Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CDT Mon Sep 21 2026
Valid 211630Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE SOUTHEAST INTO CENTRAL APPALACHIANS...AND OVER THE TEXAS SOUTH
PLAINS...
...SUMMARY...
Isolated damaging wind gusts are possible this afternoon from parts
of the Southeast into the southern and central Appalachians. An
isolated risk for large hail and severe gusts is forecast over parts
of the Texas South Plains later today.
...Southeast/Southern and Central Appalachians...
Recent radar and satellite imagery reveals a trio of MCVs over the
OH Valley, with perhaps another MCV farther southwest in the
Mid-South vicinity. These vorticity maxima are north/west of an
arcing cold front that extends from southern VA west-northwest into
northern KY and then back southwestward through northern AR and
central OK into the TX South Plains. A moist airmass persists south
of this boundary, with dewpoints in the low 70s across much of
Southeast, TN Valley, and Carolinas. The front is forecast to slowly
shift southward today, interacting with the moist, diurnally
destabilized, and moderately buoyant airmass to support scattered
thunderstorms. Vertical shear will be weak, and largely
multicellular, outflow-dominant storm mode is anticipated. Even so,
ample moisture is in place (i.e. PW values over 2" sampled on the
12Z BMX sounding), and sporadic stronger downdrafts may yield a
strong to locally severe gusts (50 to 60 mph). Highest thunderstorm
coverage is expected from southeast TN and northwest GA through
northern AL into central/southern MS and eastern LA.
...TX South Plains into north-central/northeast TX...
Western periphery of the front described in the previous section
intersects a weak low over far southeast NM. A moist airmass exists
along and south of this boundary, with dewpoints ranging from the
low 60s over the TX South Plains to the low 70s across much of
central and eastern TX. Easterly flow will help maintain this
moisture amid strong heating over the TX South Plain vicinity,
contributing to airmass destabilization and moderate buoyancy by
this afternoon. Low-level convergence along the front (and/or
residual outflow) and near the surface low will likely result in
scattered thunderstorm development. Vertical shear will be modest,
but any stronger, more persistent thunderstorms may yield an
isolated risk for large hail/severe gusts before dissipating during
the evening.
A secondary area of higher thunderstorm coverage appears likely over
northeast TX this afternoon/evening. Here, differential heating
and/or outflow from ongoing thunderstorms could result in an area of
increased low-level convergence within a warm, moist, and moderately
unstable airmass this afternoon. Isolated water-loaded downbursts
capable of producing damaging wind gusts are possible. Anticipated
limited severe coverage precludes introducing low wind probabilities
in this area.
..Mosier/Chalmers.. 09/21/2026
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