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DAY1SVR: Day 1 Convective
From
Mike Powell@618:250/1 to
All on Wed Aug 6 09:19:14 2025
ACUS01 KWNS 061240
SWODY1
SPC AC 061238
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Wed Aug 06 2025
Valid 061300Z - 071200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS TO THE MID-MISSISSIPPI VALLEY. AND PART
OF NORTHERN MINNESOTA...
...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the northern/central Plains to the Mid-Mississippi Valley, and over
part of northern Minnesota today and tonight.
...Northern/Central Plains into the Mid MS Valley...
An MCS continues to push southward across the Mid MO Valley this
morning. The current motion, particularly the westward backbuilding
of storms into more of east-central NE, have oriented this system
favorably to a moist low-level jet, which should support maintenance
of this line for the next few hours. Echo tops within this system
remain fairly cool and occasionally strong updrafts have persisted
for the last several hours. Additionally, a notable rise/fall
pressure couplet exists with this system, as sampled by the +4 mb
pressure rise as SUX. These factors indicate the MCS remains mature
and could still occasionally produce damaging gusts over the next
few hours across southeast NE, southwest IA, northwest MO, and far
northeast KS. This MCS should begin to weaken later this morning
when the low-level jet weakens.
The region will be within the mostly zonal flow between the upper
ridging centered over NM and a shortwave trough moving through SK
and MB. Some rising heights are possible during the second half of
the period as the pattern amplifies ahead of a shortwave trough
moving into the northern Rockies. A belt of stronger mid-level flow
(i.e. around 40 kt at 500 mb) will extend across the region, and
diurnal heating of the moist airmass in place will foster moderate
to strong buoyancy. The resulting combination of buoyancy and shear
would favor strong to severe thunderstorms, but the satellite
imagery lacks any notable disturbances upstream and the large-scale
ascent is nebulous. The surface pattern also lacks any well-defined
features, with only weak troughing sampled from the central Dakotas
to a weak low over northeast CO.
As such, when and where convective initiation occurs, if it occurs
at all, is uncertain. Convective initiation appears most likely near
the Black Hills into western NE within southeasterly low-level
upslope flow within a very moist/unstable airmass. Environmental
conditions support supercells with a conditional risk for large hail
and damaging winds. However, given the uncertainty regarding
coverage, will maintain Marginal risk (level 1 of 5).
...Northern MN...
A few storms may develop along the southern periphery of the
Canadian Prairies shortwave upper trough and surface low. Lapse
rates will be weaker across this area and the favorable
thermodynamic environment will be narrow. Any stronger storms will
likely remain close to the international border, but could produce
locally strong gusts or marginal hail.
..Mosier/Bentley.. 08/06/2025
$$
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From
Mike Powell@618:250/1 to
All on Mon Aug 11 08:34:50 2025
ACUS01 KWNS 111248
SWODY1
SPC AC 111246
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Mon Aug 11 2025
Valid 111300Z - 121200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...AND OVER PORTIONS OF NORTH DAKOTA INTO
NORTHERN MINNESOTA...
...SUMMARY...
Isolated strong to severe thunderstorms may pose some risk for
severe winds and hail across parts of the southern Plains, and
separately from North Dakota into northern Minnesota, mainly this
afternoon and evening.
...Southern Plains...
Convection has generally weakened this morning across eastern KS,
with a outflow reinforced front advancing southward across the
southern High Plains. This boundary is forecast to stall through the
morning and early afternoon, and it will likely serve as a focus for
renewed thunderstorm development later today. The southern extent of
upper troughing that exists over much of the Plains is forecast to
advance eastward across the southern High Plains this afternoon.
Initial development over the higher terrain of north-central into
northeast NM should occur in a modest low-level upslope flow regime,
with steep lapse rates aloft contributing to moderate instability.
Weak low-level winds will gradually veer to west-northwesterly and
modestly strengthen with height through mid/upper levels, supporting
modest deep-layer shear and some updraft organization.
Isolated severe hail may occur with initially more cellular
development across the southern High Plains, before some clustering
potentially occurs late this afternoon/evening farther east into the
TX Panhandle and northwest TX with more of a wind threat. While
deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered
thunderstorms developing with moderate to locally strong instability
amid ample daytime heating. Isolated damaging winds via strong
downbursts and marginally severe hail appear possible with the
stronger cores given seasonably cool temperatures aloft (around -10C
at 500 mb with the 12Z OUN observed sounding), and the Marginal Risk
has been expanded eastward for this possibility.
...North Dakota into Northern Minnesota...
Within upper troughing already established over the northern/central
Plains and central Canada, a mid-level shortwave trough and related
surface cold front are forecast to move east-southeastward over ND
and northern MN through the period. Modest low-level moisture
characterized by mid 50s to perhaps low 60s surface dewpoints should
be present ahead of the front across these areas. Diurnal heating
and modestly steepened lapse rates aloft should aid in the
development of weak instability this afternoon. Thunderstorms should
gradually increase in coverage along/ahead of the front this
afternoon/evening as they spread eastward over parts of ND into
northern MN. The stronger cells may produce marginally severe hail,
with sufficient deep-layer shear present for some convective
organization. With time, some clustering/upscale growth along the
front appears probable, with isolated strong to severe gusts
possible. The lack of stronger instability should tend to temper the
overall severe threat.
...Missouri/Iowa...
An MCV generated by overnight/early morning convection across the southern/central Plains should develop northeastward into parts of
northern MO and IA by this afternoon. It remains unclear whether
sufficient instability to support robust thunderstorms will be able
to develop today ahead of this feature given ongoing convection and
cloud debris. Regardless, some enhancement to the low/mid-level flow
and related deep-layer shear could support updraft organization if surface-based thunderstorms can develop. Given the continued
uncertainty regarding this potential, have held off on inclusion of
low severe probabilities across this region with this update.
..Gleason/Leitman.. 08/11/2025
$$
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From
Mike Powell@618:250/1 to
All on Tue Aug 12 08:47:30 2025
ACUS01 KWNS 121150
SWODY1
SPC AC 121148
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0648 AM CDT Tue Aug 12 2025
Valid 121300Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER GREAT LAKES/MIDWEST...AND PORTIONS OF THE SOUTHWEST...
...SUMMARY...
Strong to occasionally severe thunderstorms may impact parts of the
upper Great Lakes/Midwest today with both damaging winds and hail
possible. Gusty winds may also occur over southeast Arizona and
southwest New Mexico.
...Great Lakes/Midwest...
