RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0634 AM CST Mon Nov 17 2025
Valid 171300Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Scattered thunderstorms should occur this evening and overnight
across parts of the northern/central Plains into the Ozarks and mid
Mississippi Valley. Isolated thunderstorms are also possible across
the Southwest and central California. A few strong thunderstorms may
occur across parts of Missouri and southern Illinois late tonight,
but organized severe thunderstorm potential appears low.
...Synopsis...
A pair of upper troughs/lows will impact the CONUS today. The
leading upper trough/low will progress eastward over the central
Plains though this evening, eventually reaching the mid MS Valley
late tonight. Farther west, a separate upper trough/low will develop
slowly southward across coastal CA through the period. With
seasonably cool temperatures and modestly steepened lapse rates
aloft associated with the western U.S. trough/low, isolated
thunderstorms may occur across parts of CA and the lower CO River
Valley/AZ. Meager instability across these areas should limit the
threat for organized severe thunderstorms. Father east, isolated to
scattered thunderstorms should develop this evening/overnight from
portions of the northern/central Plains into the MO and mid MS
Valleys. The bulk of this activity is expected to remain elevated,
with minimal severe potential.
...Ozarks into the Mid Mississippi Valley...
Low-level moisture will continue to stream northward across the
southern Plains and lower/mid MS Valley ahead of a weak surface low
and cold front related to the lead upper trough/low. Latest NAM/RAP
forecast soundings across the surface warm sector this
afternoon/evening continue to show a substantial cap in place, which
combined with negligible large-scale ascent should act to inhibit
surface-based convective development. Low-level warm/moist advection
is expected to increase this evening/overnight as a southwesterly
low-level jet strengthens over the Ozarks/mid MS Valley. Most
guidance shows weak MUCAPE (around 500-1000 J/kg) with modest
mid-level lapse rates present. This should tend to limit the updraft
strength of scattered elevated convection that is forecast develop
tonight across MO into parts of southern IL, even in the presence of
moderate to strong deep-layer shear. While small/sub-severe hail may
occur with the stronger cores, the threat for severe hail appears
too limited to include low probabilities with this update.
..Gleason/Broyles.. 11/17/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0307 AM CST Mon Nov 17 2025
Valid 201200Z - 251200Z
...DISCUSSION...
...Day 4/Thursday - Southern Plains to Mid-MS Valley...
An upper trough over the Four Corners vicinity will eject
east/northeast into the Plains on Thursday. Moderate southwesterly
deep-layer flow will overspread portions of OK/TX toward the Ozarks
as this occurs. Warm advection ahead of the trough, coincident with
a weakening southerly low-level jet, will result in widespread
showers and thunderstorms across the region early Thursday. This may
temper destabilization despite rich boundary layer moisture.
Meanwhile, a surface low will modestly deepen near the OK/KS border,
and a north-south oriented cold front draped across west TX will
develop eastward through the period, with a warm front extending
west-east across central MO/southern IL. These boundaries may focus
some risk for stronger storms within a weak to moderately unstable
airmass. However, the magnitude of the severe risk still remains
uncertain given potential for widespread and possibly heavy
rainfall, somewhat weak low-level flow, and the weakening of the
upper trough as it shifts east/northeast during the evening. Severe
probabilities may become necessary is subsequent outlooks, but
uncertainty remains too high to include a 15 percent delineation at
this time.
...Day 5/Fri - Mid/Lower MS and OH/TN Valley vicinity...
The surface cold front will continue to develop east/southeast
across the region on Friday/Friday night. Some low-end severe
potential could persist given rich boundary layer moisture and at
least modest buoyancy ahead of the front. However, persistent
rainfall and a weakening upper trough with veering/boundary-parallel
deep-layer flow will likely limit storm intensity.
...Days 6-8/Sat-Mon...
Spread among forecast guidance increases late in the period and
forecast confidence is low. However, most guidance depicts some
version of an upper trough/low over the Southwest ejecting east
toward the Plains, but the differences in timing/intensity, etc
limit predictability. Some increase in severe potential could return
to portions of the southern Plains depending on how this potential
trough evolves and guidance trends will be monitored.
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