999
ACUS01 KWNS 241632
SWODY1
SPC AC 241630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Aug 24 2025

Valid 241630Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL HIGH PLAINS...AND PORTIONS OF NEW YORK AND
PENNSYLVANIA...

...SUMMARY...
A few severe thunderstorms should develop this afternoon and evening
across the southern/central High Plains spanning from eastern
Colorado into western Oklahoma. Scattered strong to severe
thunderstorms are also possible across portions of Pennsylvania and
New York.

...Southern/Central High Plains...
Elevated thunderstorms are ongoing late this morning across parts of
western/southern KS in a northwesterly mid-level flow regime. This
activity has generally remained sub-severe, but the stronger cores
could be capable of producing occasional hail as they track
southeastward this afternoon given the presence of sufficient MUCAPE
and deep-layer shear. Modestly enhanced mid-level flow is expected
to remain over parts of the central into southern Plains today,
generally from eastern WY/CO into western KS/OK and vicinity,
between a mid/upper-level anticyclone over the Southwest and
mid/upper-level troughing across the Upper Midwest. A surface front
extends from northern CO into western KS. This boundary, along with
outflow from ongoing convection, may serve as foci for robust
thunderstorm development later today.

There is still a fair amount of uncertainty regarding convective
development and evolution this afternoon/evening across the
southern/central High Plains given weak forcing aloft. Modest
low-level upslope flow and orographic effects should encourage at
least isolated thunderstorms to initially develop over the higher
terrain of the central Rockies/Front Range, and subsequently spread
southeastward into the High Plains through the evening. The
front/outflow boundary draped from northeast CO into southwest KS
could also serve as a forcing mechanism to aid parcels in reaching
their LFCs. The environment along/south of the front should become
moderately unstable with continued daytime heating, with greater
low-level moisture present across western KS into the OK/TX
Panhandles and western OK.

Modest low-level southeasterlies should persist through much of the
afternoon/evening along and near the front, which should locally
enhance 0-1 km SRH. It appears possible that a supercell or two
could develop near the front later today and track
south-southeastward in a favorable northwesterly mid-level flow
regime. Isolated large hail would probably be the main threat if a
supercell can be sustained, with perhaps a tornado also possible
where low-level flow can remain backed to southeasterly near the
front. Some guidance suggests a cluster or two may eventually emerge
this evening across eastern CO and/or southwest KS, but this
potential remains highly uncertain. Mesoscale trends will be
monitored for a zone of more focused severe potential and possible
outlook upgrade.

...New York/Pennsylvania...
An amplified upper trough/low over Ontario and extending southward
into the Great Lakes/Midwest is forecast to gradually shift eastward
today. A related surface cold front will also advance
east-southeastward through the period across parts of the Northeast
and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly
moist low-level airmass ahead of the front will promote weak to
locally moderate instability this afternoon, especially across parts
of PA/NY. Current expectations are for thunderstorms to develop
along/near the front through the afternoon across western PA/NY.
While mid-level lapse rates are forecast to remain poor, which will
likely limit updraft strength, sufficient deep-layer shear should be
present to support some thunderstorm organization. Loosely organized
clusters/cells may pose an isolated threat for damaging winds and
perhaps marginally severe hail as they spread eastward across
central PA and central/northern NY through early evening. This
activity should weaken with eastward extent as it encounters a less
unstable airmass.

..Gleason/Moore.. 08/24/2025

$$