A band of thunderstorms associated with an MCV tracked northeastward
across parts of IA into northern IL and southern WI early this
morning while remaining mostly sub-severe. Still, there may be some
potential for strong to locally damaging winds with this activity as
it continues northeastward across Lake Michigan into parts of Lower
MI this morning/early afternoon as daytime heating gradually
destabilizes the boundary layer. Otherwise, additional convection
should develop later this afternoon along/ahead of a weak front over
parts of WI and the U.P. of MI as the southern portion of a
mid/upper-level trough moves eastward over the Upper Midwest/Great
Lakes. Instability is forecast to remain fairly modest ahead of the
front, but enough deep-layer shear should exist to support some
organized convection. Initial cells may be capable of producing
marginally severe hail, before clustering potentially increases the
threat for occasional strong to damaging winds.
A separate area of thunderstorms is forecast to develop this
afternoon farther south and ahead of the front from portions of the
Midwest into Lower MI. While this region will have relatively weaker
mid-level westerly flow and related deep-layer shear compared to
locations farther north, greater low-level moisture and instability
are expected to be present. As low-level lapse rates become
steepened with diurnal heating of the moist airmass, loosely
organized clusters may become capable of producing isolated damaging
winds as they spread generally east-northeastward through the
afternoon and early evening.
...Southwest...
Strong daytime heating should encourage diurnally driven convection
over the higher terrain of southeast AZ and southwest NM this
afternoon. With weak flow aloft and negligible shear, thunderstorms
should drift slowly southward. Still, occasional gusty winds may
occur with the more robust convection given steepened lapse rates.
..Gleason/Leitman.. 08/12/2025
$$
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From
Mike Powell@618:250/1 to
All on Sun Aug 17 10:11:07 2025
ACUS01 KWNS 171221
SWODY1
SPC AC 171220
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0720 AM CDT Sun Aug 17 2025
Valid 171300Z - 181200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...UPPER MIDWEST...MID ATLANTIC...AND SOUTHERN
NEW ENGLAND....
...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.
...Northern Plains into Upper Midwest...
A broad upper ridge remains in place over southern/central U.S
today. Several weak perturbations will top the ridge during this
forecast period, affecting much of the northern Plains and upper
Midwest. Each of these smaller-scale shortwave troughs will
potentially be associated with a cluster of thunderstorms.
Sufficient low-level moisture and 25-35 knots of westerly flow aloft
pose some conditional risk of severe storms throughout this region,
but considerable uncertainty on the timing and placement of
convection precludes upgrading any areas to SLGT at this time.
Multiple areas of ongoing convection this morning further complicate
the forecast. Perhaps by 1630z, areas of stronger daytime heating/destabilization will allow better focus of the severe
outlook.
...Mid Atlantic into southern New England...
A cold front currently extends from OH northeastward into the St.
Lawrence Valley. Forecast soundings ahead of the front show weak
mid-level lapse rates and limited mid-level dry air. However,
strong heating into the 80s and 90s F, coupled with dewpoints near
70F will yield MLCAPE around 1000 J/kg. Sufficient westerly flow
aloft and frontal forcing may be sufficient for isolated strong
storms capable of locally gusty/damaging winds this afternoon.
..Hart/Dean.. 08/17/2025
$$
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From
Mike Powell@618:250/1 to
All on Tue Aug 19 09:03:10 2025
ACUS01 KWNS 191255
SWODY1
SPC AC 191253
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Tue Aug 19 2025
Valid 191300Z - 201200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN ROCKIES...
...SUMMARY...
Scattered strong to severe thunderstorms capable of damaging winds
will be possible across the south-central Great Plains and Ozarks to
the Ohio Valley this afternoon and evening. Isolated severe
thunderstorms may also occur across parts of the northern Rockies
including western and northern Montana.
...South-central Plains and Ozarks to Ohio Valley...
Outside of a few areas of lingering early day convection/small-scale
outflows, a hot air mass and relatively high moisture content will
reside to the south of a synoptic front extending from the
south-central Plains to the Midwest/Ohio Valley. Moderate to strong
buoyancy with daytime heating, beneath a residual plume of
relatively steep lower/mid-tropospheric lapse rates, will exist
particularly across parts of the south-central Plains to Ozark
Plateau, including parts of Kansas/Oklahoma to Arkansas/southern
Missouri. As storms diurnally develop/increase, upscale-growing
thunderstorm development should occur during the mid to late
afternoon and early evening. While weak deep-layer winds and shear
are likely to limit the risk for organized severe convection,
thermodynamic profiles will be conducive for downbursts and
severe-caliber wind gusts with the stronger storms, particularly
this afternoon through around sunset.
...Northern Rockies including western/northern Montana...
The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late
this afternoon, and more so into this evening, across parts of
northern Idaho in western and eventually northern Montana.
Sufficient moisture/buoyancy near and behind a surface front, along
with strengthening flow aloft, will support the possibility of some
severe storms, and potentially some clustering/organization to the
storms as they progress across western/northern Montana.
West-southwesterly mean flow strengthening to 30-40+ kt in the
cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will
likely be sufficient for downward mixing of momentum to contribute
to a few strong to severe wind gusts.
..Guyer/Dean.. 08/19/2025
$$
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From
Mike Powell@618:250/1 to
All on Wed Aug 20 08:36:07 2025
ACUS01 KWNS 201231
SWODY1
SPC AC 201230
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Wed Aug 20 2025
Valid 201300Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS/DEEP SOUTH AND NORTHERN PLAINS...
...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Gulf Coast states may pose a risk for localized damaging
wind gusts this afternoon and evening. Isolated severe thunderstorms
may also occur across eastern Montana and northern North Dakota.
...Texas to Lower Mississippi Valley/Gulf Coast States...
A convectively augmented effective front will continue to progress
southward, southward-shifting the potential for microburst-related
wind damage regionally. Diurnal heating of a moist boundary layer
will result in a moderately to strongly unstable and weakly capped
airmass by afternoon, with the strongest buoyancy (2500+ J/kg
MLCAPE) expected across central/east Texas east-northeastward to Mississippi/western Alabama/southern Tennessee. Some small-scale
clusters may evolve, but weak vertical shear will otherwise tend to
keep the overall pulse-type damaging wind potential very isolated.
...Northern Plains...
The region will be influenced by late-day/nighttime height falls as
a shortwave trough emerges eastward from the Canadian Rockies, with
an eastward-advancing cold front moving across eastern Montana into
North Dakota tonight. A narrow corridor of moderate to large
buoyancy is expected along/ahead of the surface cold front, and near
a pre-frontal surface trough. Beneath a plume of warm elevated
mixed-layer air, mid/upper-level support for the initiation of
boundary-layer based thunderstorm development is forecast to
generally remain north of the international border.
