RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1031 AM CST Thu Nov 20 2025
Valid 201630Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS TO ARKANSAS...
...SUMMARY...
Isolated strong to severe thunderstorms may occur today into this
evening across the southern Plains into Arkansas. Large hail,
damaging winds, and a tornado or two all appear possible.
...Southern Plains to Arkansas...
Showers/thunderstorms remain common at late morning with widespread
cloud cover with the warm sector across most of Texas and Oklahoma.
This precedes a mid/upper-level trough currently located over
Arizona/New Mexico and far northern Mexico, which will continue to
eject northeastward toward the southern High Plains. A surface low
will gradually deepen across the south-central High Plains and
develop eastward through the period.
It still seems likely that convection and widespread cloud cover
will persist through the day, resulting in generally modest diurnal
heating and weakening mid-level lapse rates with time. While
enhanced deep-layer shear will remain across the warm sector owing
to persistent strong southwesterly mid-level flow, the potential for
organized thunderstorms downstream or in the wake of ongoing morning
convection remains uncertain, particularly in the context of
somewhat stronger low-level winds more likely to interface where
convective overturning has occurred.
Regardless, some potential for isolated supercells and/or organized
multicell clusters will exist this afternoon/evening particularly
across portions of central and possibly into parts of
North/northeast Texas. This includes isolated severe hail and
damaging winds, and a modest enlargement of low-level hodographs
could also support a tornado risk.
Farther west, some high-resolution guidance continues to show the
development of additional strong/locally severe storms across
east/southeast New Mexico into west Texas/southwest Oklahoma, in
closer proximity to the ejecting upper trough. This convection could
pose a threat of strong gusts and perhaps some hail, but it remains
uncertain as to whether sufficient instability will develop to
support anything beyond a very isolated/marginal-type severe risk.
..Guyer/Mosier.. 11/20/2025
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CST Thu Nov 20 2025
Valid 211200Z - 221200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Scattered thunderstorms are expected from the Texas coast to the
central Appalachians tomorrow (Friday). Severe thunderstorms appear
unlikely.
...Synopsis...
A mid-level shortwave trough will traverse the TN Valley as an upper
low meanders over southern CA tomorrow (Friday). Isolated lightning
flashes may occur across southern CA into southwestern AZ as lift
and cooler temperatures aloft overspread the region in association
with the upper low. Across the TN Valley, the passage of the
aforementioned mid-level shortwave trough will encourage a low-level
warm-air advection regime. Modest upper support, in tandem with
mediocre buoyancy (driven primarily by low-level moisture) will
support isolated to scattered thunderstorms from eastern TX to the
central Appalachians through the day tomorrow.
...TN Valley Friday night...
As the low-amplitude mid-level shortwave trough overspreads the TN
Valley, low-level flow (however moist) should become highly veered
through the day Friday, resulting in unidirectional wind fields and
substantially reduced low-level convergence. However, by Friday
night (i.e. 03-09Z time frame), guidance does hint at a small
mid-level impulse traversing the TN Valley. Locally stronger flow
aloft with this impulse will support some speed shear/elongated
hodographs, resulting in 40+ kt effective bulk shear across the warm
sector ahead of an approaching surface cold front. An uptick in
thunderstorm coverage may occur during this time, and some of these
storms may become organized. Still, buoyancy will be weak, with no
more than a few hundred J/kg of thin MLCAPE given poor tropospheric
lapse rates. A stronger, sustained storm capable of producing a
damaging gust or brief tornado would be plausible with the
anticipated vertical wind shear given better buoyancy. However, the
current thinking is that buoyancy may be too limited to warrant
severe probabilities at this time.
..Squitieri.. 11/20/2025
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0131 PM CST Thu Nov 20 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.
...Synopsis...
An upper-level low will translate to an open wave while impinging on
the southern High Plains, with a broad mid-level trough poised to
traverse the Eastern Seaboard on Saturday. As a result, widespread
surface high pressure will overspread much of the central and
northern CONUS, limiting thunderstorm potential for these areas.
Adequate moisture ahead of the surface cold front, along with
frontal convergence, will encourage isolated to scattered
thunderstorm development Saturday afternoon and evening across
portions of eastern TX to the Carolina coastline. A few lightning
flashes are also possible across portions of AZ into NM as cold air
aloft from the upper low coincides with synoptic ascent of a
marginally moist, unstable airmass. Low-level moisture may be
locally more robust into western TX, where surface lee troughing,
encouraged by the approaching mid-level trough, will promote
warm-air/moisture advection from the Gulf. While the moist
southeasterly flow beneath 60-80 kt southwesterly 500 mb winds will
promote strong low-level shear, modest mid-level lapse rates atop a
stable boundary layer should limit the severe threat.
..Squitieri.. 11/20/2025
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