RSS Mesoscale Discussions from Storm Prediction Center
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0652 PM CST Wed Dec 31 2025
Valid 010100Z - 011200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms may occur across parts of southern California
late tonight.
...01z Update...
Well-defined upper low is lifting northeast toward the southern CA
coast as a 500mb speed max translates into the base of the trough,
but remaining offshore. Left exit region of this jet will encourage
convection along the weak front as it surges toward the coast late
tonight. Primary concern for lightning will be after 09z, but this
activity will be elevated and within a poor instability environment.
Severe risk appears minimal tonight.
..Darrow.. 01/01/2026
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SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 PM CST Wed Dec 31 2025
Valid 011200Z - 021200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF SOUTHERN COASTAL CALIFORNIA...
...SUMMARY...
Locally damaging winds, and a perhaps a brief weak tornado, could
occur along a portion of coastal southern California.
...Southern CA...
Latest water-vapor imagery depicts a well-defined upper low about
300 mi WSW of Lompoc CA ejecting ENE in line with latest model
guidance. This feature is forecast to shift inland as a 500mb speed
max translates across the Channel Islands toward southern NV by
early evening. Left-exit region of this jet will overspread the
southern interior valley with seasonally cool 500mb temperatures
noted north of the jet. Even so, forecast instability is expected to
remain weak as MUCAPE values should remain generally less than a few
hundred J/kg. Midlevel lapse rates are also not expected to be
particularly steep and this is reflected in the sparsity of
lightning currently noted with convection beneath the offshore low.
Latest thinking is scattered weak convection will be the primary
concern with the frontal zone early in the period, and much of this
activity may struggle to generate lightning despite the maritime
influences that will prove instrumental for this activity. While
some risk for gusty winds, and perhaps a brief weak tornado exists,
the majority of convection will remain sub severe.
..Darrow/Squitieri.. 01/01/2026
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