One exception may be in the post-frontal environment across eastern
Montana, the environment would be conducive to a few severe storms
capable of hail/wind. While the risk for severe thunderstorms
appears largely conditional into North Dakota where stronger
destabilization is expected, isolated deeper convective development
is plausible across northwestern North Dakota in proximity to the
surface low/front late this afternoon, and more so this evening.
Should this occur, forecast soundings indicate the environment would
support isolated supercell development and related severe-weather risks.
..Guyer/Marsh.. 08/20/2025
$$
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From
Mike Powell@618:250/1 to
All on Thu Aug 21 08:27:29 2025
ACUS01 KWNS 211253
SWODY1
SPC AC 211251
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Thu Aug 21 2025
Valid 211300Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST AND SOUTHERN ARIZONA...
...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
northern Plains and Upper Midwest this afternoon and evening, with
severe wind gusts and hail the primary concerns. A few strong to
severe storms could also occur across southern Arizona.
...Northern Plains/Minnesota...
Late-day height falls are expected regionally in relation to an
amplifying shortwave trough over the Canadian prairies. While the
primary large-scale forcing will be north of the international
border, high-level diffluent flow is expected across the eastern Dakotas/Minnesota, coincident with the front that will be draped
across the region at peak heating. Short-term models (HRRR/RRFS) are
tending to limit late-afternoon/evening convective development,
while most global models and most HREF constituents are a bit more
aggressive, which is plausible and lends credence to the potential
for at isolated severe storms within a moderately to strongly
unstable environment near the front. Deep-layer should be sufficient
to potentially yield a few supercells. Increasing storm coverage
later into the evening/overnight will be supported by an increasing
low-level jet.
...North-central High Plains including eastern Wyoming...
Northeasterly low-level upslope flow evolving within the
post-frontal environment, and differential heating in vicinity of
higher terrain, are expected to influence widely scattered
thunderstorm development by late afternoon, particularly across
eastern Wyoming. While forecast buoyancy is not expected to be
particularly strong, adequate deep-layer shear will prove supportive
of organized updrafts that could generate hail/wind, including the
possibility that a couple of eastward-moving clusters could evolve
by early evening.
...Southern Arizona...
The upper ridge should shift slightly northward regionally, with a
modest enhancement to mid-level easterly flow late today
particularly across southeast Arizona. With isolated storm
development expected initially over the rim/mountains this
afternoon, storms should drift west-southwestward into a moist/very
hot boundary layer, with the potential for outflows/blowing dust to
reach the desert floor.
..Guyer/Marsh.. 08/21/2025
$$
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From
Mike Powell@618:250/1 to
All on Fri Aug 22 10:01:17 2025
ACUS01 KWNS 221251
SWODY1
SPC AC 221250
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Fri Aug 22 2025
Valid 221300Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS TO THE UPPER MIDWEST AS WELL AS ARIZONA...
...SUMMARY...
Strong to locally severe thunderstorms are possible from parts of
the central and northern High Plains to the Upper Midwest, and
across parts of Arizona.
...Upper Midwest/Upper Great Lakes...
Upper trough amplification will continue to occur over
Manitoba/northern Ontario through tonight, with consequential height
falls over the upper Great Lakes. A cold front will continue to
advance southeastward regionally, with a semi-moist air mass
preceding it. A consequential factor for portions of the region will
be an MCS centered across far eastern South Dakota early this
morning, which will continue to disturb the frontal zone and nearby
warm sector for the first part of the day. This may especially be
the case across southern Minnesota and vicinity.
But on the periphery of the MCS-influenced corridor, potential
severe storm development could occur by late afternoon, perhaps most
likely across eastern Nebraska and western Iowa, but also across
northwest Wisconsin/Upper Michigan where vertical shear will be
stronger but with more modest buoyancy. Hail and damaging winds
would be possible in both scenarios, but likely on a relatively
isolated basis.
...Wyoming/Colorado and central High Plains...
A subtle ridge-peripheral disturbance noted in water vapor imagery,
along with strong surface heating, should aid thunderstorm
development initially across Wyoming/Colorado. This activity should
propagate east-southeast toward lower elevations in the presence of
moist low-level upslope flow. Hail and wind are possible with this
activity, especially within a corridor across interior/southeast
Wyoming into northeast/east-central Colorado.
...Arizona...
The upper high will shift west-northwestward through tonight,
maintaining and potentially strengthening easterly mid-level winds
across southern Arizona, in addition to the possibility of slightly
cooler (degree or two C) mid-level temperatures. Lingering morning
cloud cover should gradually abate into the afternoon, with a very hot/residually moist boundary layer contributing to widely scattered thunderstorm development, initially over higher terrain.
West/southwestward spreading storms will pose the potential for
strong wind gusts/blowing dust onto the desert floor.
..Guyer/Kerr.. 08/22/2025
$$
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From
Mike Powell@618:250/1 to
All on Fri Aug 22 13:07:24 2025
ACUS01 KWNS 221632
SWODY1
SPC AC 221630
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Fri Aug 22 2025
Valid 221630Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE NORTHERN/CENTRAL HIGH PLAINS TO THE UPPER MIDWEST/GREAT
LAKES...AND PORTIONS OF SOUTHERN/CENTRAL ARIZONA...
...SUMMARY...
Strong to locally severe thunderstorms may occur today from parts of
the northern and central High Plains to the Upper Midwest/Great
Lakes, and separately across parts of Arizona. Damaging winds and
occasional hail should be the main threats.
...Synopsis...
A mid/upper-level trough/low centered over Manitoba late this
morning will move east-southeastward across Ontario and the Upper
Midwest/Great Lakes through the period. At the surface, a weak cold
front is forecast to develop southeastward across the
northern/central High Plains and Upper Midwest this afternoon and
evening. This boundary should serve as a focus for additional
thunderstorm development later today, some of which could become
strong to severe. A mid/upper-level anticyclone will remain anchored
over the Four Corners region today, with modest easterly mid-level
flow persisting over parts of AZ.
...Northern/Central High Plains to the Upper Midwest/Great Lakes...
A broad zone of isolated strong to severe thunderstorm potential
remains evident today, generally along/near a convectively
reinforced cold front extending from the central High Plains
east-northeastward to the Upper Midwest/Great Lakes. Within this
broad zone, three somewhat separate regimes of severe potential are apparent.
Thunderstorms have recently developed across parts of
central/eastern MN and far northwest WI ahead of a remnant
MCV/subtle mid-level shortwave trough. The airmass downstream from
this activity across northern WI into the U.P. of MI is only weakly
unstable, with scattered to broken mid/upper-level clouds present.
