP-CAO-GLD-FSD axis. A residual EML to the east of
this, and around the northwestern quadrant of the anticyclone,
results in a plume of warmer 700-mb temperatures (per last night's
00Z charts and available soundings so far this morning), as well as
somewhat steeper midlevel lapse rates and slightly stronger capping
atop the moist boundary layer. This contributes to the potential
for areas of 3000-4500 J/kg MLCAPE along and south of the
boundary(s) from parts of WI and Lower MI southwestward into
northern MO. While such strong buoyancy will support upscale
growth, longevity of clusters also is uncertain due to lack of a
supportive LLJ.

This far southeast of the main mid/upper-level shortwave trough,
flow aloft and deep shear will be rather weak, so steering flow will
be less of an influence on convective motion than internal cold
pools and foregoing mesoscale boundary alignment. Farther
southwest, nearer to the cold front over the lower Missouri Valley
into KS, shear and CAPE both will be weaker, but still with enough
instability to support isolated to scattered afternoon development.
A few organized multicells are possible atop a strongly heated
boundary layer, with pulse gusts and hail near severe limits
possible.

..Edwards/Bentley.. 08/27/2024

$$
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ACUS01 KWNS 281253
SWODY1
SPC AC 281252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Wed Aug 28 2024

Valid 281300Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF
NORTH AND SOUTH DAKOTA...

...SUMMARY...
Severe thunderstorms are expected from the Ohio Valley to the
northern Mid-Atlantic Coast, and across parts of North and South
Dakota.

...Synopsis...
In mid/upper levels, a progressive northern-stream pattern will
prevail through the period, with the main feature being a cyclone
now apparent in moisture-channel imagery near the southeastern
corner of BC. The associated 500-mb low should move eastward
roughly along, or just north of, the international border through
the period, with the accompanying trough extending south-
southwestward. By 00Z, the low should be near the southwestern
corner of SK, with trough to northern UT. By 12Z, the low should
reach extreme south-central SK, with trough across central MT to
southwestern WY.

Downstream, a complex but much lower-amplitude shortwave trough was
evident over Lake Superior and adjoining portions of ON and western
U.P. of MI. One part of this perturbation should break eastward to
the St. Lawrence Valley by the end of the period, while the trailing
part drifts eastward over Lake Superior and the U.P. Of perhaps
greater direct influence on convective potential, an MCV was
apparent in composited radar imagery over southeastern IA. The
associated perturbation should move across much of central IL today,
reaching western OH by 12Z tomorrow.

The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake
Michigan and WI, to northeastern NE, then a warm front over
southwestern SD, to a low over southeastern MT. This front is
expected to move southeastward by 00Z to coastal NS, Cape Cod, Long
Island, northern parts of MD/WV, and southern parts of OH/IN/IL,
becoming a diffuse warm front northwestward over central IA,
southwestern MN and central ND. There it will be overtaken by
another cold front -- initially analyzed through the low over
eastern MT and across northwestern WY. By 00Z, this second,
stronger cold front should extend from central ND across central/
southwestern SD to east-central WY. By 12Z, the western cold front
should extend from a low over southeastern ND or northeastern SD
across south-central SD, western NE and northeastern CO.

...Ohio Valley to Mid-Atlantic...
Widely scattered to scattered thunderstorms are expected along and
south of the front today from IN to the Mid-Atlantic Coast, and
perhaps the southern New England Coast/Long Island vicinity.
Damaging gusts and isolated large hail will be possible.

Coverage of convection is uncertain, but relative concentrations may
develop downshear from what is now disorganized/nonsevere convection
over OH (in the same UVV field), and ahead of the MCV over parts of
IL/IN, becoming organized across parts of IN/OH. Diurnal heating of
a favorably moist airmass is expected to weaken already modest
ambient MLCINH along the outlook corridor by late morning. With
lift along the front and prefrontal outflow/differential-heating
boundaries, growth of morning to early afternoon development into
one or more complexes appears to be a plausible scenario, rendering
a greater wind than hail threat. Surface dewpoints commonly in the
mid 60s to low 70s F will offset modest mid/upper-level lapse rates
enough to contribute to peak/preconvective MLCAPE in the 800-1500
J/kg range from OH eastward, and 1000-2000 J/kg back into portions
of IN. Weak, generally veered low/middle-level flow will limit
vertical shear. Still, nearly unidirectional westerly flow through
a deep layer will foster movement of convection parallel to the
low-level moisture-instability axis.

...Dakotas...
A line or arc of scattered thunderstorms should develop along/near
the cold front during late afternoon into evening, perhaps initially
over ND where deep-layer forcing will be stronger, then southward
into greater capping in SD, as the front impinges on greater
moisture and lingering boundary-layer instability.

Ahead of the cold front, enough easterly component to near-surface
flow will develop to support moist advection into the convective
genesis zone, with surface dewpoints into the 60s F becoming common.
Capping at the base of a modest EML will suppress development for
much of the afternoon, especially over SD, but once frontal lift
overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be
available southwest of (and parallel to) the warm front. Though the
strongest flow aloft and large-scale ascent will remain behind the
cold front, the eastern rim of stronger height falls will spread
over the frontal zone, with enough mass response to both foster
favorable vertical shear for supercells and enhanced storm-relative
flow in low levels. Effective-shear magnitudes of 30-40 kt (locally
higher) and broad low-level hodographs along and south of the warm
front should foster supercell development, until mergers and upscale
growth occur. Large to very large hail and severe gusts will be the
main concerns, though a tornado is possible. However, relatively
weak midlevel flow may encourage a transition to messier, quasi-
linear mode with embedded LEWP/bow formations for a few hours.
Activity should weaken overnight as it moves into stabilizing
boundary-layer air, though a 45-55-kt LLJ may encourage persistence
of a cluster or two tonight into the eastern Dakotas.

..Edwards/Bentley.. 08/28/2024

$$
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ACUS01 KWNS 291251
SWODY1
SPC AC 291249

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Thu Aug 29 2024

Valid 291300Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE UPPER MISSISSIPPI VALLEY REGION...

...SUMMARY...
Severe thunderstorms are most probable this afternoon and evening
over portions of the upper Mississippi Valley region, with a threat
for tornadoes, damaging to severe gusts, and sporadic large hail.

...Synopsis...
The mid/upper-level pattern will be characterized by a progressive
belt of westerlies across the northern tier of states, and messy
area of ridging across the south-central/southeastern CONUS,
suffused with numerous small vorticity maxima and a few slow-moving
MCVs. In that northern stream, a strong shortwave trough -- with
embedded closed cyclone now located over extreme southern SK -- will
move eastward to southern MB and the Dakotas by 00Z. The trough
should deamplify overnight and eject northeastward to
northwesternmost ON by 12Z, while a positively tilted trailing
portion of the trough lingers across parts of WI/IA/NE/KS. Farther
east, a weak perturbation -- evident in moisture-channel imagery
from just north of Lake Huron in ON to astern Lake Superior -- will
weaken gradually and move southeastward across the remainder of ON
to NY and New England by the end of the period. An even weaker
shortwave trough -- initially extending from central OH across
southern IN -- should move slowly southeastward into the central
Appalachians.

At the surface, 11Z analysis showed a triple-point low over
northeastern SD, with a warm front southeastward over southwestern
MN and northern IA, becoming quasistationary to a weak cold front
over central IL, southern IN, central OH, central PA , and NJ. The
eastern part of the front should drift southward over the Mid-
Atlantic through the period, while the western part proceeds
northeastward across MN/WI as a warm front. A cold front was drawn
from the low southwestward over west-central NE and east-central CO.
By 00Z, the cold front should reach northern/central MN,
northwestern IA, eastern NE, north-central/southwestern KS, and
parts of southeastern CO/northeastern NM. By 12Z, the front should
extend across parts of Lake Superior, WI, northern/western MO,
southeastern KS, northern/western OK, northwest TX, and southeastern
NM.

...Upper Mississippi Valley to central Plains...
Scattered thunderstorms should develop along/ahead of the surface
cold front -- earliest (around midday) where deep-layer lift is
strongest over northern/central MN, then later where stronger
capping, weaker upper support, but stronger heating will be present
from around the Missouri Valley southwestward. All severe hazards
will be possible with greatest vertical shear supporting a threat of
supercells in MN and perhaps northern IA for the first few hours of
the convective cycle. If supercells can remain discrete/mature long
enough before the quasi-linear evolution occurs, tornado potential
could be relatively maximized over central MN where the overlap of
large buoyancy, low LCL and greatest SRH is forecast. Activity
overall should evolve into a line of numerous thunderstorms by late
afternoon and evening, with severe gusts and marginal hail becoming
the dominant concerns. Convection should weaken over eastern and
southern parts of the "marginal area tonight, while moving into a less-unstable, larger-CINH airmass from WI to southern KS.

Although the main mid/upper cyclone/trough will be pivoting
northeastward over Canada, the southeastern rim of associated height
falls and mass response will pass across the "slight risk" outlook
area. This should back the near-surface flow ahead of the front
enough to enlarge low-level hodographs and shear vectors, and to
strengthen effective-shear magnitudes into the 30-40-kt range
(decreasing southward over IA). A deep troposphere, rich boundary-
layer moisture with dewpoints commonly in the upper 60s to low 70s
F, and steep low-level lapse rates, should support MLCAPE commonly
in the 2500-3500 J/kg range, and locally nearing 5000 J/kg, within
the northward-narrowing warm sector, over IA/MN part of the outlook.
Farther southwest, buoyancy will weaken due to somewhat less
moisture content and greater boundary-layer mixing.

...VA/NC to southern PA...
Scattered multicell thunderstorms are expected to form this
afternoon along and south of the front over the outlook area,
offering isolated gusts near severe limits and marginally severe
hail. This activity will develop in a plume of rich low-level
moisture, with lower-elevation surface dewpoints in the upper 60s to
low 70s F. That, along with diurnal heating offsetting modest
midlevel lapse rates, should support MLCAPE in the 2000-3000 J/kg
range. Weak deep-layer flow/shear should keep activity relatively disorganized, with pulse severe possible.

..Edwards/Bentley.. 08/29/2024

$$
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ACUS01 KWNS 301234
SWODY1
SPC AC 301232

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0732 AM CDT Fri Aug 30 2024

Valid 301300Z - 311200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN LOWER MICHIGAN...

...SUMMARY...
Scattered strong to severe thunderstorms are possible across eastern
Lower Michigan this afternoon, with damaging winds the main threat.
Isolated strong to severe thunderstorms may occur into parts of the
Midwest, and also across portions of the Carolinas and Virginia into
northeast Georgia.

...Great Lakes to the Mid Mississippi Valley...
Weak/elevated thunderstorms ongoing this morning from parts of
northern IL into Lower MI should continue to gradually weaken. In
their wake, moderate instability should develop along and ahead of a
cold front that will extend from the Upper Great Lakes region
southwestward to the southern Plains by this afternoon. This front
should make continued slow east-southeastward progress across these
regions through the period as an upper trough moves eastward over
Ontario, the Great Lakes, and Midwest. Stronger mid-level winds
associated with this feature will generally remain confined to
Canada. But, modest enhancement to the west-southwesterly
low/mid-level flow should be present over parts of Lower MI this
afternoon.

Even though low-level convergence along the front should remain
fairly weak, expectations are for at least scattered thunderstorms
to develop along much of its length from eastern Lower MI to the mid
MS Valley and southern Plains. The combination of moderate
instability with modest deep-layer shear should promote some
convective organization, with loosely organized multicells/clusters
likely becoming the dominant thunderstorm mode. Steepened low-level
lapse rates with daytime hearing should encourage occasional strong
to damaging winds, with slightly stronger low/mid-level flow perhaps
supporting a relatively greater threat ahead of the front in eastern
Lower MI. Isolated hail may also occur with the strongest cores.
Convection should weaken with time this evening with the loss of
daytime heating.

...Southern Appalachians to the Southern Mid-Atlantic...
Upper ridging will persist over the Southeast today. Very weak
low/mid-level flow is expected to limit overall thunderstorm
organization. Still, moderate instability should be present this
afternoon as daytime heating occurs along and south of a stalled
front over southern VA and northern NC. Even though deep-layer shear
will remain negligible, pulse-type thunderstorms that develop in
this moderately unstable and high precipitable water environment
could produce isolated strong to damaging downburst winds this
afternoon.

..Gleason/Leitman.. 08/30/2024

$$
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ACUS01 KWNS 311241
SWODY1
SPC AC 311240

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 AM CDT Sat Aug 31 2024

Valid 311300Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY...

...SUMMARY...
Severe thunderstorms capable of producing mainly damaging winds will
be possible today from parts of the central Appalachians into the
Ohio and Tennessee Valleys. Isolated severe wind gusts may also
occur across parts of the northern Great Lakes.

...Mid-Atlantic into the Ohio and Tennessee Valleys...
A mid/upper-level trough will make slow eastward progress today
across Ontario/Quebec and the Great Lakes while amplifying further.
Ahead of this feature, a surface front should continue to lose
definition and weaken through the day as it moves eastward over
parts of the Northeast/Mid-Atlantic, and southeastward over the OH
Valley before eventually stalling. Recent visible satellite imagery
shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay
destabilization, especially east of the Blue Ridge Mountains. Still,
area 12Z soundings and recent surface observations indicate a moist
low-level airmass remains in place ahead of the weak cold front.
Generally less cloud cover with westward and southward extent into
the upper OH Valley and TN Valley should allow for greater
instability to develop this afternoon across these regions.

The stronger mid-level flow associated the upper trough is expected
to remain generally displaced to the north/west of the surface warm
sector. Even so, modestly increasing west-southwesterly winds with
height through mid levels should support around 20-30 kt of
deep-layer shear across parts of the central Appalachians and upper
OH Valley vicinity. This shear will be sufficient for loosely
organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered
damaging winds should be the main threat with this convection,
although some hail may also occur with the strongest cores. Activity
should weaken with eastward extent late this afternoon and evening
across the Mid-Atlantic as it encounters a less unstable airmass.
Weaker deep-layer shear with southward extent into the lower OH
Valley and TN Valley will likely limit overall thunderstorm
organization. But, occasional damaging winds may still occur with
thunderstorms along/south of the front as low-level lapse rates
steepen with diurnal heating.

...Northern Great Lakes...
Strong west-northwesterly mid-level flow will be present today over
the Upper Midwest and northern Great Lakes, in association with a
shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture
and related instability are both expected to remain limited,
large-scale ascent and strong deep-layer shear may support the
development low-topped convection this afternoon. If these
thunderstorms can form and be sustained, then isolated strong to
severe winds may occur given the forecast strength of the low to
mid-level flow amid steepened low-level lapse rates.

..Gleason/Leitman.. 08/31/2024

$$
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ACUS01 KWNS 011250
SWODY1
SPC AC 011248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sun Sep 01 2024

Valid 011300Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE SOUTHERN APPALACHIANS INTO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND...

...SUMMARY...
Strong thunderstorms capable of producing isolated damaging winds
may occur this afternoon across parts of the southern Appalachians
into the Mid-Atlantic and southern New England.

...Southern Appalachians into the Mid-Atlantic and Southern New
England...
Thunderstorms should gradually increase in coverage this afternoon
along/south of a weak front that extends from the Mid-South/lower OH
Valley into the Mid-Atlantic. Morning visible satellite imagery
shows plentiful cloud cover near this boundary, and downstream
across parts of NC and the Mid-Atlantic into southern New England.
Still, filtered daytime heating of a moist low-level airmass should
allow at least weak instability to develop by early to mid afternoon
along and south/east of the front, even though mid-level lapse rates
will remain poor.

