RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0625 AM CST Wed Dec 31 2025
Valid 311300Z - 011200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are possible along coastal southern
California very late in the period.
...Southern CA...
A southern-stream upper-level trough will approach the southern CA
coast late tonight. Latest model guidance suggests increasing
large-scale ascent will approach the coast, contributing to isolated
convection along/ahead of a weak front as it surges inland,
primarily after 09z. Forecast soundings along the coast suggest
thunderstorms should be elevated in nature, with initial convection
likely rooted at or above 850mb. Weak buoyancy and shear suggests
minimal potential for severe storms prior to 12z Thursday.
..Bunting/Weinman.. 12/31/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CST Wed Dec 31 2025
Valid 031200Z - 081200Z
...DISCUSSION...
Primary severe concern will be across the northeast Gulf Coast
States, during the morning to afternoon on D4/Saturday. A
lower-amplitude shortwave trough remains consistently progged to
dampen as it progresses quickly across the Southeast and northeast
Gulf. With a weak surface cyclone, low-level winds should remain
veered. But this should be adequate for weak buoyancy to spread
east, emanating from the northwest Gulf and LA. With a more robust
convective signal closer to the coast compared to D3/Friday, at
least a level 1-MRGL risk should be warranted. This is supported by
latest SPC-CSU and NSSL GEFS-based ML guidance with overlapping 5
percent probability areas.
Along coastal CA, while run-to-run predictability is poor, latest
guidance has some signal for low-topped supercell potential this
weekend, downstream of a large-scale trough off the Pacific Coast.
This appears generally focused across northern CA on D4/Saturday,
shifting to southern CA on D5/Sunday. Spatiotemporal aspects of
individual shortwave impulses and attendant mid-level jetlets
relative to probable scant/meager buoyancy profiles will be crucial
for delineating areal highlights in shorter-term outlooks.
Otherwise, a combination of low potential/predictability remains
evident early next week.
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