Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0702 AM CDT Sat Aug 22 2026
Valid 221300Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY INTO THE CENTRAL APPALACHIANS...
...SUMMARY...
Thunderstorms capable of producing scattered damaging winds should
occur this afternoon across parts of the Ohio Valley into the
central Appalachians, with isolated damaging winds possible across
the lower Mississippi Valley to the southern Plains/Ozarks. Isolated
hail and damaging winds may also occur over parts of the central
Plains and northern Rockies into the Northwest.
...Ohio Valley into the Central Appalachians and Tennessee/Lower
Mississippi Valleys...
Upper troughing over Ontario and the Great Lakes will advance slowly
eastward today across the OH Valley/Midwest in tandem with a weak
surface cold front. Latest visible satellite imagery this morning
shows mostly clear skies present across the upper OH Valley
vicinity. While low-level moisture will remain fairly modest
(surface dewpoints generally in the 60s) and lapse rates aloft will
be near moist adiabatic, it still appears likely that around
1000-2000 J/kg of MLCAPE will develop ahead of the front by early
afternoon. A gradual increase in thunderstorm coverage and intensity
is expected, with 20-30 kt of effective bulk shear fostering enough
updraft organization for multicell clusters capable of producing
scattered damaging winds. These thunderstorms will spread eastward
from the upper OH Valley into the central Appalachians this
afternoon and evening before eventually weakening with eastward
extent. Isolated hail may occur with the stronger cores that
develop, but the poor mid-level lapse rates present may limit this
threat to some extent. There also appears to be some chance for
strong to locally severe thunderstorms to develop along/east of the
Blue Ridge Mountains this afternoon. If this occurs, then occasional
damaging winds would be the main threat with this activity.
There may be less thunderstorm coverage with southwestward extent
along/ahead of the front into the TN Valley/Mid-South, as
large-scale ascent will be weaker across these regions. Still, any
convection which can develop and be sustained will exist in a
favorable environment for damaging winds, with moderate to strong
instability and sufficient deep-layer shear present to support
multicell clusters.
...Southern/Central Plains into the Ozarks...
On the eastern periphery of upper ridging over the
Southwest/Rockies, thunderstorms have developed early this morning
across parts of the southern/central Plains. This convection is
being aided by modest low-level warm/moist advection, and multiple
weak mid-level disturbances moving through the northwesterly
mid-level flow across the Plains. While substantial MLCIN is
present, sufficient MUCAPE coupled with moderate to strong
deep-layer shear should continue to support updraft organization.
Isolated hail and strong to locally severe gusts may occur with the
more robust cores, and severe probabilities have been adjusted to
account for ongoing convection. Subsequent development of
thunderstorms this afternoon will be dependent on how this morning's
convection evolves, with some weakening possible as a modest
low-level jet gradually lessens over the next several hours. Still,
redevelopment is forecast this afternoon along/south of a weak
front. Moderate to locally strong instability, very steep low-level
lapse rates, and moderate northwesterly deep-layer shear should
support some clustering/updraft organization. Occasional hail and
severe gusts may occur as thunderstorms spread southward across the
southern Plains/Ozarks this afternoon/evening.
A separate area of convection is forecast to develop this afternoon
along the Front Range/Laramie Mountains in a weak post-frontal
low-level upslope regime. While effective bulk shear should be
somewhat weaker across this region, a narrow corridor of greater
instability is forecast across the central High Plains. This may
support loosely organized multicells and marginal supercell
structures with an isolated severe hail/wind threat. This activity
should spread slowly southeastward off the higher terrain before
weakening this evening with the loss of daytime heating.
...Great Basin/Northern Rockies into the Northwest...
Upper ridging will remain prominent from the Southwest into the
northern Rockies/High Plains today. On the western periphery of this
ridging, an upper trough/low will move northward along/near the
coast of the Pacific Northwest. Enhanced south-southwesterly
mid-level flow will overspread parts of the Great Basin, northern
Rockies, and Northwest through the period, with the strongest winds
forecast over WA/OR. Low-level moisture remains fairly limited over
most of these regions, with somewhat greater surface dewpoints
present over parts of the Great Basin.
Diurnal heating should support modest destabilization and weak
instability from the northern Great Basin into the interior Pacific
Northwest and northern Rockies. Thunderstorms will develop this
afternoon as the large-scale ascent preceding the upper trough/low
overspreads these regions in tandem with orographic effects across
the higher terrain. Where low-level lapse rates can become
sufficiently steepened with a dry/well-mixed sub-cloud layer,
isolated severe/damaging winds may occur. The overall severe threat
should be limited by weak instability.
..Gleason/Broyles.. 08/22/2026
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/TV7CzF
