RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
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
Read more
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CST Fri Nov 21 2025
Valid 221200Z - 231200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are possible from the Southwest into the
southern Plains and Southeast on Saturday, though severe
thunderstorm potential appears low.
...Discussion...
Multiple embedded shortwave troughs will exist within the broader
trough across the Great Lakes and the East Coast. Shortwave ridging
will build across the southern/central Plains ahead of an upper-low
across the Southwest which will start to become a more broad/open
wave by the end of the period. A cold front will extend from the
North Carolina coast through the Southeast. Weak instability is
forecast south of this front where low to mid 60s dewpoints are
present. However, forcing will be weak amid negligible frontal
convergence and neutral height tendencies aloft.
As a mid-level jet streak emerges across the southern High Plains
early Sunday morning, a locally favorable environment for small hail
may develop on the leading edge of this jet streak. A strengthening
low-level jet and increasing low-level moisture will result in
moderate instability across the region. In addition, the
strengthening mid-level flow will result in a favorable wind profile
for supercells. Small hail appears most likely at this time, but if
greater instability develops, isolated large hail is possible early
Sunday morning.
..Bentley.. 11/21/2025
Read more
SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0225 AM CST Fri Nov 21 2025
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
TEXAS TO THE RIO GRANDE...
...SUMMARY...
Isolated severe thunderstorms are possible across portions of
central Texas to the Rio Grande on Sunday. Large hail and damaging
wind gusts will be the primary threats.
...Synopsis...
A closed mid-level low across the Southwest will become an open wave
as it moves into the Plains on Sunday. Weak surface troughing is
forecast to develop across the High Plains during the day.
Strengthening southerly flow east of this surface trough will bring
rich moisture northward across central Texas as a warm front lifts
northward.
...Central Texas to the Rio Grande...
Strengthening low-level flow will continue to destabilize the
boundary layer through the day as a warm front lifts north. As
isentropic ascent increases during the afternoon/evening, widespread
thunderstorm activity is anticipated along the warm front and also
along the cold front/dryline. Moderate instability and strong shear
will support the potential for mostly elevated supercells capable of
isolated large hail. As storms grow upscale, the threat for damaging
wind gusts will increase during the late evening and into the
overnight period. Initially, expect convection to be elevated, but
it may eventually become more surface based as storms advance into
the warm sector. Low-level lapse rates will be very weak (3-4 C/km)
which should keep any tornado threat isolated. However, given the
strong low-level shear, an isolated tornado cannot be ruled out.
..Bentley.. 11/21/2025
Read more