The glancing influence/ascent of an upper trough over eastern
Canada, along with weak orographic lift, will likely encourage
convection development through the afternoon and early evening.
Mid-level flow and related deep-layer shear are forecast to remain
fairly modest, especially with southward extent across the
Mid-Atlantic into the Carolinas and southern Appalachians. Still,
enough flow and related shear may be present to support modest
thunderstorm organization. Multiple loosely organized multicell
clusters may eventually develop and consolidate by late afternoon
and early evening, while posing some threat for isolated strong to
damaging winds as they move generally eastward. The greatest
concentration of thunderstorms should exist across parts of southern
VA into NC and upstate SC where greater instability is forecast this
afternoon. But, confidence in a more organized wind threat remains
too low to include greater severe wind probabilities.

...Western/Northern New York into Northern New England...
As the primary upper trough and related surface cold front continue
eastward across Ontario/Quebec today, daytime heating of a modestly
moist low-level airmass will occur over parts of western/northern
NY. Although poor mid-level lapse rates will likely hinder the
development of any more than weak instability across this area
(MLCAPE generally 500 J/kg of less), low/mid-level winds and related
shear in the cloud-bearing layer is expected to strengthen through
this afternoon with the approach of the upper trough. Some high-resolution/convection-allowing model guidance shows a
low-topped line of thunderstorms developing this afternoon along or
just ahead of the cold front. As low-level lapse rates steepen with
daytime heating, some of this convection could produce isolated
strong to severe wind gusts given the strengthening low/mid-level
flow expected. The area impacted should remain fairly small across western/northern NY (generally downstream of Lake Ontario) due to
more even more limited instability farther east across central NY
into northern New England.

..Gleason/Leitman.. 09/01/2024

$$
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ACUS01 KWNS 021240
SWODY1
SPC AC 021238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Mon Sep 02 2024

Valid 021300Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE INTERIOR PACIFIC NORTHWEST INTO THE NORTHERN GREAT BASIN/ROCKIES...

...SUMMARY...
Isolated to scattered thunderstorms across the northern Great Basin
and parts of the interior Pacific Northwest may be capable of
occasional strong to severe wind gusts this afternoon and evening.

...Interior Pacific Northwest into the Northern Great
Basin/Rockies...
A closed upper low approaching the northern CA and OR Coast will
continue eastward today across the Pacific Northwest and northern
Great Basin. Associated 35-50 kt mid-level south-southwesterlies
will overspread these regions through the afternoon and evening.
Large-scale ascent attendant to the upper low has already encouraged
weak, elevated convection this morning across pats of eastern OR and
vicinity. Current expectations are for additional showers and
thunderstorms to develop later this afternoon as daytime heating
occurs, mainly across parts of central/eastern OR into ID and
northern NV/northwest UT. This convection will likely be rather
high-based (LCLs around 3-4 km AGL), as latest surface observations
and area 12Z soundings show very limited low-level moisture, and
total PWAT values generally 0.5-0.7 inches. Even with rather weak
buoyancy forecast across much of this area, a deeply mixed boundary
layer should encourage efficient evaporative cooling of convective
downdrafts. An isolated risk for strong/gusty winds approaching and occasionally exceeding severe levels remains apparent with this
high-based convection as it spreads generally north-northeastward
through the afternoon/evening before eventually weakening.

..Gleason/Leitman.. 09/02/2024

$$
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ACUS01 KWNS 031235
SWODY1
SPC AC 031234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Tue Sep 03 2024

Valid 031300Z - 041200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN ROCKIES/GREAT BASIN AND ADJACENT HIGH PLAINS...

...SUMMARY...
Thunderstorms developing across the northern Rockies and adjacent
portions of the Great Basin this afternoon may produce occasional
strong to severe wind gusts, before spreading eastward toward the
northern High Plains this evening.

...Northern Great Basin/Rockies into the Adjacent High Plains...
An upper trough/low over the Pacific Northwest this morning will
continue moving eastward today across the northern Rockies. This
feature is forecast to gradually weaken through the period, but
enhanced mid-level west-southwesterly flow will persist across parts
of the northern Great Basin into the northern Rockies and adjacent
High Plains. As large-scale ascent associated with the upper trough
overspreads the northern Rockies, thunderstorms should develop over
the higher terrain through early afternoon in tandem with daytime
heating.

Latest surface observations show somewhat greater low-level moisture
across this region, with surface dewpoints generally in the mid 40s
to low 50s across central ID into southwest MT. Although instability
is forecast to remain fairly modest this afternoon, deep-layer shear
around 25-35 kt should be sufficient to support organized
convection, including the potential for a couple of marginal
supercells initially with associated hail/wind threat. With
steepened low/mid-level lapse rates present, this activity should
continue to pose some threat for isolated strong to severe wind
gusts as it congeals and spreads east-northeastward across parts of
the northern High Plains through this evening.

Somewhat more limited low-level moisture should be present this
afternoon farther south into WY and northern UT. Even so, diurnal
heating will aid in a deeply mixed boundary layer by this afternoon,
and steep mid-level lapse rates are also expected to remain over
this region. The net result will be high-based thunderstorms capable
of producing isolated strong to severe winds initially developing
across northern UT into far eastern ID, and subsequently moving east-northeastward over WY through the evening. Confidence in a more concentrated corridor of severe winds remains generally low at this
time given the weak instability and modest deep-layer shear
forecast, especially with southward extent into the northern Great
Basin and WY.

..Gleason/Leitman.. 09/03/2024

$$
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ACUS01 KWNS 041218
SWODY1
SPC AC 041216

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0716 AM CDT Wed Sep 04 2024

Valid 041300Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL ROCKIES INTO THE NORTHERN/CENTRAL PLAINS AND UPPER
MISSISSIPPI VALLEY...

...SUMMARY...
Isolated strong to severe thunderstorms capable of gusty winds and
hail may occur this afternoon and evening across parts of the
central Rockies into the northern/central Plains and upper
Mississippi Valley.

...Central Rockies into the Northern/Central Plains and Upper
Mississippi Valley...
A weak shortwave trough over the northern Rockies and adjacent Great
Basin this morning will become absorbed later today into an
amplifying upper trough over the Canadian Prairie provinces and
northern Plains. At the surface, a cold front related to the upper
trough will continue southward over the northern Plains, and
southeastward across the Upper MS Valley through the period. Modest
low-level moisture is forecast to be in place ahead of this boundary
across the northern Plains and upper MS Valley, with more limited
moisture expected farther west across the central Rockies and
adjacent High Plains. Relatively cool mid-level temperatures
associated with the weak shortwave trough and the presence of steep
mid-level lapse rates should aid in the development of weak
instability across parts of WY, northern CO, and vicinity this
afternoon. Sufficient deep-layer shear (generally 25-35 kt) should
support some updraft organization with convection that initially
forms over the higher terrain before subsequently spreading
eastward. Isolated instances of marginally severe hail and
strong/gusty winds may occur with the more cellular development.
But, some increase in strong to severe wind potential may be
realized as thunderstorms move into an area of steeper low-level
lapse rates across the central High Plains by late this afternoon
and early evening, especially if any small clusters can form.

The severe potential along much of the length of the front in the
northern Plains and upper MS Valley appears rather conditional.
While large-scale ascent associated with the approaching upper
trough should gradually overspread the warm sector by late
afternoon/early evening, most guidance continues to suggest that a
cap and substantial MLCIN will hinder robust convection from
developing through much of the day. Even so, sufficient instability
and shear should be in place along/ahead of the front to support an
isolated hail/wind threat if thunderstorms can form and be sustained
through the evening and early overnight period. The post-frontal
regime across much of MT into ND and western SD appears unlikely to
support severe convection. Accordingly, the Marginal Risk has been
trimmed southward to account for recent guidance and observational
trends.

..Gleason/Leitman.. 09/04/2024

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ACUS01 KWNS 051243
SWODY1
SPC AC 051242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Thu Sep 05 2024

Valid 051300Z - 061200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
FAR SOUTH-CENTRAL COLORADO INTO NORTHERN/CENTRAL NEW MEXICO...

...SUMMARY...
Thunderstorms capable of producing isolated severe wind gusts and
hail will be possible today across parts of far south-central
Colorado into northern/central New Mexico.

...Central/Southern Rockies into the Southern High Plains...
On the southwest fringe of large-scale upper troughing over Canada
and the northern Plains/Upper Midwest, a mid-level shortwave trough
over the central Rockies this morning will move generally southward
across NM and vicinity through the day. Even though low-level
moisture remains fairly modest across the southern Rockies and
adjacent High Plains along/near of a cold front, cool mid-level
temperatures and somewhat steepened lapse rates aloft will likely
contribute to the development of around 500-750 J/kg of MLCAPE by
early afternoon as daytime heating occurs. Initial development of
robust convection by around 18-19Z will likely be tied to the higher
terrain as weak large-scale ascent associated with the shortwave
trough overspreads the south-central Rockies in a low-level
post-frontal regime. This activity should then spread generally south-southeastward across parts of northern/central NM through the
late afternoon and into the evening. While low-level easterly flow
ahead of the front is forecast to remain weak, veering winds with
height through mid/upper levels should still support around 25-35 kt
of effective bulk shear and some updraft organization. The strongest
cores that can develop may be capable of producing severe hail.
Otherwise, the threat for isolated strong to severe wind gusts
should spread southward in tandem with any small clusters that can
form.

...Great Lakes/Midwest to the Central Plains...
Generally elevated convection is ongoing this morning across parts
of the Upper Midwest along and near a surface cold front, and ahead
of a large-scale upper trough moving generally southeastward.
Instability across this region is expected to remain weak (MUCAPE
500 J/kg or less), which should tend to limit the overall severe
threat. Still, some of the stronger cores could produce small hail
or gusty winds in the short term. Other thunderstorms may eventually
develop this afternoon along/near the front across parts of the
Midwest and/or central Plains. Regardless, the overall severe threat
across these regions currently appears too limited to introduce low
severe probabilities.

..Gleason/Leitman.. 09/05/2024

$$
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ACUS01 KWNS 061247
SWODY1
SPC AC 061246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Fri Sep 06 2024

Valid 061300Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
OHIO TO THE OHIO VALLEY...

...SUMMARY...
Strong to locally severe storms are possible this afternoon from
Lake Erie across much of Ohio to the Ohio Valley.

...Synopsis...
A highly amplified mid/upper-level pattern will persist across the
CONUS, but with some weakening of the western mean ridge and
intensification of troughing over the Great Lakes/Ohio Valley
regions. The latter will occur in relation to a synoptic-scale
trough with several accompanying vorticity maxima and broad cyclonic
flow -- apparent in moisture-channel imagery over much of northern
ON and the Lake Superior vicinity. Phasing of accompanying
shortwaves/ vorticity lobes will contribute to both amplification
and wavelength shortening through the period. A closed 500-mb low
should develop around 00Z near the eastern end of Upper MI, with
trough near an MKG-ORD-MVN line. By 12Z, a fully developed cyclone
should cover much of ON from the southern end of James Bay to Lake
Erie, with 500-mb trough extending southwestward near a CVG-BNA
line. Associated cyclonic flow at that time will cover most of the
CONUS over and east of the mid/upper Mississippi Valley.

At the surface, a cold front related to the ON trough was drawn at
11Z near a DTW-FDY-IND-ICT line. This front should proceed eastward/southeastward across the Ohio Valley, Lower Great Lakes and
into the central/northern Appalachians through the period, ahead of
the mid/upper trough. By 00Z, the front should extend from Lake
Ontario across western parts of NY/PA to southeastern OH, northern
middle to western TN, and AR, becoming diffuse amidst northeast flow
on both sides over OK. Northeasterlies over the southern Plains
south of the cold front will be largely in isallobaric response to a
deepening surface frontal-wave low over the northwestern Gulf,
initially drawn about 100 nm south of GLS, and forecast to drift
erratically eastward through tonight. Strong/organized convection
related to the Gulf cyclone is expected to remain over water through
the period.

...OH, Ohio Valley...
Damaging to isolated, marginally severe gusts, as well as marginal
hail, will be possible with thunderstorms moving eastward across the
outlook area today.

A broken line of convection -- including widely scattered non-severe thunderstorms -- is apparent this morning from northwestern OH to
western MO approximately along the low-level cold front. This
activity, or succeeding/newer development after a short time gap
later this morning -- should become better organized between Lake
Erie and the Ohio Valley around midday as the foregoing boundary
layer (and prospective inflow) destabilizes. This will occur in
response to a combination of warm advection and diurnal heating/
mixing, whose mixing-related moisture-reduction effects will be
counterbalanced to some extent by moist advection. Activity should
move into a narrow corridor of 50s to mid 60s F surface dewpoints,
combining with diurnal heating to support patchy, highly variable
MLCAPE in the 500-1500 J/kg range.

Substantial westerly component to prefrontal near-surface flow will
limit both convergence and vertical shear, though weak MLCINH will
permit frontal development/maintenance of thunderstorms, regardless.
Around 30-35 kt effective-shear magnitudes will support mainly
multicells, though some intermittent/transient supercell character
will be possible for longer-lived, discrete cells. Activity should
weaken this evening as it moves eastward out of the most favorable
moisture, and into a nocturnally cooling/stabilizing boundary layer.

..Edwards/Kerr.. 09/06/2024

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ACUS01 KWNS 081225
SWODY1
SPC AC 081224

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0724 AM CDT Sun Sep 08 2024

Valid 081300Z - 091200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Though a few strong thunderstorm gusts may be noted in the interior
Northwest and central High Plains, severe potential appears too low
and disorganized for an outlook area.

...Synopsis/Discussion...
In mid/upper levels, the large-scale pattern will deamplify somewhat
over the CONUS this period, but maintain a mean trough in the Great
Lakes and eastern CONUS, and mean ridging over the Intermountain
West and Southwestern deserts. A shortwave trough -- evident in moisture-channel imagery over the interior of OR/WA into far
northern CA -- is forecast to continue weakening as it moves
northeastward, crossing the northern Rockies between 06-12Z. Still,
associated cooling aloft and midlevel moisture, over pockets of
marginally favorable low-level moisture and diurnal surface heating,
will contribute to general thunderstorm potential in parts of the
interior Northwest and Intermountain West. A few of these high-
based cells may produce strong gusts, but severe potential appears
to be limited by lack of greater moisture/buoyancy.

Farther east over the central Rockies and adjoining High Plains,
isolated to widely scattered thunderstorms are possible this
afternoon into evening. Activity should be related to diabatic
heating of elevated terrain, along with lift near a surface lee
trough, and a corridor of meager but sufficient low-level moisture.
Beneath strongly difluent but weak west to northwest flow in mid/
upper levels, bulk shear should be modest, despite considerable
veering with height. Here too, a few cells may produce strong gusts
through a well-mixed subcloud layer, and a severe gust cannot be
ruled out. However, severe potential appears too isolated, poorly
focused and conditional for a categorical risk area. Elsewhere,
isolated to scattered thunderstorms will be possible in a very moist
air mass (but with poor lapse rates) from parts of the Gulf Coast
States across FL and the southern Atlantic Coast.

..Edwards/Kerr.. 09/08/2024

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ACUS01 KWNS 091240
SWODY1
SPC AC 091239

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 AM CDT Mon Sep 09 2024

Valid 091300Z - 101200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF NEW YORK...

