Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sun Aug 24 2025
Valid 242000Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO
INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA
PANHANDLE...
...SUMMARY...
A few severe thunderstorms are expected 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.
...20z Update...
An upgrade to Slight was made with this update in eastern
Colorado/western Kansas. Thermodynamics and shear profiles are
favorable for supercell development. Recent development on radar
suggests attempts are ongoing across portions of eastern Colorado
near the Palmer Divide and near Colorado Springs. Any more discrete
supercells that can be maintained will pose a risk for large hail,
and as such a 15% was added with this update. See MCD#2009 for more
information.
..Thornton.. 08/24/2025
.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/
...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.
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