Stronger mid-level flow is also forecast to generally lag behind the
surface cold front across this region. Still, a small cluster or two
may eventually evolve from the ongoing convection in MN, and spread
eastward through the afternoon/early evening. Occasional damaging
winds should be the main threat, but some hail may also occur with
the stronger cores given cool mid-level temperatures and around
25-35 kt of deep-layer shear aiding updraft organization. Considered
adding a Slight Risk for severe/damaging winds across parts of
northern WI and vicinity, but confidence in more robust
destabilization occurring remains low. Trends will be monitored for
a possible upgrade at 20Z, if needed.
Outflow from earlier thunderstorms continues to advance southward
across parts of eastern NE and northwest IA per recent surface
observations and visible satellite imagery. The effect of this
outflow surge on additional thunderstorm development this afternoon
remains unclear, as the primary cold front lags the outflow by a
considerable extent. Some guidance suggests that a couple of
supercells or perhaps a small cluster may develop over far southeast
SD into eastern NE and western IA later today as the airmass across
these areas gradually destabilizes. At least an isolated risk for
severe hail and damaging winds will exist if this occurs. But, the
overall severe threat remains too uncertain for a categorical
upgrade with this outlook update.
Farther west, a subtle mid-level ridge-peripheral disturbance noted
in water vapor imagery across southern WY and northwest CO, along
with strong daytime heating, should aid thunderstorm development
initially across the higher terrain of the central Rockies later
this afternoon. This activity should propagate east-southeastward
toward lower elevations in the presence of moist, post-frontal
low-level upslope flow. Isolated severe hail and winds are possible
with this activity, especially within a corridor across
interior/southeast WY into northeast/east-central CO.
...Arizona...
A fair amount of convective cloud debris is present today across
parts of AZ per recent visible satellite imagery. This may tend to
delay diurnal heating and related steepening of low-level lapse
rates to some extent. But, eventual airmass recovery is still
expected by late afternoon/early evening, with seasonably moist
low-levels still noted on the 12Z observed PHX sounding.
Thunderstorms should once again form initially along the higher
terrain of the Mogollon Rim and southeastern AZ before spreading west-southwestward across the lower elevations of central/southern
AZ through the evening. Sufficient instability, a very well-mixed
boundary layer, and modest easterly mid-level flow should all
support an isolated threat for severe/damaging winds with this activity.
..Gleason/Moore.. 08/22/2025
$$
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From
Mike Powell@618:250/1 to
All on Sat Aug 23 09:04:58 2025
ACUS01 KWNS 231247
SWODY1
SPC AC 231246
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sat Aug 23 2025
Valid 231300Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FRONT RANGE/CENTRAL HIGH PLAINS...
...SUMMARY...
Isolated severe storms are possible near the Colorado/Wyoming Front
Range and central High Plains this afternoon and evening.
...Front Range/Central High Plains...
Multiple subtle upper ridge-peripheral impulses and a belt of
moderately strong northwesterly winds aloft will influence the
region as low-level upslope flow increases late today within the
post-frontal environment. At least widely scattered thunderstorm
development is expected initially over the mountains, with
subsequent intensification as storms develop east-southeastward into
a moderately unstable air mass, with buoyancy maximized
near/immediately east of the urban corridor/I-25. Steep mid-level
lapse rates and 40+ kt effective shear will support the possibility
of isolated supercells capable of large hail and some locally
stronger wind gusts through early evening.
...Midwest/Great Lakes...
A few showers and thunderstorms will likely develop along a cold
front as it moves across the Great Lakes/Midwest this afternoon.
Warm 700mb temperatures in the presence of only low 60s dewpoints
will limit overall buoyancy and updraft strength, likely keeping
severe-storm potential minimal.
..Guyer/Kerr.. 08/23/2025
$$
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From
Mike Powell@618:250/1 to
All on Sun Aug 24 09:20:52 2025
ACUS01 KWNS 241311
SWODY1
SPC AC 241310
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0810 AM CDT Sun Aug 24 2025
Valid 241300Z - 251200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND NORTHEAST...
...SUMMARY...
A few severe storms are expected this afternoon and evening across
the south-central High Plains spanning eastern Colorado into western
Oklahoma. Scattered strong to severe storms are also possible across
portions of Pennsylvania and New York.
...South-central High Plains..
Within an amplified upper flow regime, a moderately strong belt of northwesterly winds aloft will exist over the region, with one or
more low-amplitude ridge-peripheral disturbances expected to pivot
eastward later today over the central Rockies. A pronounced surface
anticyclone will settle into the northern Plains, forcing the
leading edge of more continental air into the southern Plains by the
end of the period. A corridor of low-level warm advection will
become established from southern Wyoming into western Oklahoma
coincident with the northwest/southeast-oriented front.
Widely scattered generally non-severe elevated storms will probably
persist this morning across western Kansas, with some potential that
the storms may help focus some renewed/increasing convective
potential later today from southwest Kansas into western
Oklahoma/eastern Texas Panhandle. Aided by increasing low-level
upslope flow, other potentially severe storms are expected to
develop across the Colorado Front Range vicinity by late afternoon
and drift southeastward through early/mid-evening. A couple of
supercells will initially be possible, before storms tend to cluster
by evening. Large hail and damaging winds are the primary concerns
regionally, although current thinking is that overall potential
should remain relatively isolated.
...Northeast including New York/Pennsylvania...
A prominent upper-level trough over Ontario/Quebec and Great Lakes
will shift eastward today. An associated surface front is forecast
to advance into western portions of New York/Pennsylvania by early
afternoon. Modest boundary-layer heating is expected to aid
destabilization ahead of the front and convective temperatures
should be breached by around 20-21z; although, deep-layer lapse
rates are not expected to be particularly steep (0-6 km values
around 6.5 C/km). These storms could generate locally strong winds,
and perhaps some hail, with the main risk from mid-afternoon into
early evening.
..Guyer/Kerr.. 08/24/2025
$$
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From
Mike Powell@618:250/1 to
All on Mon Aug 25 08:52:56 2025
ACUS01 KWNS 251240
SWODY1
SPC AC 251238
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Mon Aug 25 2025
Valid 251300Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
ARIZONA...
...SUMMARY...
Isolated severe wind gusts are possible over parts of south-central
Arizona this afternoon through early evening. Otherwise, the
potential for severe storms is low across the remainder of the
continental U.S.
..Synopsis...
A large upper-level trough will continue to amplify across the
eastern CONUS today. High pressure, currently analyzed across the
northern Plains early this morning will expand slowly southward
through the day which will push the polar front off the Atlantic
coast and perhaps into the Gulf. A persistent upper-level ridge will
exist across the Southwest and into the Great Basin/Rocky Mountains.
Beneath this ridge, a continued monsoon push will result in
widespread thunderstorm activity this afternoon/evening.
...Southern Arizona...