...SUMMARY...
Isolated damaging thunderstorm gusts are possible in parts of New York.

...Synopsis...
Mid/upper-level flow will become more zonal across most of the
northwestern and north-central CONUS, as a series of embedded
shortwave troughs penetrates/flattens antecedent ridging over the
Intermountain West and central/northern Rockies. Downstream, a
substantial cyclone -- initially centered near the southwestern edge
of Labrador -- anchors mean troughing that extends southwestward
down the Appalachians. The cyclone will eject northeastward over
Labrador through the period. In its southwestern quadrant, a
shortwave trough was apparent in moisture-channel imagery over
northeastern ON, approaching Georgian Bay and the neck of ON. This
feature should move southeastward to the upper St. Lawrence Valley,
eastern Lake Ontario and western NY by 00Z, then across southern New
England and offshore from the northern Mid-Atlantic Coast overnight.

The 11Z surface analysis showed a weak cold front from southern QC,
through a frontal-wave low over northern Lake Huron, then across
northern parts of WI/MN. The low should move east-southeastward
toward Lake Ontario and weaken through the day, while the cold front
and associated veering wind shift cross the remainder of ON and
start moving into NY. The front should cross the remainder of NY
and most of New England and PA overnight. An older, quasistationary
front was drawn across north-central FL westward over north-central
Gulf shelf waters, then bending southwestward into the western parts
of the developing tropical cyclone in the western Gulf.

Potential TC 6 -- now offshore from the Mexican Gulf Coast -- is
forecast by NHC to organize into a tropical storm this period.
Given the forecast track, intensity and wind radii, any developing
favorable sector for supercells/tornadoes will remain well out in
the Gulf day-1, and not an overland tornado concern until day 3,
when a risk area has been introduced northeast/east of the forecast
center track. See NHC advisories on this system for latest tropical watches/warnings, and path/strength forecasts.

...NY...
Widely scattered to scattered thunderstorms are expected to move
southeastward to eastward across the outlook area from early
afternoon into early evening. Isolated damaging gusts, and perhaps
a gust or two near severe limits, may occur from the most vigorous
embedded cells.

This convection will be related to a compact (mesoscale) but strong
field of large-scale ascent preceding the shortwave trough, related
to its progressive field of DCVA, and forcing in the left-exit
region of a cyclonically curved speed max in the 250-500-mb layer.
The UVV field likely is manifest already by convection now over
Georgian Bay and vicinity, moving toward what should become a more
unstable environment over the outlook area. Deep-layer mean lapse
rates likely will never get steeper than about 6.5 C/km in this
setting. Still, the combination of subtle cooling aloft, weak but
sufficient boundary-layer moisture, and some diurnal heating ahead
of the UVV field, should deepen the buoyant layer enough to yield
pockets of 500-700 J/kg MLCAPE. Weak low-level shear, and 25-30 kt effective-shear magnitudes in forecast soundings, indicate activity
should be multicellular. A shallow but well-mixed subcloud layer --
containing around 7 C/km lapse rates -- will support strong
downdraft accelerations in some of the cores.

..Edwards/Kerr.. 09/09/2024

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ACUS01 KWNS 101244
SWODY1
SPC AC 101243

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 AM CDT Tue Sep 10 2024

Valid 101300Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER COASTAL
AREAS OF LOUISIANA...

...SUMMARY...
Marginal tornado potential may reach coastal areas of Louisiana
during the late overnight/early morning hours.

...Synopsis...
In mid/upper levels, a strong shortwave trough now over the eastern
Gulf of Alaska is forecast to dig southeastward and develop a closed
500-mb cyclone tonight, with the low about 150 nm west of AST by 12Z
tomorrow. Ahead of this progressive and intensifying perturbation,
height falls and strengthening cyclonic flow will spread across the northwestern CONUS throughout the period, combining with modest low/ middle-level moisture to support thunderstorm potential in parts of
the Northwest, in addition to the diurnal-cycle convection across
the Four Corners region, central/northern Rockies and parts of MT.

Downstream, mid/upper flow should be nearly zonal from the Rockies
across the Great Lakes. An embedded shortwave trough was evident in moisture-channel imagery over the Dakotas. This feature is forecast
to move eastward to MN by 00Z, then across the Upper Great Lakes to
Lake Huron and adjoining parts of ON by 12Z. Farther south, a weak,
cut-off, mid/upper-level low over north-central TX should drift
erratically near its present location, while increasingly
influencing the path of Tropical Storm Francine.

The 11Z surface analysis showed a wavy, quasistationary frontal zone
fro Atlantic waters offshore SC, across northern FL to near the
Mississippi River mouth, then a warm front arching across Gulf
waters just south of the LA and TX Coasts, and into western parts of
the Francine circulation. This boundary should move little from
about 90W eastward, but remain a warm front over the upper TX and LA
coastal waters, diffusely shifting inland over southern LA through
the period.

...LA Coast...
T.S. Francine -- initially centered southeast of BRO -- is forecast
by NHC to turn northeastward across the northwestern Gulf today and
become a hurricane, then move ashore in Louisiana on day 2.
Suitably rich low-level moisture already is in place over coastal
LA, and scattered to numerous showers and thunderstorms should cover
the outlook area throughout much of the period, even well northeast
of Francine's center. However, supercell potential will await
sufficiently strong wind fields reaching the coastline ahead of the
cyclone to enlarge hodographs favorably -- likely during the last
few hours of the period. Then, tornado potential will be a matter
of having relatively distinct/discrete, outer-band convection that
can survive long enough to mature into supercells before weakening
again in more-stable inflow air -- either inland or in broader
precip areas. Unconditional probabilities are kept at marginal
levels for now, given the late timing of the favorable kinematic
fields, the nocturnal min in overland instability, and convective/
structural uncertainties with Francine.

..Edwards/Kerr.. 09/10/2024

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ACUS01 KWNS 101942
SWODY1
SPC AC 101940

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 PM CDT Tue Sep 10 2024

Valid 102000Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF COASTAL/SOUTHEAST LOUISIANA...

...SUMMARY...
Marginal tornado potential may reach coastal areas of Louisiana
during the late overnight/early morning hours.

...20z Update...
The forecast remains on track and no changes are needed to the D1
Convective Outlook. See previous discussion below for more
information.

..Thornton/Gleason.. 09/10/2024

.PREV DISCUSSION... /ISSUED 1122 AM CDT Tue Sep 10 2024/

...Southern Louisiana Late Tonight/Early Wednesday Morning...
The latest NHC forecast indicates Tropical Cyclone Francine will
move northeastward over the western Gulf of Mexico tonight through
early Wednesday morning. Morning surface observations show a stalled
front remains situated over the northern Gulf, with greater
low-level moisture (mid/upper 70s surface dewpoints) generally
confined near or just off the LA/MS/AL Gulf Coast. As Francine
approaches the LA Coast late tonight, this very moist low-level
airmass over the northern Gulf should gradually spread inland along
parts of the immediate central Gulf Coast, supporting weak
boundary-layer instability. As Francine approaches, a corresponding
increase in low-level flow and related effective SRH should support
some threat for tornadoes with any low-topped supercells in outer
rain bands to the east-northeast of the central circulation. Latest
guidance continues to suggest that the better tornado potential over
land will occur in the Day 2/Wednesday time frame (after 12Z). But,
an isolated/marginal tornado threat still remains apparent along
parts of the LA Coast for the last few hours of the Day 1 period
(08-12Z) early Wednesday morning, where a Marginal Risk has been
maintained.

$$
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ACUS01 KWNS 111629
SWODY1
SPC AC 111627

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 AM CDT Wed Sep 11 2024

Valid 111630Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GULF COAST...

...SUMMARY...
Hurricane Francine will pose a tornado threat through tonight across
the middle Gulf Coast region.

...Gulf Coast - Hurricane Francine...
Hurricane Francine will continue to generally move northeastward
toward the southern Louisiana coast. Reference NHC for the latest
forecast track and intensity details. As Francine approaches the
coast later this afternoon into evening, a considerable
strengthening of east-southeasterly winds on its east-northeast
periphery will lead to an increasing near-shore/inland supercell
risk. This will be in tandem with a northward shift of a maritime
warm front and associated moisture-rich air, which will tend to stay
with about 50-75 miles within the Gulf Coast spanning southeast
Louisiana to the Florida Panhandle. The supercell/tornado risk is
expected to steadily increase this afternoon across southeast
Louisiana, transitioning northeastward toward southeast Mississippi,
southern Alabama and the Florida Panhandle into this evening and
overnight, with a few tornadoes possible regionally.

...Northern Rockies and northern High Plains...
High-based thunderstorms are expected to pose an isolated severe
risk late this afternoon into evening, with severe-caliber wind
gusts a possibility, along with some hail possible as well across
the northern Rockies including parts of Idaho and western Montana.
This is influenced by the lead portion of a Pacific Northwest
upper-level trough, with preceding height falls and the exit region
of the upper jet overspreading the northern Rockies and northern
High Plains through tonight.

Thunderstorms should increase in coverage/intensity by late
afternoon, especially from far southeast Oregon into southern Idaho,
southern Montana and northwest Wyoming. Around 250-750 J/kg MLCAPE
coincident with 25-35 kt of effective shear will support clusters
and bands of storms capable of hail and stronger wind gusts.

Additional widely scattered storms are expected across the northern
High Plains within a modestly moist environment. Dry sub-cloud
layers will support the potential for stronger downdrafts and the
possibility of some severe-caliber wind gusts.

..Guyer/Jirak.. 09/11/2024

$$
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ACUS01 KWNS 120042
SWODY1
SPC AC 120040

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 PM CDT Wed Sep 11 2024

Valid 120100Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL GULF COAST IN ASSOCIATION WITH HURRICANE FRANCINE....

...SUMMARY...
Tornado threat continues with Hurricane Francine across the middle
Gulf Coast region.

...01z Update...

Center of Hurricane Francine has moved onshore and will continue
lifting slowly north through sunrise. Stronger, deeper updrafts are
currently located within the eastern hemisphere of the low, per
lightning data, along with a few longer-lived supercells. Have
adjusted severe probabilities down along the western portion of
Francine to reflect the latest position. Tornado threat continues
with stronger supercells.

High-level diffluent flow is noted across the northern Rockies this
evening ahead of a pronounced short-wave trough that currently
extends across eastern WA/OR into NV. 500mb speed max will dig into
the base of the trough later tonight across the Great Basin which
will ensure the left-exit region of the jet will spread across
eastern ID/southern MT/western WY. Considerable amount of lightning
is currently noted with convection ahead of the short wave, and some
stronger wind gusts have also been observed. 00z sounding from Great
Falls, MT exhibited meager buoyancy, but steep lapse rates are
contributing to MLCAPE on the order of 500 J/kg across southern MT
into eastern ID/western WY. This continues to favor some risk for
locally severe winds with the more robust convection this evening.

..Darrow.. 09/12/2024

$$
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ACUS01 KWNS 121249
SWODY1
SPC AC 121248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Thu Sep 12 2024

Valid 121300Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE NORTHERN GREAT PLAINS...AND FROM THE FLORIDA PANHANDLE TO
NORTH-CENTRAL ALABAMA...

...SUMMARY...
A few tornadoes are possible today, mainly in the morning and
afternoon from the Florida Panhandle to north-central Alabama.
Scattered large hail and severe gusts (some significant) are
expected across the eastern Montana vicinity during the afternoon to
early evening.

...Synopsis...
Over the CONUS, in mid/upper levels, a highly amplified initial
pattern will become more blocky through the period. A strong
northern-stream trough with an intermittently closed cyclone is
apparent in moisture-channel imagery from the Canadian Rockies
southward over ID to the central Great Basin. The 500-mb low is
forecast to move northeastward across western and northern MT to
near the southwestern corner of SK by the end of the period. By
then, the attached trough will deamplify slightly and become more
positively tilted, extending from the low to central UT. A
baroclinic leaf with strongly difluent flow aloft precedes the
trough in satellite imagery over southeastern ID, western WY and
central MT, with an eastward shift and some reinforcement expected
today as small vorticity maxima pivot northeastward out of the
trough.

Meanwhile, an initially separate, weak 500-mb low now over the Red
River near PRX, and the remnants of Tropical Storm Francine aloft,
are progged to merge over the upper Delta/Mid-South region today
into tonight. The result after 06Z should be a slow-moving
mid/upper-level low over AR, nearly stacked above the weakening
low-level vortex just to the east around MEM. [See NHC advisories
for latest forecast track/intensity guidance on Francine.] An
anticyclone aloft should form later today and expand tonight
northeast of that low, over the Upper Great Lakes region.

At the surface, 11Z analysis showed a warm front across northernmost
FL to the coastal FL Panhandle, then slightly inland over the
western Panhandle, southwestern AL and southeastern MS. This
boundary will move slowly northward/inland today, demarcating the
north rim of mid-70s F surface dewpoints. Meanwhile, a surface low
was drawn over eastern MT west of GDV, with slow-moving cold front south-southwestward across northeastern/central WY. The low and
front will continue slow/intermittent eastward progress today, then
move into the western Dakotas around 22-00Z, then eastward to the
central Dakotas late overnight.

...Northern Great Plains...
Strong-severe thunderstorms are possible this afternoon into
evening, along and behind the front, with the most probable severe
potential arising from activity moving north-northeastward from
northern WY. High-based supercells and multicells are possible,
offering large hail and severe gusts. Some of the activity may
aggregate upscale into one or two bowing clusters, racing northward
accompanied by a swath of better-organized, potentially significant
(65+ kt) gust potential.

Thunderstorms may develop along the front in early-mid afternoon, as
well as in and near the Bighorns, where diurnal heating of elevated
terrain preferentially removes MLCINH earliest. A corridor of
favorable surface moisture will remain near and behind the front and
ahead of this convection. Meanwhile, midlevel temperatures will
cool and steepen low/middle-level lapse rates, as large-scale ascent
spreads over the area, both ahead of the ejecting mid/upper trough
and in the left-exit region of a cyclonically curved 300-mb jet
segment. This will occur atop a deep and well-mixed boundary layer
containing nearly dry-adiabatic lapse rates. A northerly flow
component west of the front will enhance storm-relative winds in the
inflow layer, as well as low-level and deep-layer shear,
strengthening lift and helping to maintain and further organize the
convection. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear
magnitudes will support the severe potential.

Convection forming later and farther east near the front over the
western Dakotas, from late afternoon into evening, also may pose a
strong to locally severe gust threat for a few hours, and the
marginal outlook area has been expanded eastward somewhat to give
more room for that process. Flow aloft will bear a substantial
component parallel to the convective axis, indicating a largely
training or linear configuration is possible, along the western rim
of a 50-60-kt LLJ fostering warm advection and moisture transport
above the surface. However, the near-surface airmass over the
central Dakotas should stabilize with time and eastward extent
tonight, limiting duration and eastward shift of the threat.

...Southeastern CONUS...
Tropical Storm Francine is forecast to continue moving northward
over MS, and to lose definition as it interacts more closely with
the mid/upper-level low. Accordingly, associated deep-layer winds
will continue to weaken, but low-level shear will remain favorable
through most of the day well east-southeast to southeast of center.
A destabilizing airmass along and south of the warm/marine front
will support a continued, slow inland shift of supercell potential
amid enlarged hodographs. The favorable environment will be bounded
on the west by a dry slot and veering low-level flow, on the
northeast by unsuitably stable air in heavy precip and north of the
front, and on the south by a gradual weakening of low-level winds
and shear as the cyclone center pulls away and fills. In the
favorable corridor, where inflow parcels are surface-based, expect
effective SRH in the 200-500 J/kg range, very rich moisture, low
LCL, and weak MLCINH. The threat should diminish overnight as the
airmass slowly stabilizes inland, and the system continues to weaken
overall.

