870
ACUS01 KWNS 210602
SWODY1
SPC AC 210600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1200 AM CST Fri Nov 21 2025

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
MS/AL/TN...

...SUMMARY...
Isolated strong to severe storms are possible later today into
tonight across parts of Mississippi and Tennessee into western and
northern Alabama.

...Synopsis...
A mid/upper-level shortwave trough is forecast to deamplify and move
quickly eastward from the central Plains toward the Ohio Valley
later today into tonight. In conjunction with this shortwave, a weak
surface low will move eastward from southern MO to near the TN/KY
border, along a diffuse surface boundary. Farther west, a
mid/upper-level cyclone will move southeastward off the coast of
southern CA.

...Parts of the Southeast/TN Valley...
A Marginal Risk has been added across parts of MS/AL/TN. While
modest instability will tend to limit the magnitude of the severe
threat, relatively favorable wind profiles atop seasonably rich
low-level moisture could result in a threat for a brief tornado
and/or locally damaging wind.

Dewpoints in the 60s to near 70 F will spread northward across parts
of MS/AL/TN later today, in response to the shortwave trough and
weak surface low approaching the Ohio Valley. Morning convection and
remnant cloudiness will tend to limit diurnal heating, and midlevel
lapse rates will remain weak. However, weak capping will allow for
scattered diurnal storm development from southern/central MS into
western AL. While stronger mid/upper-level flow and large-scale
ascent will be displaced to the north, moderate deep-layer shear and
modest low-level veering of the wind profile could support at least
transient storm organization, with a threat of locally damaging wind
and perhaps a brief tornado.

Farther north into northern MS/AL and parts of TN/far southern KY,
guidance depicts renewed storm development during the evening into
late tonight, aided by the glancing influence of the departing
shortwave trough. Deep-layer flow will remain rather strong across
this region, so an isolated severe threat could evolve if sufficient
recovery and destabilization can occur. If organized convection can
be sustained within this regime, then a threat for a brief tornado
and/or locally damaging wind could develop later tonight.

...Middle/upper TX Gulf Coast...
Isolated to scattered storms will likely be ongoing later this
morning across the TX coastal plain, with some redevelopment
possible later this afternoon or evening along a cold front. While
deep-layer shear will remain somewhat favorable for storm
organization, weakening large-scale ascent and warming temperatures
aloft are currently expected to limit severe potential. If any
organized convection can persist from overnight, and/or if
substantial destabilization can occur along/ahead of the front
during the afternoon, then a few strong storms will be possible.

...Southern California...
Isolated storms will be possible across parts of the Southwest, in
association with the mid/upper-level cyclone. The strongest
instability will remain near and offshore of the southern CA coast,
and low-level flow is expected to generally be weak, but a strong
storm or two cannot be ruled out, especially early in the day.

..Dean.. 11/21/2025

$$