Thunderstorms are forecast to develop this afternoon/evening across
much of the Southwest amid weak to moderate instability (1000-1500
J/kg MLCAPE) as temperatures cool aloft. A belt of stronger
mid-level southeasterly flow (20-25 kt) is forecast to overspread
the region and provide ample shear for some multicell storm
clusters. Initial storms which are expected to form across the
higher terrain in southeast Arizona may result in congealing outflow
with a damaging wind threat as storms move generally
west-northwestward through the evening.
..Guyer/Kerr.. 08/25/2025
$$
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-
From
Mike Powell@618:250/1 to
All on Tue Aug 26 09:42:39 2025
ACUS01 KWNS 261249
SWODY1
SPC AC 261248
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Tue Aug 26 2025
Valid 261300Z - 271200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe storms are not expected across the continental U.S.
today.
...Synopsis...
An expansive upper-level trough will persist across the eastern
CONUS today, where a cool, dry airmass and high pressure
will be prevalent and limit thunderstorm potential aside from
Florida. Monsoon-related scattered thunderstorms will be common
across much of the non-coastal West.
...Southern Arizona/Lower Colorado River Valley...
A northward-moving mid-level impulse/MCV will spread from the Lower
Colorado River Valley/northern Arizona this morning into Utah,
allowing for subsequent clearing/heating across southern Arizona
toward the Lower Colorado River Valley. Thunderstorms will again
develop and increase this afternoon especially in vicinity of higher
terrain. A few instances of strong thunderstorm winds/wet
microbursts could occur regionally this afternoon into evening, but
the overall potential is expected to remain quite isolated and
marginal overall.
..Guyer/Kerr.. 08/26/2025
$$
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From
Mike Powell@618:250/1 to
All on Wed Aug 27 08:05:38 2025
ACUS01 KWNS 271254
SWODY1
SPC AC 271253
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Wed Aug 27 2025
Valid 271300Z - 281200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN COLORADO...
...SUMMARY...
Some strong to locally severe storms may occur across eastern
Colorado and the central High Plains late this afternoon and early evening.
...Eastern Colorado/Central High Plains...
Prevalent cloud cover and some lingering mostly light precipitation
should eventually abate later this afternoon, with thunderstorms
expected to develop/increase initially over the mountains by around mid-afternoon. These storms will spread east-southeastward toward
the instability axis across the adjacent High Plains through early
evening. Moderately strong mid-level flow could support some
semi-organized storms, and a couple of clusters could evolve by
evening. Localized instances of marginally severe hail and/or wind
could occur, although locally heavy rainfall may be more of a
prevalent concern.
...Upper Midwest...
A region of moderate instability is forecast to develop from eastern
South Dakota into southern Minnesota this afternoon. But this will
be in the wake of a southeastward-moving shortwave trough, with weak
height rises and subsidence in its wake. Nonetheless, isolated storm development may occur by late afternoon/early evening, and a few
strong storms are conceivable.
..Guyer/Kerr.. 08/27/2025
$$
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From
Mike Powell@618:250/1 to
All on Fri Aug 29 10:06:13 2025
ACUS01 KWNS 291254
SWODY1
SPC AC 291252
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Fri Aug 29 2025
Valid 291300Z - 301200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL/SOUTHERN HIGH PLAINS AND SABINE RIVER VALLEY...
...SUMMARY...
Thunderstorms capable of large hail and isolated severe wind gusts
will be possible mainly late this afternoon into evening across
parts of the southern and central High Plains. A few marginally
severe storms could also occur today over parts of the Sabine River Valley.
...Central/southern High Plains...
Multiple ridge-riding mid/upper-level disturbances will transition
generally east/eventually southeastward from the central Rockies and
northern High Plains today. Weak lee-side low development will occur
across southeast Colorado and also perhaps farther north across the
central High Plains, with modestly sharpening low-level convergence
in vicinity of the lee trough. This will lead to a gradual
enhancement of low-level upslope flow particularly across east-central/southeast Colorado and northeast New Mexico.
Storms should develop/increase by mid-afternoon and gradually move
eastward off the Colorado mountains/Raton Mesa vicinity, with other
development occurring near the surface boundary extending
north-northeastward into west-central Nebraska/southern South
Dakota. Surface dewpoints in the lower to mid 60s F will contribute
to an axis of moderate instability by peak heating. With moderately
strong northwesterly mid-level flow persisting regionally, 35-40 kt
or greater effective shear will exist from the Raton Mesa vicinity
across the central High Plains into west-central Nebraska. A few
supercells capable of large hail may occur, with the additional
possibility of wind damage, especially with a probable clustering of
storms across eastern Colorado/northeast New Mexico toward western
Kansas and the Oklahoma/Texas Panhandles.
...Sabine River Valley...
A relatively widespread corridor of showers/thunderstorms are
ongoing this morning across northeast Texas to central/southeast
Louisiana to the north of a front that will settle southward today
across the region. A related cloud canopy will extend southward into
the warm sector, but moderate destabilization should occur into the
afternoon south of the front and on the south/southwest flank of the
residual early day storms. Some stronger storms could persist and/or
develop near the front this afternoon, with isolated instances of
damaging winds a possibility as low-level lapse rates steepen.
..Guyer/Bentley.. 08/29/2025
$$
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From
Mike Powell@618:250/1 to
All on Sat Aug 30 08:49:52 2025
ACUS01 KWNS 301250
SWODY1
SPC AC 301248
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sat Aug 30 2025
Valid 301300Z - 311200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN HIGH PLAINS...
...SUMMARY...
Some strong to locally severe thunderstorms may occur late this
afternoon and evening across the southern High Plains.
...Southern High Plains...
A belt of moderate-strength west-northwesterly flow aloft will
persist atop a moist airmass regionally. Post-MCS air mass
influences and lingering cloud cover/outflows may be factors into
the afternoon, but RAP/HRRR-related guidance has trended a bit more
unstable and potentially more conducive to some isolated severe
storms later today. While confidence in forecast details are not
particularly high, this potential appears to be mainly focused in a
corridor across northeast New Mexico into the Texas Panhandle/Texas
South Plains, and possibly western Oklahoma later this afternoon
into evening. This is where locally moderate destabilization may
occur coincident with effective shear magnitudes that may reach
30-40 kt, with storm development focused near the surface trough
and/or influenced by differential heating. A few instances of severe
hail and/or wind will be possible.
..Guyer/Bentley.. 08/30/2025
$$
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From
Mike Powell@618:250/1 to
All on Sat Aug 30 13:58:12 2025
ACUS01 KWNS 301628
SWODY1
SPC AC 301626
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Sat Aug 30 2025
Valid 301630Z - 311200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF EASTERN NM...THE TX PANHANDLE...AND FAR WESTERN OK...
...SUMMARY...