..Edwards/Kerr.. 09/12/2024

$$
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ACUS01 KWNS 131245
SWODY1
SPC AC 131243

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 AM CDT Fri Sep 13 2024

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM MIDDLE
TENNESSEE TO THE FLORIDA PANHANDLE...

...SUMMARY...
A marginal tornado threat is expected to develop this morning and
afternoon across parts of Alabama, western Georgia and middle
Tennessee. Isolated damaging to severe gusts will be possible in
parts of Alabama, southwest Georgia and the Florida Panhandle.

...Synopsis...
In mid/upper levels, the CONUS portion of the large-scale pattern
this period will be characterized by a "dirty" Rex block in the
East, and troughing in the West. The block will be composed of an
anticyclone drifting eastward over the Upper Great Lakes, and a
small, deep-layer cyclone -- resulting from the merger of a weak,
midlatitude, mid/upper-tropospheric low with the low/middle-level
remnants of post-tropical cyclone Francine -- centered currently
near BVX. This low should weaken gradually and meander slowly over
the Mid-South, possibly drifting east-southeastward back across the
MEM area through the period, but with negligible movement on the
synoptic scale.

In the northern stream, a mid/upper-level cyclone -- evident in moisture-channel imagery over southern SK -- will eject
northeastward to northern MB and devolve to an open-wave trough by
12Z tomorrow. In its wake, broadly cyclonic flow aloft, with mostly
minor embedded shortwaves/vorticity maxima -- will cover the
northwestern 1/4 of the CONUS. To its east, midlevel DCVA/ascent
from a weak trough trailing the cyclone, combined with low-level
warm advection and gradual moistening, will support general thunder
potential over portions of the northern Plains to upper Mississippi
Valley.

At the surface, 11Z analysis showed a wavy, quasistationary to warm
front extending from off the SC Coast across southern GA and
eastern/northern AL, intersecting a weak cold front there, then as
an occluded front into the low over AR. This boundary should drift
diffusely northward through the period, while weakening. A
stationary to slow cold front was drawn from southern MB across
central ND and western SD, and should drift eastward over the
central Dakotas today through tonight.

...Southeast...
Isolated, mostly short-lived supercells will be possible today,
mainly in a belt of low-level convergence from parts of central/
eastern AL and western GA into the Tennessee Valley, with a marginal
tornado threat. Farther south, in weaker shear (but greater
instability), a few of the stronger cells or small clusters may
produce damaging gusts.

A corridor of relatively maximized low-level shear/SRH remains near
the old, diffuse warm-frontal zone well southeast of the center of
Francine's remnants. Both that and a moisture/buoyancy axis to its
west (centered roughly over the axis of the outlooked corridor)
should move little today, given the slow filling and lack of motion
of the related deep-layer cyclone over the Mid-South. Rich low-
level moisture will persist in this corridor, with surface dewpoints
commonly in the 70s F, and low LCLs. Weaknesses of both surface
winds and midlevel flow will sandwich a 35-40-kt east-southeasterly
to southeasterly LLJ that keeps hodographs somewhat enlarged and
effective SRH in the 150-300 J/kg range over eastern/northern AL
into southern mid TN. With some localized help from boundaries
(outflow or differential-heating), a brief tornado is possible. A
few of the most vigorous, water-loaded downdrafts will be capable of
localized strong to marginally severe gusts, especially over
southern areas where peak MLCAPE may reach about 2000 J/kg.
Activity generally should weaken this evening and overnight as the
airmass stabilizes and the remnants of Francine continue to decay.

..Edwards/Mosier.. 09/13/2024

$$
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ACUS01 KWNS 141244
SWODY1
SPC AC 141242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Sat Sep 14 2024

Valid 141300Z - 151200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTH-CENTRAL PLAINS...

...SUMMARY...
Thunderstorms capable of isolated severe gusts and hail will be
possible over parts of the north-central Plains.

...Synopsis...
Blockiness in the eastern CONUS will continue to dominate the
large-scale, mid/upper-level pattern through the period. An
anticyclone will drift eastward to southeastward over the Great
Lakes, poleward of a broad belt of low heights and several embedded
vorticity maxima extending from the lower Mississippi Valley to
offshore from the Carolinas. One of those perturbations will be the
decaying remnants of a merger of a midlatitude mid/upper low with
the remnants of Francine. This feature is forecast to drift
erratically eastward to southeastward over the Mid-South,
contributing to convective potential over a broad area of the
Southeast, but with wind fields and lift too weak to support
organized severe potential.

Farther west, synoptic-scale height rises are forecast across most
of the central/northern Plains, as a strong trough digs south-
southeastward near the BC Coast and forms a 500-mb low near UIL at
the end of the period. By then, associated cyclonic flow should
cover a large part of the CONUS west of the Rockies, as well as for
several hundred miles off the West Coast.

The 11Z surface analysis showed a low over northern MS (associated
with the remnants of Francine) with an occluded front arching across
AL to a triple point near MGM, a warm front across southern GA, and
a cold front across the western FL Panhandle. These boundaries
should become more diffuse with time today as the deep-layer cyclone
above the low continues its gradual degradation. Meanwhile, a
quasistationary front from east-central ND across central SD to
southwestern NE should weaken through the day, but with a remnant trough/convergence zone lingering near the present position. A weak
surface low should form farther west today, in northeastern WY east
of GCC, then migrate eastward into western SD toward RAP tonight.

...North-central Plains...
Isolated to scattered thunderstorms are expected to develop this
afternoon, in a narrow corridor of relatively maximized low-level
convergence (corresponding to the weak front/trough) and favorably
strong surface heating east through southeast of the low. Isolated
severe gusts and hail will be possible as convection proceeds across
SD and perhaps into southern ND this evening, before encountering
progressively more-stable low-level conditions with a decreasing
severe threat. A weak perturbation apparent in moisture-channel
imagery over east-central WY should move northeastward across the
western NE Panhandle to southwestern/south-central SD by mid/late
afternoon, and may contribute subtle large-scale ascent to the
environment. Still, with broader, ambient height rises superimposed
on that, considerable mesoscale timing/location uncertainty remains
on the most probable initiation zone within the southern part of the
outlook area. The later initiation occurs, the farther north the
unconditional severe-threat area will be.

Activity should move north-northeastward into a corridor of
favorable moisture and buoyancy, with peak MLCAPE in the 500-1500
J/kg range, atop a well-mixed subcloud layer. Greater lift and more
backing of low level flow will be present over the SD part of the
outlook, spreading northward into southern ND with time this
evening, and supporting conditional potential for upscale growth of
activity initiating in a hotter boundary layer near the Badlands.
Stronger capping and weaker convergence over western NE cast some
doubt as to formation and convective coverage in the Sandhills,
though the environment will be favorable for marginal severe there
as well. Modest low/middle-level winds nonetheless will veer
strongly with height, leading to 25-35-kt effective-shear magnitudes
in support of some organization.

..Edwards/Mosier.. 09/14/2024

$$
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ACUS01 KWNS 151252
SWODY1
SPC AC 151250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Sun Sep 15 2024

Valid 151300Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Thunderstorms capable of isolated severe gusts and hail will be
possible today across parts of the central and northern High Plains.

...Synopsis...
In mid/upper levels, a blocky longwave pattern will remain over the
CONUS, with amplifying troughing in the West and a Rex configuration
in the East. Cyclonic flow already covers most of the land west of
the Rockies. That will continue but with backing of the flow aloft,
as a cyclone now centered over Vancouver Island strengthens and digs south-southeastward down the West Coast. By 12Z tomorrow, the
associated 500-mb low should be located near OAK, with strongly
difluent flow and modest ridging over the High Plains from eastern
NM to MT. The southern part of a weak shortwave trough -- evident
in moisture-channel imagery from UT to eastern AZ -- should cross CO
today and reach the eastern border of WY to near GLD by 12Z, likely
enhanced from this evening onward by convectively generated
vorticity.

A mid/upper anticyclone now over the Lower Great Lakes will stretch
eastward and open up to that direction around the end of the period.
The base of the eastern pattern block will be composed of a broad,
nearly zonal height weakness anchored by:
1. The decaying remains of Francine, long merged with a mid/upper
low, and forecast to drift erratically over the Mid-South while
weakening further;
2. An intensifying, deep-layer cyclone with low-level manifestation
as a deepening wave cyclone along a frontal zone, offshore from the
Carolinas.

The 11Z surface analysis showed a wavy, quasistationary frontal zone
attached to a strengthening low located roughly south of EWN and
east of SAV. The front extended across northern FL to the western
FL Panhandle and southwestern AL. A remnant low was drawn well
inland over northern MS, connecting to the Gulf boundary via an
occluded front. These features should move little through the
period, but with further weakening of the western low, and
intensification of the eastern one. Elsewhere, a lee trough and
dryline either overlapped, or were drawn within less than 100 nm
apart, near the eastern border of WY, eastern CO, the northern/
western TX Panhandle, and east-central/southeastern NM. The dryline
should shift somewhat eastward today amid diurnal heating.

...Central/northern High Plains...
Isolated to widely scattered thunderstorms are possible across a
large part of the Rockies, Intermountain West, and Desert Southwest
today. Some of this activity will mature atop deep, well-mixed
boundary layers of desert valleys and the High Plains, with non-zero
potential for a strong-severe gust. The most concentrated/organized
potential for gusts near to above severe limits, as well as marginal
hail, still appears to be over portions of the central High Plains
into the Black Hills and vicinity, near the lee trough/dryline.
East of that, low-level moisture will be relatively maximized in a
return-flow airmass of predominantly continental origin, with a
north-south belt of 50s to mid 60s F surface dewpoints. Where the
western part of that moisture coincides with strong surface heating,
and underlies the eastern part of the EML, a north-south corridor of
MLCAPE in the 1500-2500 J/kg range should develop, with 500-1500
J/kg extending into the more deeply mixed regime nearest the lee
trough. East of the trough, considerable veering of winds with
height is expected, with some low-level hodograph enhancement
potentially moving 0-3-km SRH to near 150 J/kg, but lack of stronger
midlevel flow will temper overall shear.

...Coastal NC, extreme eastern SC...
Many progs deepen the low-level cyclone and transition it to
subtropical or tropical character through the end of day 2, while
eroding the frontal zone's baroclinicity; however, inconsistency
among models is high. The most aggressive among the synoptic and
CAM guidance with the speed of the transition and approach to the
coast (e.g., 06Z GFS and 00Z ARW high-res window respectively) show
favorably large low-level shear, but barely have surface-based
effective inflow onshore at the end of the period, with greatest
convective coverage and buoyancy still offshore. As such, the
associated coastal tornado threat still appears too low and
conditional to outlook until day 2 (after 16/12Z). Potential for
faster/deeper development and shoreward translation of the low will
continue to be monitored for onshore supercell threat the last few
hours of day 1. See latest NHC tropical outlook for guidance on
overall development potential with this system.

..Edwards/Mosier.. 09/15/2024

$$
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ACUS01 KWNS 161248
SWODY1
SPC AC 161246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Mon Sep 16 2024

Valid 161300Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE EASTERN
CAROLINAS AND PARTS OF THE NORTHERN PLAINS...

...SUMMARY...
A tornado threat exists in the eastern Carolinas. Thunderstorms
capable of severe gusts and large hail are expected today in parts
of the northern Plains. Isolated severe wind and hail are expected
in parts of the Four Corners and Great Basin.

...Synopsis...
A highly amplified pattern is expected in mid/upper levels, anchored
by two cyclones:
1. A purely cold-core, midlatitude circulation initially centered
over northern CA, with accompanying cyclonic flow covering most of
the CONUS from the Rockies westward. Equatorward progression of
this feature is about done, and the 500-mb low should pivot eastward
across the RNO area by 00Z, then east-northeastward toward EKO
overnight. In the downstream difluent flow, a shortwave trough is
apparent in moisture-channel imagery over the western Dakotas. This
feature should move northeastward to southwestern MB by 00Z, then to westernmost parts of northwest ON overnight.
2. What is now a small, deep-layer circulation just offshore from
ILM and MYR, designated Potential Tropical Cyclone 8 by NHC as of
this writing. This system may become subtropical or tropical before
moving inland later today, per NHC discussions. Regardless of
whether it is named, the system will offer some tornado potential
(below). The associated mid/upper low is progged to become better
defined through the day and moving farther inland, with the
low-level center tracking not far behind.

As the surface, aside from PTC 8 and its attached frontal zone, the
11Z analysis showed a quasistationary front extending northeastward
from a low near SHR, across southeastern MT to north-central ND,
behind the outflow of a mass of ongoing convection over ND. The
outflow boundary should act as the effective frontal zone for this
region, as it moves slowly eastward over ND and north-central SD
before likely stalling around midday.

...Eastern Carolinas...
A zone of enhanced low-level gradient flow is apparent north through
northeast of the center of PTC 8, over coastal sections of NC and
westward past MYR. This is related both to the cyclone itself and antecedent/post-frontal high pressure from north of the baroclinic
zone upon which this low developed. The synoptically driven
baroclinicity is expected to continue to decrease (frontolysis),
especially if this low becomes tropical. However, some mesoscale
baroclinicity will remain due to persistent rain north of the old
front, and a lack of precip -- combined with a high-theta-e,
maritime/tropical airmass to its south and southeast.

This airmass should shift northward as the low moves inland, and
support potential for inland penetration of enough moisture and
limited diurnal heating to enable 500-1000 J/kg MLCAPE today, away
from areas of continual/persistent rainfall. In an environment
where LCLs are low and low-level shear and SRH already are favorable
(per VWP from ILM and MHX), the tornado threat will be tied directly
to a combination of
1. Sufficient surface-based destabilization on the mesobeta scale,
in that transition zone where flow still is backed enough to keep
hodographs large, and
2. Formation of supercell(s) and their ability to remain in the
favorably buoyant/backed-flow slot long enough to mature and
produce.

See SPC mesoscale discussion 2070 for marginal, near-term potential
near and north of center. Through the day, the effective warm-
frontal regime is expected to shift northward up the coastline and,
to some extent, areas around the Sounds, so a small unconditional
5%/"slight risk" has been introduced in those areas. Tonight into
tomorrow morning, as the center penetrates deeper inland away from
the most favorable airmass and weakens considerably, and as diabatic
cooling reduces instability at the surface, the tornado potential
should diminish.

...Northern Plains...
A large area of precip and convection is ongoing across much of west-central/central and northeastern ND, with embedded strong/
isolated severe thunderstorms capable of gusts and hail. This
activity is reinforcing/reorienting the antecedent baroclinic zone
across the area, and may persist northeastward into the remainder of northeastern ND and northwestern MN through midday with a continued
threat for isolated severe. Additional development is possible
along the outflow-modulated boundary, both in the near term and
through the afternoon, ahead of the shortwave trough, and in the
area of related maximized lift (both convective-scale on the
boundary, and broader-scale in the midlevel DCVA).

