RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 PM CST Sun Dec 28 2025
Valid 291200Z - 301200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
A few thunderstorms may be noted across the lower Rio Grande Valley
very early in the period.
...Lower Rio Grande Valley...
Surface front is surging south across south central TX late this
evening as pressures build over the central/southern Plains. Latest
model guidance suggests the wind shift will reach the international
border around 12z, then quickly advance deep into northeast Mexico.
A narrow band of shallow convection is currently noted along the
front as far west as Wilson county TX. Forecast soundings for deep
South TX at the start of the period suggest both pre frontal and
post frontal parcels will exhibit sufficient buoyancy for the
strongest updrafts to possibly penetrate levels necessary for
lightning discharge. Any post frontal lightning threat should be
over by 15z.
..Darrow/Squitieri.. 12/29/2025
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SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 PM CST Sun Dec 28 2025
Valid 301200Z - 311200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms will not occur on Tuesday or Tuesday night.
...Discussion...
Conditions will be too dry/stable for lightning-producing convection
across the CONUS through the period.
..Grams.. 12/29/2025
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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CST Mon Dec 29 2025
Valid 311200Z - 011200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are possible late Wednesday night/early
Thursday morning along coastal southern California.
...Southern CA...
A retrograding cutoff low currently near the central/southern CA
coast is consistently progged to eject back northeastward as a
shortwave trough towards the southern CA coast on Wednesday night.
Ahead of this trough, sufficient 850-700 mb moisture within the
modest warm conveyor combined with weak mid-level cooling may yield
scant elevated buoyancy by the 06-12Z period. This could support a
threat of isolated thunderstorms, mainly early morning Thursday.
..Grams.. 12/29/2025
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