RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1029 AM CST Fri Nov 21 2025
Valid 211630Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
MS/AL/TN/KY...
...SUMMARY...
Isolated strong to severe storms are possible today and tonight
across parts of Mississippi and Tennessee into western and northern
Alabama and possibly southern Kentucky.
...MS/AL/TN/KY...
A strengthening of deep-layer flow will occur regionally in tandem
with the eastward progression of a low-amplitude shortwave trough
from the Lower Missouri Valley toward the Lower Ohio River Valley
tonight, with height falls remaining limited south of the Tennessee
Valley.
The more organized/sustained scattered thunderstorms this afternoon
will probably remain focused within the warm conveyor from
south-central Mississippi into Alabama. On the south-southwest
periphery of these storms, there will be a gradual northeastward
expansion of the effective warm sector while destabilization will
still remain weaker with eastward extent. Mid-level lapse rates are
weak, suggesting most updrafts will struggle to intensify. However,
strong deep-layer shear and moderately strong low-level shear/SRH,
particularly within the aforementioned corridor, could support a
couple of rotating storms capable of a tornado or damaging wind.
The primary surface cold front will move into this region tonight,
with another round of showers and thunderstorms expected to uptick
this evening across the Mid-South including western Tennessee and
northern Mississippi. Low-level winds are expected to veer by this
time, reducing low-level shear/SRH. Nevertheless, a low risk of a
tornado and/or gusty winds will exist.
..Guyer/Kerr.. 11/21/2025
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 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 tomorrow (Saturday), though severe
thunderstorm potential appears low.
...Synopsis...
A broad mid-level trough, with multiple embedded impulses, will
progress across the eastern U.S. as upper ridging builds over the
Plains, and an upper low overspreads the Southwest tomorrow
(Saturday). With the evolution of this upper pattern, surface high
pressure and accompanying cooler, stable air will overspread most of
the central and northern CONUS, limiting thunderstorm potential.
From southeast TX to the coastal Carolinas, widely scattered
thunderstorm development is possible ahead of a surface cold front,
which will be ushered southeast by the aforementioned mid-level
trough, toward a seasonably moist low-level airmass. Thunderstorms
will also be possible across portions of the Desert Southwest into
western TX, beneath the progression of the upper low, which may
evolve into an upper wave through Saturday. Cooler temperatures
aloft will promote buoyancy (albeit scant) for thunderstorm
development.
...Southeast VA into central and eastern NC...
In roughly the 18-00Z period, isolated to widespread scattered
thunderstorm development is possible ahead of the cold front, aided
further by upper support with an overspreading embedded mid-level
impulse. Overlapping 60-70 kt 500 mb westerly flow atop 25+ kt
west-southwesterly 850 mb winds will yield elongated, straight
hodographs and 40+ kts of effective bulk shear. Through the day,
diurnal heating will support upper 60s/mid 70s F surface
temperatures amid 60+ F dewpoints. These low-level thermodynamic
conditions should yield around 500 J/kg MLCAPE via tall/thin
buoyancy profiles given modest tropospheric lapse rates. While gusty
conditions and perhaps some hail may accompany the stronger storms,
organized severe wind/hail seems unlikely, with severe probabilities
withheld for now.
...Southern and central AZ into southwestern NM...
A nearly vertically stacked upper low (from roughly 850 mb on up)
will overspread AZ and NM through the period. A belt of stronger,
mostly unidirectional flow in the 850-500 mb layer will pivot around
the low and overspread portions of southern into central AZ and
southwestern NM in the 00-12Z time frame. This flow, resulting in
elongated hodographs (and 35-45 kts of effective bulk shear) will
coincide with 7.5-8 C/km mid-level lapse rates, supporting
multicells capable of at least small hail. Since these favorable
conditions will be overspreading an overnight (potentially stable)
boundary layer, MUCAPE should be thin, and only reach a few hundred
J/kg. As such, the current thinking is that buoyancy may be too
limited to support severe probabilities.
..Squitieri.. 11/21/2025
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