Some strong to locally severe thunderstorms may occur late this
afternoon and evening across the southern High Plains.
...Synopsis and Discussion...
Recent surface analysis places a pair of highs across the CONUS, one
over southern Lower MI and another in the eastern ID/southwest MT
vicinity. A reservoir of low-level moisture, characterized by
dewpoints above 60 deg F, exists between these two features, from
the southern CONUS up through the Plains. The low-level moisture
will help foster thunderstorm development over much of this area,
with the highest coverage anticipated along the surface troughing
that extends from a pair of surface lows over the central Plains
into the southern High Plains.
A belt of moderate west-northwesterly flow aloft will extend
eastward from eastern CO/far northeast NM across KS into the Ozarks.
Southern periphery of this stronger flow will help support moderate
effective bulk shear across northeast NM and the TX Panhandle/TX
South Plains. Despite residual cloud cover and poor lapse rates,
ample low-level moisture will help support modest buoyancy across
the region as well. The resulting environmental conditions may
result in a few stronger storms capable of hail (likely below 1" in
diameter) and/or damaging gusts.
..Mosier/Dean.. 08/30/2025
$$
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From
Mike Powell@618:250/1 to
All on Sun Aug 31 08:32:11 2025
ACUS01 KWNS 311250
SWODY1
SPC AC 311249
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Sun Aug 31 2025
Valid 311300Z - 011200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Overall severe weather potential is expected to be low today and
tonight.
...Discussion...
Modest-strength mid-level northwesterly winds aloft will persist
over the Great Plains, to the east of the Rockies-centered upper
ridge and an upper low off the coastal Pacific Northwest. Weak convergence/subtle surface troughing will be prevalent in
association with a persistently moist air mass across the southern
Plains. Although a few strong storms could occur across parts of Kansas/Oklahoma into Texas this afternoon into evening, the
combination of only modest instability and relatively weak
deep-layer shear should limit the overall severe-weather potential.
A few strong storms could also develop across southwest New Mexico
and southeast Arizona later this afternoon into this evening, with
some stronger wind gusts a possibility.
..Guyer/Bentley.. 08/31/2025
$$
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From
Mike Powell@618:250/1 to
All on Mon Sep 1 09:35:10 2025
ACUS01 KWNS 011253
SWODY1
SPC AC 011252
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Mon Sep 01 2025
Valid 011300Z - 021200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS...
...SUMMARY...
Isolated severe storms may occur across the southern Plains this
afternoon and early evening, including parts of southern Kansas and
western Oklahoma.
...Southern Plains including southern Kansas/western Oklahoma...
A shortwave trough centered over eastern Nebraska this morning will
progress southeastward toward the south-central Plains and
eventually the Ozarks by tonight. This will be in association with a strengthening belt of north-northwesterly mid-level winds (35 kt at
500 mb). While the related low-level/surface response will be muted,
a weak surface front/wind shift will progress southward from Kansas
into Oklahoma, with a relatively moist air mass preceding the
advancing front. Morning low clouds/stratus will abate by afternoon,
yielding to ample insolation and probably a corridor of moderate buoyancy/steepening lapse rates, particularly across southwest
Kansas/northwest Oklahoma. Increasing/widely scattered thunderstorm
development is probable into mid-afternoon near the front/wind shift
as the boundary layer warms. The enhanced north-northwesterly flow
aloft will contribute to 35+ kt effective shear, which could yield
some marginal supercells aside from evolving multicellular clusters.
Isolated instances of severe hail/damaging wind will be possible
through early evening as storms develop south-southeastward from
southern Kansas into western/northern Oklahoma.
..Guyer/Bentley.. 09/01/2025
$$
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From
Mike Powell@618:250/1 to
All on Tue Sep 2 09:18:25 2025
ACUS01 KWNS 021234
SWODY1
SPC AC 021233
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Tue Sep 02 2025
Valid 021300Z - 031200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE UPPER MIDWEST...
...SUMMARY...
Thunderstorms with potential for isolated severe wind gusts and
marginally severe hail will be possible this afternoon into the
early evening across parts of the Upper Midwest.
...Upper Midwest...
An upper trough initially over central Canada will dig southeastward
into the Upper Midwest/Lake Superior vicinity during the period.
Showers and weak thunderstorms ongoing this morning over MN, aided
by an MCV over northern MN, will gradually dissipate with
differential heating/residual outflow arcing from southern MN west-northwestward towards the Dakotas/MN border by mid afternoon.
A cold front initially over ND will advance southeastward
into an adequately moist airmass, featuring surface dewpoints in the
lower to mid 60s F ahead of it. Diurnal heating will likely yield
moderate SBCAPE (1500-2000 J/kg) ahead of the front by mid-late
afternoon. Model guidance is consistent in showing a band of
scattered thunderstorms developing from the eastern half of SD into
central MN by the mid-late afternoon. Upscale growth with higher
storm coverage is expected from near the MN/SD border eastward into
central and southern MN during the 22-02 UTC period. The stronger
mid- and upper-level flow will likely lag behind the surface front
and limit effective shear magnitudes (at or below 25 kt). However,
a few organized multicells could be associated with isolated severe
wind gusts and hail before this activity subsides during the
early-mid evening.
..Smith/Bentley.. 09/02/2025
$$
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From
Mike Powell@618:250/1 to
All on Wed Sep 3 08:26:44 2025
ACUS01 KWNS 031158
SWODY1
SPC AC 031157
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0657 AM CDT Wed Sep 03 2025
Valid 031300Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
KANSAS INTO WESTERN MISSOURI...
...SUMMARY...
Scattered thunderstorms with potential for large to very large hail
and severe wind gusts are expected this afternoon and evening across
parts of the central Plains and lower Missouri Valley.
...Central Plains/Lower Missouri Valley...
Water-vapor imagery this morning shows a mid-level shortwave trough
over southern SD moving quickly southeast as a larger-scale mid- to
upper-level low moves from western ON to near Lake Superior during
the period. The smaller-scale disturbance is forecast to reach the
lower MO Valley by late afternoon with an attendant belt of
moderately strong northwesterly mid- to high-level flow
overspreading the central Plains into the mid MS Valley.
In the low levels, a cold front will advance southward across the
central Plains and lower Missouri Valley with 60s deg F surface
dewpoints ahead of the boundary. Diurnal heating will contribute to
moderate buoyancy by mid afternoon with convective inhibition
eroding near the front. Scattered thunderstorms are forecast to
develop from central KS eastward into the lower MO Valley during the
20-00 UTC period.