The airmass south and east of the boundary should heat diurnally,
steepening the low/middle-level lapse rates amidst favorable 60 F
surface dewpoints. This should support peak/preconvective MLCAPE in
the 1500-2500 J/kg range, along with veering flow with height.
However, lack of stronger midlevel flow limits deep shear, keeping
progged effective-shear magnitudes generally under 35 kt. The most
probable convective mode appears to be a mix of multicells and messy supercells. Convection-allowing progs that most-closely depicted
the current state (which has not included the underdone hourly HRRR
for most of the night) reasonably show a lack of substantial
destabilization north of the boundary, except perhaps for some
elevated hail potential this evening. Convective coverage on ether
side of the boundary may increase for a few hours this evening in
response to enhancement of moisture, shear and storm-relative flow
provides by the LLJ.

...4 Corners/Great Basin...
A broad arc of combined baroclinic and large-scale ascent is
expected to extend across the near-eastern to far-southeastern
sectors of the mid/upper cyclone, supporting episodic, widely
scattered to scattered thunderstorms throughout much of the period.
Where this activity encounters diurnally/diabatically destabilized
boundary layers, characterized by deep mixing with related
maximization of lapse rates and DCAPE, and at least marginal CAPE
above, isolated severe gusts will be a threat. The potential for
high-based supercells amidst greater shear to the southeast, across
the Four Corners area, suggest isolated severe hail also will be
possible there.

..Edwards/Mosier.. 09/16/2024

$$
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ACUS01 KWNS 171207
SWODY1
SPC AC 171206

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0706 AM CDT Tue Sep 17 2024

Valid 171300Z - 181200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS...

...SUMMARY...
Thunderstorms capable of severe wind gusts and isolated large hail
will be possible this afternoon and evening across parts of the
central and northern High Plains.

...High Plains/Central and Southern Rockies...
Water-vapor imagery early this morning shows a potent mid-level low
and associated trough centered over northeast NV. This feature will
become negatively tilted and move into the High Plains late today
while the low moves east-northeast reaching southeast MT Wednesday
morning. Strong attendant forcing for ascent will overspread the
High Plains this afternoon into the early evening with an
accompanying 50-60 kt 500-mb speed max moving into CO and eventually
western NE/SD. In the low levels, a lee trough will sharpen with
southerly flow maintaining a fetch of seasonably adequate moisture
(50s deg F surface dewpoints) into the High Plains.

Ahead of the approaching trough, partial clearing will result in
strong surface heating this afternoon over the central High Plains.
MLCAPE is expected to peak near 1500 J/kg from eastern Colorado
northward into western Nebraska. Initial storm activity late this
morning through the early afternoon will develop over the high
terrain of CO/northern NM and move/develop east into richer moisture
by mid-late afternoon. The increasing large-scale ascent coupled
with heating will eventually result in numerous storms mainly in the
form of linear clusters evolving into linear bands of convection by
early evening. The greatest combination of instability, lift
and deep-layer shear is forecast across western Nebraska and
northeast Colorado, suggesting an enhanced threat for severe wind
gusts. Based on some of the latest CAM data, have expanded the
Slight-Risk equivalent wind probabilities farther south into
northeast NM/northwest TX Panhandle. Some consideration was given
to expand the ENH Risk into southwestern SD, but the later timing of
storms lends enough uncertainty to preclude this change this outlook
update.

...Northern High Plains...
Ahead of the approaching mid-level low, divergent south to
south-southeasterly flow will be in place across the northern
Rockies and northern Plains. During the afternoon, thunderstorms
will develop in the north-central Rockies and move north to
northeastward across the northern High Plains. An axis of moderate
instability is forecast by afternoon from the Dakotas northwestward
into northeast Montana. As large-scale ascent and moderate
deep-layer shear overspread the northern High Plains late this
afternoon and evening, organized storms will be possible. Severe
wind gusts and isolated large hail will be the primary threats.

...Eastern Florida...
A mid-level trough will move across the eastern Gulf of Mexico
today, as an associated surface trough moves across the Florida
Peninsula. Surface dewpoints in the lower to mid 70s F, along with
surface heating will contribute to moderate instability by
afternoon. As surface temperatures warm today, scattered
thunderstorms are expected to develop along and ahead of the surface
trough. RAP forecast soundings at 21Z in eastern Florida have
MLCAPE in the 2000 to 3000 J/kg range, with 0-6 km shear around 20
knots. This, combined with steep low-level lapse rates could be
enough for a marginal threat for locally severe wind gusts.

..Smith/Mosier.. 09/17/2024

$$
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ACUS01 KWNS 181235
SWODY1
SPC AC 181233

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Wed Sep 18 2024

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID MISSOURI VALLEY NORTHWARD INTO EASTERN SOUTH DAKOTA AND
WESTERN MINNESOTA...

...SUMMARY...
Thunderstorms capable of severe wind gusts and isolated large hail
are possible today across parts of the eastern Dakotas and Minnesota
southward in the mid Missouri Valley. A marginal severe threat will
also be possible in parts of the central and southern Plains.

...Northern Plains/Upper Mississippi Valley/Mid Missouri Valley...
Water-vapor imagery depicts a mid-level low over southeast MT this
morning and this feature will continue northeastward during the
period and reach southeastern SK by early Thursday morning. A
mid-level ridge extending northward from the northwest Gulf Coast
into the upper MS Valley will slowly shift eastward into the Upper
Great Lakes. A ribbon of stronger southwesterly mid-level flow will
extend from southern CA through the central High Plains and wrapping cyclonically through the eastern Dakotas and into southern Canada.

In the low levels, a surface trough will be the primary feature of
interest with a plume of 60s deg F dewpoints extending northward to
the east of the boundary from the southern Great Plains into the
Upper Midwest. In wake of early day dissipating shower/thunderstorm
activity (e.g., eastern Dakotas, southern KS), heating of an
adequately moist boundary layer will result in moderate
destabilization by mid afternoon (1500-2500 J/kg SBCAPE). Isolated
to scattered thunderstorms are forecast within a zone of 25-40 kt
0-6 km shear. Some model guidance varies on storm coverage across
the Slight Risk (isolated vs. scattered) but forecast sounding
profiles indicate a risk for organized storms mainly in the form of
organized multicells and supercells. Hail/wind may accompany the
stronger storms during the late afternoon through the early evening
before this activity begins to weaken.

Further south into the southern and central Plains, low-levels are
forecast to be drier near the surface trough, with dewpoints
expected to be mostly in the upper 50s and lower 60s F. Warmer
mid-level temperatures and limited large-scale ascent than farther
north will likely contribute to tempering the overall intensity of
the updrafts and resultant severe intensity/coverage. Models
suggest perhaps locally higher storm coverage and resulting
severe-wind threat from the TX Panhandle north-northeast into far
southern KS during the late afternoon/early evening.

..Smith/Mosier.. 09/18/2024

$$
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ACUS01 KWNS 191252
SWODY1
SPC AC 191251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Thu Sep 19 2024

Valid 191300Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
MINNESOTA...IOWA AND WESTERN WISCONSIN SOUTHWARD INTO EASTERN KANSAS
AND WESTERN MISSOURI...

...SUMMARY...
Scattered severe thunderstorms are possible across central/eastern
Minnesota, Iowa, and western Wisconsin. A couple tornadoes, isolated
large hail, and damaging winds may occur. An area of locally severe
gusts and hail may also develop over parts of eastern Kansas,
southwest Missouri, and into northeast Oklahoma.

...Synopsis...
Early morning water-vapor imagery shows a slow-moving mid- to
upper-level low near the SK/MB/Dakotas border. A negatively tilted
shortwave trough will move across the Dakotas and MN through the
day. A belt of strong (40-50 kt) 500mb flow will extend through the
base of the trough from NE wrapping cyclonically through the Upper
MS Valley into western ON and to the northwest of a flattening ridge
over the mid MS Valley/southwest Great Lakes. Farther south, weaker
west to northwest winds will encompass an area around a southern
Plains upper high from KS/OK into MO and AR. In the high levels,
flow will be strongest across the central Plains, with weakening
winds over the northern Plains/upper MS Valley.

In the low levels, a cyclone will develop northeastward from
southeast SK into central MB by early Friday morning, while a cold
front moves into MN/western IA by mid afternoon, with frontolysis
expected during the latter part of the period. A wind shift/surface
trough will also extend southward across eastern KS and into
northern OK. Ahead of the aforementioned boundaries, southerly flow
will maintain a plume of mid to upper 60s F dewpoints.

...MN/IA/WI...
Scattered weak, elevated storms from the lower MO Valley northward
into MN/WI will gradually move east this morning and likely
dissipate by midday. Cloud breaks and clearing in their wake will
contribute to appreciable heating and moderate to strong buoyancy
developing from near the MO River in western IA northward into MN.
Forecast soundings show 2500-3000 J/kg MLCAPE with a veering and
strengthening wind profile into the mid levels. A broken band of quasi-discrete storms (including supercells) is forecast to develop
from MN southward into at least northern IA. The risk for a couple
of tornadoes may be highest from MN into northern IA where effective
SRH may exceed 200 m2/s2. A couple of stronger supercells may also
develop into western/southwest IA per recent HRRR model trends.
Given the northward lifting of the shortwave trough, and increasing
inhibition east of the MS River, the primary threat should remain
relatively narrow.

...Eastern KS into western MO and into OK...
Widely scattered thunderstorms are ongoing this morning from
south-central into northeast KS. Much of this activity will likely
dissipate but a few residual storms may continue or regenerate on
outflow over parts of western MO later this afternoon. Strong
heating and the steepening of 0-3 km lapse rates will favor the
development of other isolated to widely scattered storms later this
afternoon near the wind shift. 12 UTC regional raobs sampled warm
mid-level temperatures (around -1 deg C at 525 mb at Norman, OK).
These warm midlevel temperatures will limit the overall magnitude of instability. However, lengthy mid to upper level hodographs will
support storm organization with any robust/established updraft. The
stronger storms will potentially be capable of a risk for severe
gusts and perhaps large hail.

..Smith/Mosier.. 09/19/2024

$$
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ACUS01 KWNS 201245
SWODY1
SPC AC 201243

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 AM CDT Fri Sep 20 2024

Valid 201300Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHWEST
LOWER MICHIGAN INTO PARTS OF ILLINOIS...INDIANA...AND SOUTHEAST
MISSOURI...AND OVER PARTS OF THE CENTRAL PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms are possible during the late
afternoon over parts of southwest Lower Michigan, Illinois, Indiana,
and southeast Missouri. Isolated strong to severe storms are also
possible across parts of the south-central Plains.

...Synopsis...
Shortwave trough currently moving through WI and Upper MI will
continue eastward through the Upper Great Lakes region today.
Another shortwave trough will follow quickly in its wake,
progressing across Alberta, Saskatchewan, and Manitoba, and adjacent
portions of MT and the northern Plains this evening and overnight.
Father south, a deep upper low with seasonably cold mid-level
temperatures will move from southern CA into AZ. Progression of this
low will dampen the northwestern periphery of the upper ridging
centered over TX.

A surface low attendant to this WI/Upper MI shortwave trough is
currently near the IA/WI/IL border intersection, with weak cold
front extending southwestward from this low to another subtle
surface low over the central OK/KS border. Surface troughing
continues southwestward from this secondary low, but this portion of
the boundary has taken on more warm-front-like characteristics over
the past several hours (evidenced by the dewpoint increase of 3-4
deg F over the past 3 hours across the eastern TX/OK Panhandle).
Enhanced westerly/southwesterly flow aloft attendant to both the
central Canada/MT shortwave trough and CA upper low will contribute
to sharpening surface lee troughing throughout the day and into this
evening.

...Central Plains...
Low-level moisture is expected to advect northward/northwestward
throughout the day as Thursday's cold front returns northward as a
warm front. As a result, low to mid 60s dewpoints will likely be in
place across south-central/southeast KS during the late afternoon.
Dewpoints will likely be in upper 50s farther west in southwest KS,
with notably drier conditions across the adjacent TX/OK Panhandles
where downsloping southwesterly surface winds are likely.

Southwesterly flow aloft ahead of the approaching upper low will
advect steep mid-level lapse rates northeastward through the
southern High Plains into western portions of the central Plains.
Modest buoyancy is anticipated during the late afternoon where these
lapse rates overlay the more favorable low-level moisture across
southern KS. Limited large-scale ascent and low-level confluence
near the warm front is anticipated over this region as well, with
isolated to widely scattered high-based thunderstorm anticipated.
Vertical shear will be modest, but still strong enough for
persist/organized storm structures, and the potential for some
strong gusts with the more robust storms. Some isolated hail is also
possible over south-central KS where buoyancy is maximized.

Low-level moisture will continue advection northward during the
evening and overnight, with a strengthening low-level jet
anticipated as well. Consequently, additional thunderstorm
development is expected after 04Z over northeast KS and adjacent far
southeast NE and northwest MO. Isolated hail is possible with the
strongest storms.

...Southwestern Lower MI into IN, IL, and southeast MO...
Upper 60s to low 70s dewpoints are expected from southwest Lower MI southwestward across western IN, southern IL, and southeast MO.
Daytime heating of this moist low-level air mass will yield a
moderately unstable and uncapped air mass ahead of the approaching
front, and thunderstorm development is anticipated as the front
interacts with this airmass. Moderate vertical shear will be in
place, but poor lapse rates and notable mid-level dry air could make
updraft maintenance difficult. As such, a more multicellular storm
mode is anticipated. Highest storm coverage is expected over
southwest Lower MI and western IN, with warm mid-level temperatures
likely limiting coverage across southern IL and southeast MO.
Locally strong gusts will be the primary severe risk, with isolated,
marginally severe hail possible as well.

..Mosier/Broyles.. 09/20/2024

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ACUS01 KWNS 211246
SWODY1
SPC AC 211245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Sat Sep 21 2024

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Scattered severe storms capable of all hazards are possible this
afternoon and evening across portions of the southern High Plains.

...Southern High Plains...
Water-vapor imagery this morning shows a potent mid- to upper-level
low and associated trough moving east across AZ. An associated
70-kt 500-mb speed max will round the base of the trough and move
into central NM by early evening before weakening overnight as it
moves into the TX Panhandle. Southerly low-level flow will maintain
a fetch of seasonably rich moisture across the region today
(reference 12 UTC Del Rio, TX and Midland, TX raobs; 18.3 and 14.9
g/kg lowest 100-mb mean mixing ratios, respectively). Early morning
surface analysis places a cold front pushing southward over the
central High Plains and this boundary will reach northeast NM and
parts of the Panhandles late this afternoon/early evening.

Some continuation of ongoing shower/thunderstorm activity may
continue through the morning across eastern NM into the TX
Panhandle, lending some uncertainty in airmass
destabilization/recovery in wake of this convection. 06z model
guidance (particularly the NAM) seemed to reasonably depict the
low-level moisture plume emanating from the Rio Grande
Valley/Edwards Plateau northwestward into the southern High Plains.
Steep 700-500 mb lapse rates (7.5 to 8.0 deg C/km) sampled this
morning from Albuquerque and Midland will combine with daytime
heating to yield a moderately unstable airmass by afternoon across
eastern NM into west TX. Increasing large-scale deep-layer ascent
approaching from the west and frontal/orographic lift will likely
contribute to scattered thunderstorms developing relatively early
this afternoon. Forecast hodographs indicate supercells will evolve
within this environment. The risk for large hail/severe gusts will
likely accompany the stronger storms, and a threat for a few
tornadoes may be realized later this afternoon/early evening from
eastern NM into parts of adjacent west TX.

