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ACUS01 KWNS 230546
SWODY1
SPC AC 230544
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 AM CDT Sat Aug 23 2025
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL HIGH PLAINS....
...SUMMARY...
Strong to isolated severe storms are possible in the central High
Plains today.
...Synopsis...
A mid-level trough will amplify across the Great Lakes today with
strengthening mid-level flow across the Northern Plains. Surface
high pressure building into the northern Plains this morning will
advance into the central Plains by this afternoon and push a cold
front south across the Plains and Upper Midwest. Farther east, a
cold front, associated with the mid-level trough across the northern
Great Lakes, will move across the Great Lakes and Ohio Valley.
...Central High Plains...
Upslope flow in the wake of the cold front across the central High
Plains may provide an environment favorable for a few isolated
strong to severe storms this afternoon/evening. Terrain driven
storms are anticipated across much of the central Rockies. A few
storms are expected to move off of the higher terrain, and with
support from low-level upslope flow, maintain themselves along the
Front Range as they move south. Steep mid-level lapse rates and
around 35 to 40 knots of mid-level flow will support the potential
for isolated supercell structures capable of isolated large hail and
severe wind gusts. Storm motions around 350 degrees and storm
formation expected along the mountains and immediate foothills will
result in a very narrow area of risk along the Front Range from
southeast Wyoming to central Colorado. Slightly stronger instability
across southeast Colorado and the potential for some clustering of
storms supports a slightly wider marginal extending into this
region.
...Great Lakes...
A few showers and thunderstorms will likely develop along a cold
front as it moves across the Great Lakes this afternoon. Warm 700mb
temperatures in the presence of only low 60s dewpoints will limit
overall buoyancy and updraft strength. Therefore, no severe
thunderstorms are expected.
..Bentley/Weinman.. 08/23/2025
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20250823T0546.txt
028
ACUS01 KWNS 230059
SWODY1
SPC AC 230057
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0757 PM CDT Fri Aug 22 2025
Valid 230100Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS TO THE UPPER MIDWEST...
...SUMMARY...
Isolated strong to locally severe thunderstorms may occur this
evening and into tonight 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.
...Upper Midwest...
A cluster of storms across northern Wisconsin and the UP has now
moved into Canada and is weakening on the eastern periphery of the
better instability. In the wake of this activity, a few storms have
developed along a cold front moving through northern Minnesota with
a few isolated showers/storms developing ahead of it. Have adjusted
the thunder line west to account for these storms and will keep the
marginal across southeast Minnesota and northwest Wisconsin where
instability remains. This threat will likely only continue for a few
more hours before a cooling boundary layer stabilizes the area.
...Central Plains into the central High Plains...
The earlier cluster of storms across eastern Nebraska moved south
and weakened as it moved into a more stable airmass across southern
Nebraska. However, an additional storm developed across east-central
Nebraska where 2000 J/kg MLCAPE is present. This threat may remain
for a few more hours before eventual nocturnal stabilization ends
the threat.
Storms across Wyoming and northeast Colorado have been relatively
weak thus far. However, as heights continue to fall across the
region, expect these storms to maintain with additional storm
development also possible. Weak to moderate instability with 30 to
35 knots of shear will support the potential for isolated strong
storms capable of large hail or severe wind gusts this evening and
into the early overnight hours.
..Bentley.. 08/23/2025
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20250823T0059.txt
822
ACUS01 KWNS 222003
SWODY1
SPC AC 222001
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 PM CDT Fri Aug 22 2025
Valid 222000Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS 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.
...20z Update...
Minor adjustments were made to remove thunder chances and the
Marginal Risk behind ongoing convection from Iowa to Wisconsin.
Otherwise, the forecast remains on track. See previous discussion
below for more information.
..Thornton.. 08/22/2025
.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 22 2025/
...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.
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20250822T2003.txt
189
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
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20250822T1632.txt