The aforementioned strong northwesterly flow in the 500 to 300 mb
layer (35-55 kt) will yield effective shear supporting organized
updrafts. A few supercells will probably evolve across KS and
perhaps into western MO where the main risk will be large to very
large hail. Severe wind gusts will also be possible with
supercells, or small clusters/bowing segments where 0-2 km lapse
rates are steepest (i.e., KS). The severe threat is expected to
persist into the mid evening as several small clusters move
southeastward into southeast Kansas and adjacent portions of
northern OK and southwest Missouri.
..Smith/Bentley.. 09/03/2025
$$
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From
Mike Powell@618:250/1 to
All on Thu Sep 4 08:14:40 2025
ACUS01 KWNS 041233
SWODY1
SPC AC 041231
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0731 AM CDT Thu Sep 04 2025
Valid 041300Z - 051200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
EAST AND THE MIDDLE MISSOURI VALLEY...
...SUMMARY...
Isolated damaging winds are possible across parts of the Northeast
to the southern Appalachians and Tennessee Valley from late morning
through the afternoon. Isolated severe gusts are possible across
parts of the middle Missouri Valley late this afternoon into the
early evening.
...Southern Appalachians/TN Valley to the Northeast...
Isolated to scattered showers/thunderstorms are ongoing this morning
from the Lower Great Lakes southward into the southern Appalachians. Water-vapor imagery shows a vertically stacked cyclone over Ontario
with a disturbance rotating through the basal portion of the larger
scale trough. This mid-level feature will quickly move from the
upper OH Valley into the NY/central Appalachians by the late afternoon.
Despite weak mid-level lapse rates, some diurnal heating ahead of
this activity should yield gradual intensification of thunderstorms
and increased storm coverage by late morning across parts of the
southern Appalachians. Locally damaging winds and marginally severe
hail are possible, centered on the eastern TN vicinity.
Isolated to scattered multicell clusters and short-line segments may
also evolve in the afternoon from convection along/ahead of the cold
front and lee trough. Weak MLCAPE and poor mid-level lapse rates
will temper convective vigor, with damaging wind potential locally
augmented to where pockets of deeper boundary-layer heating occur.
...Mid-MO Valley...
An intense mid-level speed max/shortwave trough will quickly move
from the southern part of the Prairie provinces into the mid MO
Valley by this afternoon, before moving into the southwest Great
Lakes by early Friday morning. Some model spread exists on the
magnitude of destabilization immediately ahead of a cold front
forecast to sweep through the region late this afternoon into the
evening. However, weak buoyancy appears likely to develop and
low-level lapse rates may become adequately steep to support a
narrow corridor of low-topped storms capable of isolated severe gusts.
...KS...
An accelerating and sharpening cold front will sweep south across
the central High/Great Plains tonight. Undercut/elevated convection
should form to the cold side of this boundary early Friday morning.
Locally strong surface gusts may accompany this activity amid robust
low-level northerlies.
..Smith/Bentley.. 09/04/2025
$$
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From
Mike Powell@618:250/1 to
All on Sun Sep 7 08:48:02 2025
ACUS01 KWNS 071210
SWODY1
SPC AC 071209
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0709 AM CDT Sun Sep 07 2025
Valid 071300Z - 081200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN HIGH PLAINS...
...SUMMARY...
A few stronger thunderstorms capable of marginally severe wind
gusts/hail are possible across portions of the central and southern
High Plains late this afternoon through the early evening.
...Central/Southern High Plains...
Morning water-vapor imagery shows a low/trough over the eastern
Pacific with a downstream ridge over the Rockies. A couple of weak disturbances are cresting the ridge and may aid in storm development
later this afternoon/evening over the central High Plains later
today.
In the low levels, a lee trough and an associated moisture plume
over the High Plains will provide a focus for isolated to widely
scattered storms. Strong heating over the High Plains will
contribute to weak to moderate buoyancy by late afternoon.
South-southeasterly low-level winds veering to around 20-kt
northwesterly mid-level flow will support some modest updraft
organization. The stronger storms may yield an isolated severe-hail
(diameter 1.5 inches or less) and wind-gust (55-65 mph) threat. A
small cluster or two is expected to evolve during the evening
coincident with an increase in the LLJ. This activity will likely
move east-southeast into western KS and the OK/TX Panhandles, where
a cooling boundary layer and increasing CINH will act to limit
severe potential by mid-late evening.
..Smith/Broyles.. 09/07/2025
$$
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From
Mike Powell@618:250/1 to
All on Wed Sep 10 08:03:04 2025
ACUS01 KWNS 101247
SWODY1
SPC AC 101245
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Wed Sep 10 2025
Valid 101300Z - 111200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Scattered showers and thunderstorms are possible over parts of the
Northwest and northern Rockies with more isolated storms over the
High Plains. Severe potential is generally low.
...Synopsis...
Water-vapor imagery this morning shows an upper low situated over
northern CA, and it will remain nearly stationary during the period
with a large area of cyclonic flow extending from southern CA into
the eastern Great Basin and central Rockies. A downstream upper
ridge over the High Plains will feature a lee trough that will act
to focus isolated to scattered thunderstorms from MT southward into
the central High Plains.
Strong heating and weak upslope flow beneath the aforementioned
upper-level ridge will favor a few isolated cells developing during
peak heating. A couple of the more vigorous storms may be capable
of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the
CO Front Range in the High Plains, and 3) in eastern WY. Warming
aloft is expected to mitigate the overall potential with these
storms. Farther west, a mid-level shortwave trough will move
through the base of the West Coast mid- to upper low/trough and to
near the UT/NV border by late afternoon/early evening. A
corresponding belt of 50-kt southwesterly 500-mb flow will
overspread western UT. Isolated dry microbursts may accompany the
stronger storms over central UT into western CO during the 22-02z period.
Elsewhere, scattered afternoon storms will occur beneath the upper
trough from northern NV into OR and western ID, and a few of these
storms could produce at least small hail given such cool
temperatures aloft and modest deep-layer shear.
..Smith/Broyles.. 09/10/2025
$$
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From
Mike Powell@618:250/1 to
All on Fri Sep 12 09:25:56 2025
ACUS01 KWNS 121244
SWODY1
SPC AC 121243
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 AM CDT Fri Sep 12 2025
Valid 121300Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
MONTANA EAST ACROSS MUCH OF THE DAKOTAS...AND IN THE FOUR CORNERS REGION...
...SUMMARY...
A few storms capable of isolated severe wind gusts and hail are
possible across the Four Corners region, and from eastern Montana
into the Dakotas.
...Synopsis...
An upper trough will remain over the Intermountain West, making slow
eastward progress through tonight. An embedded disturbance is
forecast to move from CO into the Dakotas late in the day, while a
midlevel jet rounds the base of the trough across AZ overnight.
Gradual height falls will occur across the length of High Plains
primarily overnight as the upper-level ridge to the east gradually
weakens.
