847
ACUS02 KWNS 201639
SWODY2
SPC AC 201637

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1137 AM CDT Sun Sep 20 2026

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM MISSISSIPPI
TO THE CENTRAL/SOUTHERN APPALACHIANS...

...SUMMARY...
A few instances of damaging gusts are possible across the central
and southern Appalachians to northern and central Mississippi on
Monday.

...Central Appalachians to MS...

Modest westerly deep-layer flow will overspread the Ohio Valley to
central Appalachians ahead of a weak mid/upper shortwave trough
shifting east from the central/southern Plains to the MS Valley. At
the surface, a cold front will extend from the Mid-South through the
Ohio Valley into the Mid-Atlantic early in the forecast period. This
front will sag southward through the period, becoming oriented from
the TN Valley to the Carolinas by early Tuesday. Ahead of the
boundary, a moist airmass characterized by mid 60s to low 70s F
dewpoints will be in place. Where stronger heating occurs, moderate
destabilization is expected. Vertical shear is expected to be weak,
with effective shear magnitudes generally less than 15 kt. This
should limit organized convection, with mainly pulse thunderstorm
activity anticipated. PW values around 1.5-1.75 inches could support
sporadic strong gusts. Storm coverage is expected to be isolated to
widely scattered and overall risk limited by marginal environmental
parameters.

...Far eastern NM into central TX...

Isolated to scattered thunderstorms are expected to develop within
an easterly/low-level upslope flow regime along a south/southwest
moving surface cold front. Vertically veering wind profiles will
result in modest effective shear, but deep-layer flow will be very
weak. Additionally, weak capping between 850-700 mb in evident in
forecast soundings. A narrow corridor of 1000-1500 J/kg MLCAPE is
forecast, though midlevel lapse rates will remain modest. Any storms
that develop could also quickly become undercut by the surface cold
front. Where stronger heating occurs, occasional gusty winds are
possible, but overall severe risk appears too limited to include
unconditional probabilities at this time.

..Leitman.. 09/20/2026

$$