...Upper Midwest to Mid MO Valley...
A northern-stream short-wave trough will continue to move eastward
from southern MB/Dakotas into MN/northwest ON during the period.
A surface cold front will advance into MN-western IA-southern NE by
midday, before accelerating east into the Upper Great Lakes, while
the trailing portion of the boundary pushes south-southeast into
central KS by early to mid afternoon. This boundary will serve as
the focus for potential convective development during the late
afternoon, though surface heating is not expected to be particularly
strong ahead of the wind shift. With the strongest forcing expected
to spread across northwest ON, convection may be more isolated along
the front trailing across the Upper Midwest. Even so, some hail/wind
threat will exist with this activity which should peak in intensity
during the early evening.

...Western PA into western VA...
Weak short-wave trough will dig southeast across the upper OH Valley
later this afternoon with modest mid-level northwesterly flow
expected to extend across western PA/VA. This feature will encourage
scattered convection later this afternoon along a frontal zone that
will be draped across the Delmarva-western PA into western NY.
Models suggest scattered storm coverage and forecast soundings would
imply some of the stronger storms being capable of an isolated risk
for wind damage (50-60 mph) and perhaps some hail. This activity
will likely diminish by early evening coincident with nocturnal
cooling.

..Smith/Broyles.. 09/21/2024

$$
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ACUS01 KWNS 221240
SWODY1
SPC AC 221238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Sun Sep 22 2024

Valid 221300Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
WEST TEXAS THROUGH THE OZARKS AND INTO THE LOWER OHIO VALLEY...

...SUMMARY...
Isolated severe thunderstorms are possible from west Texas to
western Kentucky.

...West Texas into the Ozarks and lower OH Valley...
An upper low over CO will continue to slowly weaken as it migrates
eastward into the central Great Plains through early Monday morning.
A belt of moderate southwesterly mid-level flow will reside in
between the closed circulation and a flattening anticyclone centered
over the northwest Gulf of Mexico. In the low levels, a south and southeastward movement of a surface front is forecast through today
as it moves through the Corn Belt and areas farther southwest in the
southern Great Plains.

Showers and isolated thunderstorm activity this morning extends
along and behind the front from OK northeastward into the lower MO
Valley and western Great Lakes. Considerable cloud cover will
contribute to limited diurnal heating, especially from near the Red
River northeastward into the Ozark Plateau. Morning surface
analysis shows a reservoir of lower 70s deg F dewpoints over the
Edwards Plateau (reference the 12 UTC Del Rio, TX raob showing a
capped but deep moist layer) with 65-70 F farther northeast from OK
through the Ozarks. Forecast soundings later this afternoon
indicate 500-2000 J/kg MLCAPE---supporting a risk for a few stronger thunderstorms near/behind the boundary/wind shift. Strong to
locally damaging gusts (50-60 mph) and perhaps hail up to around 1
inch in diameter are possible mainly this afternoon into the early
evening.

..Smith/Broyles.. 09/22/2024

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ACUS01 KWNS 231236
SWODY1
SPC AC 231235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Mon Sep 23 2024

Valid 231300Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE OZARKS
TO THE OHIO/TENNESSEE VALLEYS REGION...

...SUMMARY...
Isolated strong to severe thunderstorms are possible mainly this
afternoon into the early evening from the Ozarks into parts of the
Tennessee and lower Ohio Valleys.

...Ozarks into TN/OH Valleys and southern Appalachians...
Water-vapor imagery this morning shows a digging trough over eastern
MT with it forecast to move into the Dakotas this afternoon. A
positive-tilt mid-level trough over the central Plains will move
east and deamplify over the MS Valley overnight. This evolution is
expected to aid weak surface wave/low development along the synoptic
front over the Ozarks before moving to the IL/IN border by early
Tuesday morning. Ongoing showers/thunderstorms over southeast MO
will continue east into the lower OH Valley this morning and temper destabilization through at least midday. In its wake, models
indicate MLCAPE in excess of 1000 J/kg developing from AR into
western KY/TN, coincident with modest 0-6km bulk shear. The surface
boundary will serve as the focus for scattered convection later
today with some of the stronger storms potentially capable of a
localized severe threat. This activity is expected to diminish
during the evening.

Farther east, isolated to scattered thunderstorms will probably
develop near the ridge tops of the southern Appalachians and
adjacent parts of the Carolinas Piedmont this afternoon. Moist low
levels coupled with heating will result in around 1000 J/kg MLCAPE.
Some modest multicell organization may occur due to adequately
strong upper-level westerly flow. However, weak flow in the lowest
5 km and modest lapse rates will probably temper the overall
potential for localized strong gusts (40-55 mph).

..Smith/Broyles.. 09/23/2024

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ACUS01 KWNS 241243
SWODY1
SPC AC 241242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Tue Sep 24 2024

Valid 241300Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
KENTUCKY INTO SOUTHERN OHIO AND WEST VIRGINIA...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible mainly this
afternoon across portions of the Ohio and Tennessee Valleys into the central/southern Appalachians. A few strong/severe storms are also
possible across portions of the southern Plains.

...Ohio and Tennessee Valleys to southern Appalachians...
Water-vapor imagery this morning shows a mid-level vorticity maximum
moving across the middle MS Valley and into the OH Valley. A belt
of moderate to strong southwesterly 500-mb flow (25-50 kt) will
overspread KY and the surrounding states, with the strongest flow
generally within the Slight Risk bounds. Bands of showers/weak
thunderstorms are ongoing this morning from middle TN into OH, and
in a separate area over eastern IL immediately ahead of the surface
low. This low will migrate east-northeast into southern Lower MI by
early evening with a frontal zone extending south-southwest into the
Mid South. In wake of the early morning convection, some cloud breaks/destabilization is forecast with upwards of 750-2000 J/kg
MLCAPE from the southern Great Lakes into the southern Appalachian
states. Ample deep-layer speed shear (via mostly southwesterly flow
through the troposphere) will aid in storm organization into
organized multicells and probably several supercells. Only notable
change this outlook update was to include portions of the southern
Great Lakes in low-severe probabilities for potential activity
near/ahead of the surface low. The primary concern across the
general region will likely be damaging winds with the stronger
storms.

...OK vicinity...
An amplifying large-scale trough over the MS Valley will feature a
60-kt 500mb speed max moving southward into the central Great Plains
by early evening on the backside of the upper trough. Left exit
region of this feature will encourage large-scale ascent, and a weak
surface wave/low should evolve over southwest KS/northwest OK by
early afternoon. Strong heating will contribute to 750-1250 J/kg
MLCAPE by mid afternoon across OK with flow veering and
strengthening with height. Elongated hodographs will support the
potential for hail growth with a few of the stronger/sustained
updrafts that evolve. An isolated threat for large hail (1 to 1.75
inches in diameter) and/or severe gusts (60-70 mph) will probably
peak during the 23z-03z period before storms weaken during the late
evening.

..Smith/Broyles.. 09/24/2024

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ACUS01 KWNS 241647
SWODY1
SPC AC 241645

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1145 AM CDT Tue Sep 24 2024

Valid 241630Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF TN/KY/OH/WV AND CENTRAL OK...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible mainly this
afternoon across portions of the Ohio and Tennessee Valleys into the central/southern Appalachians. Severe storms will also be possible
across portions of Oklahoma.

...Ohio and Tennessee Valleys to southern Appalachians...
Have spatially adjusted/expanded the Slight Risk based on
observational trends and somewhat stronger destabilization across
areas such as northern/middle Tennessee. Water-vapor imagery shows a
mid-level vorticity maximum moving across the middle Mississippi
Valley and into the Ohio Valley. A belt of moderate to strong
southwesterly 500-mb flow (25-50 kt) will overspread Kentucky and
the surrounding states. A surface low will migrate east-northeast
into southern Lower Michigan by early evening, where isolated severe
storms are possible, with a frontal zone extending south-southwest
from this low into the Mid South.

In the wake of early morning convection, modest cloud
breaks/destabilization is forecast with upwards of 750-2000 J/kg
MLCAPE from the southern Great Lakes into the southern Appalachians,
with the strongest destabilization expected across Tennessee into
southern Kentucky and possibly the western Carolinas pending the timing/abatement of lingering cloud cover. Regionally, ample
deep-layer speed shear will aid in storm organization into organized
multicells and probably several supercells. Damaging winds will be
the most common hazard, but isolated large hail will be possible,
and some tornado risk may exist as well.

...Oklahoma/North Texas...
Have upgraded portions of central Oklahoma for what is expected to
be a semi-focused regional corridor of large hail potential late
this afternoon and early evening. The region will be influenced by
the immediate backside of a southeastward-moving upper-level trough
centered over the Lower Missouri Valley. A considerably
strengthening cyclonically curved belt of westerlies aloft will
influence Oklahoma, overspreading a relatively moist air mass, with
lower to some middle 60s F surface dewpoints likely to persist
through the diurnal heating/mixing cycle.

Near a deepening surface low and nearby triple point/warm front, at
least isolated storms are expected to develop as early as
mid-afternoon (3-4pm), becoming more probable with a greater
coverage through sunset. Overall buoyancy will not be robust, with
MLCAPE generally not expected to exceed 1000 J/kg later this
afternoon. However, this buoyancy, along with steep lapse rates and
robustly vertically veering wind profiles, accentuated by 35-45 kt northwesterly mid/upper-level flow, should support initial
supercells capable of large hail (potentially golfball size), along
with some potential for damaging wind gusts.

These storms will persist generally southeastward through the
evening into southern/southeast Oklahoma, and probably north Texas
overnight. Overall intensity will tend to wane nocturnally after
sunset, but some severe hail/wind potential will probably linger,
particularly on the west/southwest flank of any evolving clusters of
storms, which will be increasingly elevated to the east of the warm
front.

..Guyer/Lyons.. 09/24/2024

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ACUS01 KWNS 251323
SWODY1
SPC AC 251323

Day 1 Convective Outlook RESENT 2
NWS Storm Prediction Center Norman OK
0823 AM CDT Wed Sep 25 2024

Valid 251300Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
GULF COAST INTO THE SOUTHERN/CENTRAL APPALACHIANS AND FLORIDA PENINSULA...

...SUMMARY...
Isolated severe storms are possible this afternoon from parts of the
Southeast and central/southern Appalachians to the Texas/Louisiana
Gulf Coast. Some tornado threat may develop across the Florida
Peninsula by this evening, in association with Tropical Cyclone
Helene.

...Southeast and southern Appalachians...
Widespread precipitation is expected from parts of the Southeast
into the southern Appalachians, due to the combined influence of the mid/upper-level flow to the west and moisture streaming north from
the Gulf of Mexico and Helene. While this will tend to limit
available buoyancy in some areas, strong to locally severe storms
will be possible with initial development, with preconvective MLCAPE
of around 1000 J/kg possible. This will generally be coincident with
favorable deep-layer shear, especially across the southern
Appalachians vicinity where a few supercells could occur pending
sufficient destabilization. Locally damaging wind gusts and perhaps
a tornado could accompany the strongest storms, before low/mid-level
lapse rates and buoyancy become increasingly weak with time, and an outflow-reinforced front sags southward across the region.

...Texas Gulf Coast/Middle Gulf Coast...
Somewhat stronger diurnal destabilization will be possible from
parts of central/east Texas into Louisiana, and perhaps into
Mississippi, with MLCAPE potentially increasing above 1500 J/kg.
Isolated to widely scattered thunderstorm development will be
possible near a southward-moving cold front. Effective shear will
generally range from 25-35 kt, and a few modestly organized storms
are possible. Isolated damaging gusts could accompany the strongest
storms within this regime.

...Florida Peninsula and Keys...
Helene's wind field is forecast to be rather large, especially on
the east side of the circulation, associated with what is expected
to be a strengthening Helene through the afternoon and night.
Reference the National Hurricane Center for the latest Helene
details. This scenario will result in modestly strengthening
low-level shear/SRH across the Florida Peninsula during the day, but
more so into the evening and overnight after the peak diurnal
instability cycle. Instability will likely remain rather weak
overall, and details regarding the intensity of any outer rain bands
remain uncertain. However, some tropical-cyclone tornado threat
could evolve across parts of the Florida Peninsula and Keys, mainly
into tonight.

...Eastern Washington/northern Idaho/northwest Montana...
While buoyancy is expected to remain quite weak, relatively steep
mid-level lapse rates will support thunderstorm potential late this
afternoon through early evening from eastern Washington into
northern Idaho and northwest Montana, in advance of the approaching
shortwave trough. Most guidance suggests that instability will
remain too weak for an organized severe threat, although rather
strong deep-layer flow/shear could support a strong storm or two
with locally gusty winds and small hail. Subsequent outlooks will
reevaluate the possibility of introducing low severe probabilities.

...Upper Ohio Valley to the Lower Great Lakes...
Weak to locally moderate buoyancy may develop later today from parts
of the upper Ohio Valley into the lower Great Lakes region, between
a weakening cold front approaching from the west, and a slow-moving
warm front draped from central Pennsylvania into western New York.
Moderate southwesterly midlevel flow will support effective shear of
35-45 kt, sufficient for storm organization. However, with
persistent cloud cover and mid-level lapse rates expected to remain
rather weak, storm intensity and any attendant severe threat could
be relatively limited. Confidence in sufficient destabilization
remains too low to add severe probabilities.

..Guyer/Broyles.. 09/25/2024
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ACUS01 KWNS 260101
SWODY1
SPC AC 260059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Sep 25 2024

Valid 260100Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHERN APPALACHIANS INTO PARTS OF THE SOUTHEAST AND FLORIDA...

...SUMMARY...
Isolated strong to severe storms are possible this evening from the
southern Appalachians into parts of the Southeast. Some tornado
threat may develop later tonight over Florida, in association with
Hurricane Helene.

...Florida...
Hurricane Helene is forecast to intensify and move north to
north-northeastward across the southeast Gulf of Mexico tonight; see
NHC forecasts/advisories for more information. Helene's large wind
field will continue to overspread the Florida Peninsula and Keys
tonight, with low-level shear/SRH becoming increasingly favorable
for low-topped supercells with a potential tornado threat.
Low-topped supercell potential prior to 12Z Thursday morning remains
uncertain, with inland instability expected to remain relatively
limited. Outer rain bands could begin to affect the western
Peninsula later tonight, while convection may persist near a
convergence zone near the east coast.

...Southern Appalachians vicinity into parts of the Southeast...
Widespread precipitation is ongoing this evening within a corridor
from the FL Panhandle into western NC/VA, but weak to locally
moderate buoyancy persists east of this band, with regional VWPs and
the 00Z RNK sounding depicting vertically veering wind profiles
favorable for organized convection. Generally weak low/midlevel
lapse rates will tend to limit storm intensity, but marginal
supercell potential may persist through the evening, with a threat
of isolated damaging gusts and possibly a tornado.

...Northern ID/northeast WA/northwest MT...
While low-level moisture is limited, steep lapse rates and ascent
attendant to an approaching mid/upper-level shortwave trough are
supporting a high-based storm cluster currently moving across the ID
Panhandle. This cluster has a history of 60-65 mph gusts, and will
move across northwest MT early this evening, with a continued threat
of strong to locally severe gusts.