...Eastern MT into the Dakotas...
Thunderstorm development/intensification is expected across MT/WY
east of a mid-level trough axis, where cool mid-level temperatures
and surface dew points in the 50s will lead to MLCAPE in the 500 -
locally 1000 J/kg range. Southwesterly deep-layer shear averaging
20-35 kts will be favorable for isolated storms with hail potential.
As storms move/develop farther east across eastern MT/western
ND/northwest SD towards evening, greater instability (MLCAPE on the
order of 2000 J/kg) should result in a severe hail and wind risk
with isolated stronger storms within a similarly-sheared
environment. Although the low-level jet should be weaker in this
area tonight, lingering instability across the western Dakotas
suggests some continued severe risk, primarily for strong/damaging
gusts, into the overnight hours.
...Four Corners Region...
Scattered to numerous thunderstorms are expected to
develop/intensify today from eastern AZ/southeast UT across western
portions of NM/CO, within a moist plume on the eastern periphery of
the mid-level trough. Cool mid-level temperatures will contribute to
modest MLCAPE, with locally higher values (above 1000 J/kg) over
southeastern AZ. A predominantly cellular or cluster mode is
expected, with isolated stronger storms capable of marginally severe
wind and hail. Storms should persist into the evening over western
NM/CO, with a few stronger storms remaining possible.
..Bunting/Broyles.. 09/12/2025
$$
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From
Mike Powell@618:250/1 to
All on Sat Sep 13 09:39:03 2025
ACUS01 KWNS 131243
SWODY1
SPC AC 131242
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Sat Sep 13 2025
Valid 131300Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NEW MEXICO
NORTH INTO THE DAKOTAS...AND OVER PORTIONS OF THE MIDWEST...
...SUMMARY...
Isolated severe wind and hail will be possible from the
Southwest/southern Rockies to the northern Great Plains and a
portion of the Midwest, mainly today into early tonight.
...Southwest/southern Rockies/High Plains...
An increase in thunderstorm coverage is anticipated from CO south
into NM today as ascent/mid-level cooling with the western U.S.
upper trough and several embedded vorticity maxima overspread the
region. Extensive cloud cover will tend to limit the potential for
widespread significant destabilization, with generally modest MLCAPE
(at or below 1000 J/kg) over much of the area from CO southward into northern/western NM. Over portions of southern/eastern NM, however,
higher surface dew points surging northwest from southwestern TX
should help to focus a region of greater instability, with MLCAPE of
1000 to locally near 1500 J/kg possible by afternoon. Ongoing
thunderstorms should expand in coverage and increase in intensity as
diurnal destabilization occurs, with isolated severe hail and wind
possible with the strongest storms.
Over southern/eastern NM, deep-layer shear will be more supportive
of organized updrafts as a belt of stronger mid-level flow develops
near the base of the trough, resulting in elongated hodographs.
Here, a somewhat more concentrated risk for severe hail and wind may
develop with a couple storms developing supercell structures. Higher
severe probabilities were considered for this area, however
lingering concerns over the effects of ongoing storms and related
cloud cover lowered confidence in increasing probabilities with this outlook.
...NE/SD/ND...
Strong storms were ongoing this morning over portions of the western
Dakotas in association with embedded impulses in advance of the
upper trough. The resulting extensive cloud cover/outflows from
multiple rounds of thunderstorms will tend to temper destabilization
later today within a modestly-sheared environment. Nevertheless,
some isolated severe wind/hail potential will exist as storms over
central SD move into ND today. Thunderstorms are expected to
redevelop across the central High Plains of NE/northeast CO later
this afternoon and evening and move into western SD tonight. Here,
sufficient diurnal destabilization in the wake of earlier convection
may result in a continued risk for isolated severe storms with
strong-damaging gusts and hail.
...IL/IN/WI...
A small cluster of thunderstorms over northeast IL/northwest IN,
associated with an earlier MCV over WI and ongoing/modest warm
advection, is expected to continue moving SSE in the short term
across eastern IL/far western IN. Some isolated severe wind and hail
potential may develop as this cluster of storms moves along an
intensifying instability gradient within a northwest flow regime
through at least early afternoon as boundary layer heating commences.
..Bunting/Broyles.. 09/13/2025
$$
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From
Mike Powell@618:250/1 to
All on Mon Sep 15 09:45:29 2025
ACUS01 KWNS 151244
SWODY1
SPC AC 151242
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Mon Sep 15 2025
Valid 151300Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WYOMING
INTO WESTERN SOUTH DAKOTA...OVER FAR NORTHERN MINNESOTA...AND
NORTHEAST NORTH CAROLINA...
...SUMMARY...
Isolated severe gusts are possible across Wyoming into western South
Dakota this afternoon to early evening. Isolated severe hail and
damaging wind are possible across far northern Minnesota in the
early to mid-afternoon. A brief tornado is possible in the northeast
North Carolina vicinity in the early morning Tuesday.
...WY to western SD...
A shortwave trough over western ID will move east across WY/western
SD during the day, as several embedded vorticity maxima contribute
regions of enhanced ascent. Steep mid-level lapse rates of 8-9 deg
C/km, combined with diurnal heating, will result in MLCAPE of a few
hundred J/kg across much of the area. Despite weak buoyancy, the favorably-timed ascent will contribute to thunderstorm development/intensification this afternoon as storms approach
northeast WY/western SD. A deep and well-mixed boundary layer will
lead to high-based convection capable of isolated strong/damaging
gusts through early evening, with intensities diminishing thereafter
as nocturnal cooling commences.
...Northeast NC/southeast VA vicinity...
A surface low southeast of Cape Hatteras is forecast to move towards
the NC coast through 12z Tuesday, with a belt of stronger low-level
flow developing north/northwest of the low. Variability remains
regarding the forecast location of the low and strength of low-level
winds, however a conditional risk for a tornado would exist early
Tuesday morning with stronger convective elements, should sufficient
low-level hodograph curvature develop, as high theta-e air is
advected west across the northeast NC/southeast VA vicinity.
...Far northern MN...
Thunderstorm development is expected this afternoon within a northwest-southeast oriented arc from southeast Manitoba across
northeast Ontario as a shortwave trough becomes increasingly
negatively tilted while lifting northeast. Although development
south of the international border is uncertain, some CAM guidance
suggest isolated development is possible. Moderate buoyancy and
effective shear of 35-40 kts over far northern MN suggests a
conditional risk for severe wind/hail would exist should storm
development occur in this area.
...MO/AR vicinity...
A few strong gusts will be possible again today with pulse-type
storms within a weakly-sheared but strongly unstable (MLCAPE of
2500-3000 J/kg) environment.
..Bunting/Broyles.. 09/15/2025
$$
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