RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 AM CST Thu Nov 20 2025
Valid 201300Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS INTO 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 into Arkansas...
A mid/upper-level trough extending from the Southwest into northern
Mexico this morning will eject northeastward across parts of the
southern Plains today. In response, a surface low will gradually
deepen across the south-central High Plains and develop eastward
through the period. A front extending across parts of OK/AR this
morning will lift slowly northward as a warm front ahead of the
surface low. Thunderstorms ongoing across parts of the southern
Plains/ArkLaTex this morning are being aided by a modest low-level
jet and ascent attendant to the approaching upper trough. Weak to
locally moderate instability and effective shear of 40-50 kt may
support a few strong to severe thunderstorms this morning from parts
of eastern NM into west/central TX and OK, with a threat for mainly
isolated hail and locally gusty winds.
Convection and widespread cloud cover will likely 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. Still, depending on the extent of
heating and related destabilization, most guidance continues to show
some potential for isolated supercells and/or organized multicell
clusters this afternoon/evening across portions of TX, with a threat
of isolated severe hail and damaging winds. Modest enlargement of
low-level hodographs with time could also support a tornado threat
from parts of central/east TX into eastern OK/western AR along and
south of the warm front, assuming surface-based supercells can be
sustained. An isolated severe risk may persist into east TX and the
ArkLaTex tonight. However, confidence in a corridor of greater
severe risk remains too low to include higher severe probabilities
at this time.
Farther west, some high-resolution guidance continues to show the
development of a modestly organized convective line across far
eastern NM into west TX during the afternoon/evening, 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 a severe threat. Have therefore maintained the Marginal Risk
across this region with only minor changes.
..Gleason/Broyles.. 11/20/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0309 AM CST Thu Nov 20 2025
Valid 231200Z - 281200Z
...DISCUSSION...
...Days 4-6/Sun-Tue -- Southern Plains to the TN Valley...
An upper low and attendant trough over the Southwest/northern Mexico
will eject east into the Plains by early Day 5/Monday. Gulf
moisture will spread northward across portions of TX into the Lower
MS Valley through early Tuesday. This moisture return will occur
ahead of the ejecting trough/increasing deep-layer southwesterly
flow, and a cold front sweeping across the region. Warm advection
will support thunderstorm development by late Sunday as the upper
trough and cold front begin to march across TX, and some hail risk
could accompany this activity. However, storm mode could preclude a
greater risk, and storm coverage/intensity is uncertain given
overnight timing.
As this system continues east across the ArkLaTex into the Lower MS
Valley on Monday, some severe potential could persist into these
areas. However, uncertainty regarding moisture return and degree of
destabilization due to potentially ongoing and widespread training
precipitation precludes severe probabilities at this time. Some risk
could continue across parts of the TN Valley/Southeast into Tuesday.
However, the upper trough is expected to be weakening and lifting
well north of the region by this time.
...Days 7-8/Wed-Thu...
The surface front will move offshore on Day 7/Wed and strong surface
high pressure will build across much of the CONUS. This will result
in dry and colder conditions, leading to a stable airmass. Severe
potential appears low mid to late in the week.
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