..Dean.. 09/26/2024

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ACUS01 KWNS 281240
SWODY1
SPC AC 281238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Sat Sep 28 2024

Valid 281300Z - 291200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Synopsis/Discussion...
The mid/upper-level pattern features mean ridging over the West and
troughing in the East. The pattern is anchored by a large, nearly
stacked cyclone -- resulting from the combination of an antecedent
midlatitude low with the post-tropical remnants of Helene. The
cyclone should remain centered over the lower Ohio Valley region, drifting/wobbling erratically eastward over northern KY through the
period, while continuing to fill. The strongest associated mid/
upper-level winds should remain mostly behind a low-level frontal
zone extending from the northern Gulf across northern FL to the
coastal Carolinas. South of the boundary across parts of peninsular
FL, sufficient low-level moisture remains -- amid weak to negligible
MLCINH and a deep troposphere with modest but sufficient lapse rates
for convection. This will support scattered thunderstorms today
over FL, with isolated thunderstorm potential over coastal areas of GA/Carolinas near the boundary. Dry midlevel air and lack of
greater flow/shear should keep severe potential too isolated and
disorganized for an outlook.

Elsewhere, just east of the mean ridge and amid northerly flow very
peripheral to the cyclone, a patch of marginally favorable low/
middle-level moisture should combine with diurnal heating of higher
terrain over parts of northern NM and southern CO. Scattered
showers are expected this afternoon, with isolated to widely
scattered convection extending above a mid/upper-level stable layer
and into icing regions suitable for lightning generation. Isolated thunderstorms also are possible amid weak but sufficient low-level
moisture and instability around parts of the eastern Great Lakes.

..Edwards/Broyles.. 09/28/2024

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ACUS01 KWNS 291230
SWODY1
SPC AC 291228

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 AM CDT Sun Sep 29 2024

Valid 291300Z - 301200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast for today.

...Synopsis/Discussion...
A highly amplified, slow-moving, mid/upper-level pattern will
persist over much of the CONUS, south of a progressive northern
stream near and north of the Canadian border. A norther-stream
trough, nearly synoptic in scale, is apparent in moisture-channel
imagery from central/southwestern BC to near-coastal WA/OR. This
feature should amplify and move eastward across southwestern Canada
and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow.
Weak, basal height falls and modest midlevel moisture will
contribute to the potential for isolated, high-based convection over
portions of UT, some of which may extend deep enough to generate
lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area.

As the northern-stream trough moves away from CA, a formerly cut-off
low now moving ashore into south-central CA will become cut off
again, and drift southward/southwestward back toward the Pacific by
the end of the period. Ridging will weaken greatly over the
northern Plains and Upper Midwest ahead of the northern-stream
trough, but will persist at its root over the Four Corners region.
To its east, a longstanding, stacked, gradually filling cyclone will
drift erratically eastward over the TN/KY border area, possibly
devolving into an open-wave trough by the end of the period.
Associated convection to its east will encounter a relatively warm/
stable layer in mid/upper levels, limiting but not entirely
suppressing potential for convection to reach into icing layers
suitable for lightning. As such, isolated thunder will be possible
from the central Appalachians to the Tidewater. Although warm
midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over
northern FL will support sporadic thunderstorm potential, mainly
from midday through early evening.

..Edwards/Broyles.. 09/29/2024

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ACUS01 KWNS 301239
SWODY1
SPC AC 301237

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0737 AM CDT Mon Sep 30 2024

Valid 301300Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today, though a few strong
storms may affect central/eastern North Carolina.

...Synopsis/Discussion...
The main belt of mid/upper-level, midlatitude westerlies will
continue to traverse the northwestern/north-central CONUS and central/southwestern Canada, buckled cyclonically around a prominent
synoptic trough now located from eastern SK to central MT and
western WY. This trough should phase with another now over central
mainland Arctic Canada by the end of the period, resulting in a
500-mb low over southeastern Nunavut, with trough trailing over
western Hudson Bay, northwesternmost ON, MN, and IA.

Strongly difluent flow aloft will take shape southeast of the
trough, across the Mississippi Valley, the Great Lakes from
Michigan/Huron on down, the Ohio Valley, and much of the
Appalachians. As that occurs, a longstanding, filling, weakening
low now over southwestern WV will devolve today to an open-wave
trough, losing amplitude rapidly and drifting eastward over the
central Appalachians through the period. Part of a basal shortwave trough/vorticity lobe -- now apparent in moisture-channel imagery
over eastern TN -- will eject eastward across northern NC and
southern VA from this afternoon through tonight.

At the surface, 11Z analysis showed a quasistationary front across
northern SC to just south of the southern Outer Banks, extending
from a triple-point low near CAE. This boundary should shift
northward over central/eastern NC through the day. Meanwhile, a
cold front -- related to the strong northern-stream trough -- was
drawn from central/southern MB across southern ND, central SD,
northwestern NE, and southern WY. This front should sweep across
most of the Great Plains and upper Mississippi Valley through the
period, reaching northern Lower MI, IL, southwestern MO, southern
OK, and the TX South Plains by 12Z.

...Central/eastern NC...
Widely scattered showers and thunderstorms are expected to develop
this afternoon over the Piedmont and coastal plain, in an
environment characterized by rich boundary-layer moisture (surface
dewpoints commonly in upper 60 to mid 70s F) very weak ambient
MLCINH easily removed by diurnal heating, but weak mid/upper-level
lapse rates. This will result in 500-1200 J/kg MLCAPE over most of
the area from he Piedmont to the Sounds, beneath a belt of
sufficiently strong mid/upper flow to yield around 35-45-kt
effective-shear magnitudes.

Low-level hodographs over central/eastern NC this afternoon, from
model forecast soundings, reasonably show curvature near the frontal
zone, but with weak speeds in the lowest couple km that
substantially limit SRH and vector shear. However, above 1 km,
hodographs are somewhat long and straight, suggesting the potential
for low-end supercells amidst the mode common multicellular modes.
At this time, forecast shear appears too weak to support an
unconditional tornado-threat area, but the scenario will be
monitored for any mesoscale enhancement to shear (especially along
boundaries) that may introduce such a risk. The gust threat appears
subsevere at this time, though localized gusts approaching severe
limits cannot be ruled out.

..Edwards/Broyles.. 09/30/2024

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ACUS01 KWNS 011227
SWODY1
SPC AC 011225

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0725 AM CDT Tue Oct 01 2024

Valid 011300Z - 021200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Synopsis...
In mid/upper levels, the main belt of westerlies is expected to
remain near the Canadian border through the period, extending across
more of the Great Lakes with time. That will occur as a synoptic-
scale trough -- evident in moisture-channel imagery from a low over
westernmost parts of Hudson Bay across northwestern ON to the upper
Mississippi Valley -- ejects northeastward over northern ON, and
James and Hudson Bays, through the period. This stronger flow will
remain well poleward of thunder potential today near a weakening/
ejecting trough over the Tidewater region, south of a weak front
over FL, and under or south of a weakening synoptic ridge over parts
of CO/NM/AZ. Vertical shear and lapse rates aloft will be too weak
in any of those areas to support organized severe potential.
Locally strong gusts may accompany the high-based convection in AZ,
with a deep/well-mixed subcloud layer, but only modest (5-15 kt)
midlevel easterlies. A cold front sweeping across the Great Lakes,
Ohio Valley, lower Mississippi Valley, and southern Plains, should
encounter a marginally moist/unstable airmass for isolated thunder,
within a band of convection over parts of the eastern Great Lakes.

..Edwards/Dean.. 10/01/2024

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ACUS01 KWNS 021235
SWODY1
SPC AC 021233

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Wed Oct 02 2024

Valid 021300Z - 031200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
The mid/upper-level pattern will be characterized by a belt of
gently difluent, west-northwesterly northern-stream flow from the
Pacific Northwest to the Great Lakes. This flow will weaken
considerably and become much more difluent over the Ohio Valley, mid Mississippi Valley and Appalachians. The strongest flow aloft will
be well-displaced from any substantial low-level moisture/theta-e,
which is expected to remain along and south of a quasistationary
front draped across north-central FL.

Scattered daytime thunderstorms are expected to form along FL East
and West Coast sea breezes, shifting inland as the boundaries
(including outflows from the first generation of convection nearer
the coasts) merge. Weak deep-layer flow and lack of shear will
preclude organized severe potential. Localized strong gusts are
possible in wet downbursts with enhanced lift along colliding
boundaries, 1500-2000 J/kg preconvective MLCAPE, and rich inflow-
layer moisture (surface dewpoints 70s F and PW commonly over 2
inches). Elsewhere, very isolated/brief lightning may occur near
the AZ/NM border and Mogollon Rim, but with barely enough moisture
for convection, coverage is expected to be too small for a 10% area.

..Edwards/Dean.. 10/02/2024

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ACUS01 KWNS 031238
SWODY1
SPC AC 031236

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Thu Oct 03 2024

Valid 031300Z - 041200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
In mid/upper levels, a nearly zonal northern-stream pattern will
prevail either side of the Canadian border, from the Pacific Coast
across the Great Lakes to New England. The main feature perturbing
that belt for this period will be a strongly positively tilted
trough, currently over south-central parts of SK/MB northwestward to north-central AB. This trough will amplify and pivot southeastward/
eastward across northern ON, northern MN and Lake Superior into
tonight. By 12Z, the trailing part of this feature should be moving
across the western U.P of MI, northern WI and central MN. A weak
shortwave trough -- evident in moisture-channel imagery over eastern
OR and southwestern ID -- may reach the Quad Cities area of IA/IL by
12Z tomorrow and phase with the larger trough.

At the surface, 11Z analysis showed a frontal wave low over
northwestern KS, with warm front eastward to west-central/
northwestern MO, and cold front across east-central CO. The low
should migrate eastward through the period, reaching north-central/ northwestern MO by 12Z, with cold front trailing across southern KS,
western OK and the TX South Plains, and warm front extending to
east-central MO and southern IL.

...Mid/upper Mississippi Valley...
Capping and meager boundary-layer moisture will inhibit convective
potential today along/ahead of the front and low. However, an area
of isolated to scattered elevated thunderstorms is possible
overnight northeast of the low, supported by large-scale DCVA/lift
ahead of the ejecting shortwave trough, and warm advection/
isentropic lift to LFC of increasingly moist parcels above the
surface. Activity should be rooted in the 700-800-mb layer, amidst
MUCAPE roughly 500-800 J/kg, and around 35-40 kt effective-shear
magnitudes. This may support small hail, especially early in the
convective cycle when cells are still at least somewhat discrete.
Modes should become messier and precip more expansive fairly
quickly, as inflow-layer moisture and MUCAPE only slowly increase in
the immediate upstream airmass to the southwest. The overall severe
threat appears too limited and conditional for an outlook at this
time.

..Edwards/Dean.. 10/03/2024

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ACUS01 KWNS 041250
SWODY1
SPC AC 041248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Fri Oct 04 2024

Valid 041300Z - 051200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...Synopsis and Discussion...
Elevated thunderstorms ongoing across west-central IL should
continue for a few more hours this morning, aided by modest warm
advection in the 850-700 mb layer and ascent on the southern
periphery of a shortwave trough over the Upper Midwest. With a
mainly linear mode now dominant, severe hail appears unlikely. This
activity should gradually diminish in coverage and intensity through
the remainder of the morning.

Isolated to scattered thunderstorms will be possible today from
parts of the Mid-Atlantic southwestward to the Gulf Coast/Southeast.
Weak flow and related deep-layer shear will limit the overall severe
threat with any convection that develops across these regions. A
pronounced shortwave trough will move across the Pacific Northwest
and northern Rockies/Plains through tonight. While large-scale
forcing and mid-level flow associated with the upper trough passage
will be strong, thunderstorm coverage is expected to remain sparse
due to a rather dry airmass present across these areas.

..Gleason/Dean.. 10/04/2024

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ACUS01 KWNS 050600
SWODY1
SPC AC 050559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Sat Oct 05 2024

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
NORTHERN WISCONSIN AND ADJACENT PORTIONS OF SOUTHERN UPPER MICHIGAN...

...SUMMARY...
Isolated strong to severe thunderstorms may produce hail and gusty
winds across parts of northern Wisconsin into the Upper Peninsula of
Michigan this evening.

...Synopsis...
Flow aloft will remain generally weak over the southern half of the
U.S. today, where upper ridging will prevail. This ridging will --
however -- be interrupted by an elongated/weak trough comprised of
several smaller-scale vorticity maxima, extending from the
southeastern states west-southwestward across the Gulf of Mexico to
northern Mexico.

Farther north, a faster belt of westerly flow will prevail, with an embedded/potent short-wave trough forecast to move across the
northern Plains through the day, and then the Upper Mississippi
Valley/Upper Great Lakes region overnight.

Accompanying the upper trough, a surface low is forecast to advance east-northeastward across the Canadian Prairie, and into
northwestern Ontario through latter stages of the period. A
trailing cold front will shift eastward across the north-central
U.S. and southward across the Plains -- reaching a position from
Lower Michigan southwestward to the Ozarks, and then
west-southwestward across Oklahoma to Far West Texas by Sunday
morning.

...Central and northern Wisconsin north to Lake Michigan...
As a cold front advances across the Upper Midwest area through the
afternoon, a capped boundary layer should hinder convective
development. As the boundary crosses the Upper Mississippi Valley
around sunset, and the upper system advances, the combination of
strong ascent and steepening lapse rates aloft should permit
eventual development of showers and scattered thunderstorms.

With a rather dry -- and nocturnally stabilizing -- boundary layer
expected ahead of the front, convection should evolve within a
slightly elevated but amply unstable layer. Strong southwesterly
flow aloft will provide sufficient shear for organized/rotating
storms -- and thus risk for hail is evident. Additionally, the
strongly dynamic upper system/strong mass response suggests
potential for downward transport of strong flow aloft -- potentially manifesting as severe-caliber wind gusts at the surface. Given the
overall severe risk, will introduce a small SLGT/level 2 risk across
this area, with the primary risk expected to be hail. However,
potential for strong/gusty surface winds may also -- depending upon boundary-layer evolution -- warrant upgrade to 15% probability in
later outlooks.

..Goss/Squitieri.. 10/05/2024

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ACUS01 KWNS 061246
SWODY1
SPC AC 061245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Sun Oct 06 2024

Valid 061300Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN OHIO...WESTERN NEW YORK/PENNSYLVANIA...AND THE NORTHERN WEST
VIRGINIA PANHANDLE...

...SUMMARY...
Isolated to scattered severe thunderstorms should occur this
afternoon and evening from parts of eastern Ohio into western New York/Pennsylvania, West Virginia, and western Maryland. Damaging
winds and hail should be the main threats.

...Upper Ohio Valley into the Lower Great Lakes and Central
Appalachians...
A vigorous upper trough over Ontario and the Great Lakes will
continue advancing eastward across parts of Quebec and the Northeast
today. A related surface low over northern Ontario this morning will
slowly occlude through the day, while a cold front extending across
the upper Great Lakes and Midwest advances southeastward over the OH
Valley and western Mid-Atlantic by this evening. A narrow corridor
of modest low-level moisture will return northward ahead of this
cold front, with surface dewpoints generally in the 50s to perhaps
low 60s. Modestly steepened mid-level lapse rates overspreading the
warm sector through the day, in tandem with diurnal heating, should
support around 500-1500 J/kg of MLCAPE by mid afternoon. A belt of
enhanced (50-60 kt) mid-level flow attendant to the upper trough
will move over parts of the upper OH Valley, lower Great Lakes, and
western Mid-Atlantic this afternoon and evening. This strong flow
aloft will contribute to substantial deep-layer shear (around 35-50
kt) and organized severe convection.

Current expectations are for robust thunderstorms to develop along
the cold front in eastern OH/western NY and northwest PA around
20-22Z. This initial development may be supercellular given the
strong deep-layer shear, with an associated threat for severe hail
given favorable lapse rates aloft. A brief tornado or two may also
occur. But, a fairly quick transition to a line is anticipated given
the linear forcing of the cold front. As this occurs, the threat for
scattered damaging winds should quickly increase as convection moves east-southeastward from eastern OH across western NY/PA and into
WV/western MD. Given the fairly narrow warm sector, this activity
should weaken by mid evening with the loss of daytime heating, and
as it encounters a much less unstable airmass in the central
Appalachians.

..Gleason/Dean.. 10/06/2024

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ACUS01 KWNS 071236
SWODY1
SPC AC 071234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Mon Oct 07 2024

Valid 071300Z - 081200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms appear unlikely today and tonight.

...Synopsis and Discussion...
Greatest thunderstorm potential today should exist across south FL
and the Keys, along and south of a ill-defined front draped across
the FL Peninsula. A weak surface low is present over the eastern
Gulf of Mexico this morning, and it is forecast to redevelop off the
southeast FL Coast by this evening. Some modest enhancement to the
low-level flow should occur through the day over south FL and
vicinity, but poor lapse rates should hinder robust updrafts even as
daytime heating occurs. While occasional strong/gusty winds appear
possible with any convection that can develop in this regime, the
overall severe threat appears too limited to include any
probabilities at this time.

Otherwise, thunderstorms will continue moving eastward across parts
of southern New England this morning ahead of a front, with
additional isolated development possible later this afternoon across
parts of the Carolinas. Occasional lightning flashes may also be
noted across parts of the Great Lakes, with low-topped convection
possible beneath cold mid-level temperatures associated with an
upper trough over eastern Canada. Finally, isolated high-based
thunderstorms may develop along parts of the Sierra into NV this
afternoon as a weak shortwave trough moves eastward.

..Gleason/Dean.. 10/07/2024

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ACUS01 KWNS 081232
SWODY1
SPC AC 081230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Tue Oct 08 2024

Valid 081300Z - 091200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/SOUTH FLORIDA AND THE KEYS...

...SUMMARY...
An isolated tornado threat associated with Hurricane Milton may
develop late tonight into early Wednesday morning across parts of
the central/southern Florida Peninsula and the Keys.

...Florida...
Ongoing thunderstorm activity this morning over south FL and
vicinity along/near a weak baroclinic zone should generally remain
sub-severe through the day, with modest low/mid-level flow limiting
deep-layer shear. The latest NHC forecast shows Hurricane Milton
moving into the southeastern Gulf of Mexico late tonight into early
Wednesday morning. Milton's wind field is also forecast to expand
through the period, with enhanced low-level southerlies expected to
gradually overspread parts of the Keys and south FL late tonight
(mainly after 06Z). A corresponding slow increase in low-level shear
is anticipated in this time frame, which should support some
potential for updraft rotation and isolated tornado/waterspout
threat with any cells in outer rain bands on the eastern periphery
of Milton's center. Still, there is a fair amount of guidance which
shows that any outer rain bands that do manage to form late tonight
into early Wednesday morning may tend to remain offshore from the
Keys and southwest FL Coast. Even with this uncertainty, some threat
for a couple of brief tornadoes may exist across these areas, mainly
in the 06-12Z time frame. The threat for a few tornadoes is expected
to increase into the Day 2/Wednesday time frame (after 12Z/8 AM EDT
Wednesday morning) across a greater portion of central/south FL and
the Keys as Milton approaches the FL Gulf Coast.

..Gleason/Jewell.. 10/08/2024

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ACUS01 KWNS 101224
SWODY1
SPC AC 101222

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0722 AM CDT Thu Oct 10 2024

Valid 101300Z - 111200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...Synopsis and Discussion...
With Milton having moved east and off the FL Atlantic Coast,
thunderstorms are not expected over FL through the rest of the
period. Otherwise, isolated convection that may produce occasional
lighting appears possible across parts of the southern Plains and
southeast AZ/southern NM. The activity over the southern Plains will
largely be tied to modest low-level warm advection and weak ascent
associated with a shortwave trough moving southward from NE/KS.
Instability is forecast to remain weak, and severe thunderstorms are
not expected.

..Gleason/Jewell.. 10/10/2024

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ACUS01 KWNS 111245
SWODY1
SPC AC 111244

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Fri Oct 11 2024

Valid 111300Z - 121200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorm potential will remain low today.

...Synopsis and Discussion...
Isolated showers and thunderstorms producing occasional lighting may
persist for a few more hours across eastern/southern OK and vicinity
before diminishing as modest warm advection with a
south-southwesterly low-level jet weakens later this morning.

A cold front will advance southeastward across the Upper Midwest and
Great Lakes through the period. While low-level moisture and related instability are expected to remain quite limited ahead of the front,
cool mid-level temperatures and strong ascent with the upper trough
may support isolated thunderstorms across parts of northern MI this
afternoon and evening. Some of this activity could produce
occasional gusty winds given strengthening low/mid-level flow
through the day, but the overall severe threat still appears low.
The front and upper trough will continue across the Northeast
tonight. But, instability is forecast to remain minimal, which
should hinder thunderstorm potential.

Convection should also develop this afternoon across parts of south
FL and the Keys. Even with poor mid-level lapse rates and warm
temperatures aloft, some of this activity could produce isolated
lightning flashes.

A shortwave trough will move across the northern CA/western OR
vicinity this evening and overnight. Thunderstorms may occur
offshore, but potential for lightning over land appears limited.

..Gleason/Jewell.. 10/11/2024

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ACUS01 KWNS 121236
SWODY1
SPC AC 121234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Sat Oct 12 2024

Valid 121300Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms appear unlikely today and tonight.

...Synopsis and Discussion...
Within broad upper troughing over central/eastern Canada, an
embedded mid-level perturbation will gradually amplify as it moves southeastward over the Upper Midwest and Great Lakes through the
period. At the surface, a weak low will gradually develop eastward
across the Midwest and eventually reach the northwest OH vicinity by
late tonight. An associated cold front will continue moving
southward across the central Plains and upper/mid MS Valley, while a
warm front extending eastward from the surface low remains across
northern IL/IN/OH through this evening.

Limited low-level moisture and weak large-scale forcing across the
warm sector suggest that surface-based thunderstorm potential should
remain low today across the Great Lakes/OH Valley region. However,
most guidance does show some elevated convection developing by late afternoon/early evening across southern Lower MI and vicinity.
00/06Z NAM runs show much more instability present compared to most
other guidance, with a general consensus that around 500 J/kg of
MUCAPE may exist when convection initiates.

Even with strong shear in the cloud-bearing layer, the weak
instability forecast should tend to limit the threat for severe hail
with any thunderstorms that can form over Lower MI and subsequently
spread east-southeastward across northern IN/OH this evening and
overnight. Still, small hail may occur with the more robust cores.
Occasional gusty winds may also be able to reach the surface given
the forecast strength of the low/mid-level flow, presence of a
somewhat dry sub-cloud layer/weak DCAPE, and relatively shallow
near-surface stable layer.

..Gleason/Jewell.. 10/12/2024

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ACUS01 KWNS 131247
SWODY1
SPC AC 131246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sun Oct 13 2024

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL/SOUTHERN APPALACHIANS AND TENNESSEE VALLEY...

...SUMMARY...
Strong to locally severe thunderstorms are possible, mainly this
evening, across parts of the central/southern Appalachians and
Tennessee Valley. Isolated wind damage and marginally severe hail
should be the main threats.

...Central/Southern Appalachians into the Tennessee Valley...
Ongoing elevated thunderstorms across northeast OH and western PA
should continue eastward this morning in tandem with an enhanced west-southwesterly low-level jet. This activity is expected to
outpace low-level moisture return and related destabilization today,
and eventually weaken. But in the short term, small hail remains
possible. Meanwhile, a vigorous shortwave trough over the Upper
Midwest will dig southeastward through the base of a large-scale
mid/upper trough, and yield amplification of this trough southward
across the Great Lakes through Monday morning. Ascent preceding this
shortwave trough will overspread parts of the central/southern
Appalachians into the TN Valley, mainly during the evening and
overnight.

A leading and weaker mid-level perturbation will encourage the
primary surface low to develop eastward across PA this afternoon
through early evening. A surface cold front will extend southwest of
this low into the TN Valley. Convective development along the front
appears likely to be delayed until early evening, as the
strengthening large-scale ascent aids in increasing low-level
convergence along the front amid generally veered flow within the
warm sector. Surface dew points should largely range from the mid
50s in WV to a narrow corridor of low 60s in TN, yielding a plume of
MLCAPE around 500-1500 J/kg amid initially steep mid-level lapse
rates.

Recent guidance still differs regarding storm coverage along/ahead
of the cold front this evening, from almost none to scattered. This
is perhaps in response to the ascent with the shortwave trough
strengthening after peak diurnal heating. The strongest 700 mb
westerlies (around 40-55 kt) should be confined to mainly northeast
of the TN Valley. Forecast hodographs above this level appear small,
owing to weakening winds with height as fast mid/upper flow lags to
the north-northwest. This suggests supercell structures may struggle
to develop/be sustained. But the strong 700 mb flow could support
localized damaging winds in any multicell clusters that can form.
Farther southwest, somewhat greater buoyancy could foster small to
marginally severe hail as well. The overall severe threat appears
likely to remain rather isolated, and no changes have been made to
the Marginal Risk with this update.

..Gleason/Jewell.. 10/13/2024

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ACUS01 KWNS 141233
SWODY1
SPC AC 141232

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0732 AM CDT Mon Oct 14 2024

Valid 141300Z - 151200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...Synopsis and Discussion...
Isolated thunderstorms will remain possible this morning and
afternoon across parts of New England as an upper trough continues
eastward. Other low-topped convection will be possible today beneath
the upper trough over portions of the Great Lakes, with seasonably
warm lake temperatures and cold mid-level temperatures supporting
modest buoyancy and occasional lightning flashes. Finally, isolated thunderstorms may occur this afternoon and evening across parts of
UT and northern AZ into western CO, as a weak shortwave trough moves
slowly southeastward over the Great Basin and Southwest. Weak
instability across all these regions should greatly limit potential
for severe thunderstorms through the period.

..Gleason/Jewell.. 10/14/2024

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ACUS01 KWNS 151242
SWODY1
SPC AC 151241

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 AM CDT Tue Oct 15 2024

Valid 151300Z - 161200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
A highly amplified mid/upper-level pattern will persist over the
CONUS, characterized by an elongated cyclone over the Great Lakes
and Northeast, with a primary center initially over the lower St.
Lawrence River region. The associated 500-mb low should drift
erratically near its present location for most of today, then move northeastward toward the easternmost extension of QC overnight. A
strong, basal trough was evident in moisture-channel imagery over
the Lower Great Lakes and southern Upper Great Lakes region,
westward across the upper Mississippi Valley. This trough will
pivot southeastward through the period, then by 12Z tomorrow, extend
from offshore of New England across VA, the western Carolinas,
northern GA, to central MS and the Arklatex region. Associated cold
air aloft, steep low/middle-level lapse rates (aided by
boundary-layer flow off the relatively warm lakes) and weak moisture
will foster isolated thunderstorm potential south of portions of
Lakes Erie and Michigan today.

Elsewhere, thunderstorms have persisted all night in a residual, quasistationary, convectively reinforced baroclinic zone draped
across the Bahamas and southern/western Straits of FL. This thunder
potential should persist episodically through the period, with some
inland development possible this afternoon across the Everglades and
perhaps adjoining southern parts of metro South FL. A stronger
boundary, moving southward through northern/central FL as a cold
front, may support isolated thunder near that part of the FL East
Coast today, amid modest moisture/lift. In the Four Corners region,
isolated to widely scattered, high-based thunderstorms are expected
this afternoon as heating/mixing reduce generally 30s F surface
dewpoints into the 20s, but still just enough moisture to support
weak (generally less than 200 J/kg) peak MLCAPE.

..Edwards.. 10/15/2024

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ACUS01 KWNS 161214
SWODY1
SPC AC 161213

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0713 AM CDT Wed Oct 16 2024

Valid 161300Z - 171200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not currently expected on Wednesday.

...Synopsis/Discussion...
In mid/upper levels, a highly amplified, yet still quite progressive
pattern will persist through the period over the CONUS. A leading
synoptic trough was initially positioned from a low near Anticosti
Island in the Gulf of St. Lawrence, southwestward across New
England, the near-coastal Mid-Atlantic region, and the southern
Appalachians, to parts of AR and eastern OK. The southern
Appalachian part of the trough is expected to consolidate into a
closed cyclone as it moves eastward across the Carolinas and VA,
with a well-defined 500-mb low expected over the Outer Banks
vicinity by 12Z tomorrow. However, associated surface frontal-wave cyclogenesis and related elevated thunder potential in the wrapping
conveyor both should remain offshore. The trailing cold front --
analyzed at 11Z from central FL across the north-central Gulf to
near CRP and across south-central TX -- will support isolated
thunderstorm potential today over parts of south FL and deep south
TX before moving south of both areas.

Meanwhile, a synoptic-scale trough -- with several embedded small shortwaves/vorticity lobes -- is apparent in moisture-channel
imagery from the AK Panhandle south-southeastward, just offshore of
and parallel to the CONUS Pacific Coast. As these features move
ashore today, preceded by several other vorticity lobes, height
falls and colder air aloft will spread inland, steepening midlevel
lapse rates atop marginal low/middle-level moisture over parts of
the Pacific Northwest and a broad area of the Intermountain West/
Great Basin, with low-level warm advection and diabatic heating also
aiding instability in the interior swath. Isolated thunderstorms
should result.

..Edwards/Goss.. 10/16/2024

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ACUS01 KWNS 171233
SWODY1
SPC AC 171231

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0731 AM CDT Thu Oct 17 2024

Valid 171300Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not expected through tonight.

...Synopsis...
In mid/upper levels, a highly amplified yet progressive pattern will
persist through the period, as a strong, synoptic-scale ridge shifts
eastward over the Great Lakes, and the Mississippi/Ohio/Tennessee
Valleys. Upstream, a strong trough now near the coastal Pacific
Northwest will dig southeastward across interior parts of the West
Coast States today into this evening, and much of the western Great Basin/Intermountain regions overnight. By 12Z, a 500-mb low should
form over eastern NV, along a trough extending from the northern
Rockies to the lower Colorado River Valley. As that occurs, a
weaker, shortwave trough -- evident in moisture-channel imagery near
the NV/UT and CA/AZ borders, should eject northeastward over the
central Rockies and central/northern High Plains, while weakening.
By the end of the period, broadly cyclonic flow will cover most of
the western CONUS.

Ahead of the strengthening main (Pacific Northwest) trough, height
falls and areas of DCVA/cooling aloft are forecast. Those will
overlie a southeastward-surging low-level cold front across the
Intermountain region, and support isolated to widely scattered
thunderstorm potential over a vast swath of the West, either side of
the front. Meager but sufficient low/midlevel moisture -- mostly
with distant/indirect origins in the subtropical gulfs either side
of northern Mexico -- will support this convection. Strong gusts
may accompany some of the afternoon and early evening activity
along/ahead of the cold front across northern parts of NV/UT, amidst strengthening deep shear. However, overall moisture/buoyancy appear
too meager to outline an unconditional severe area at this time.

..Edwards/Goss.. 10/17/2024

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