Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0653 AM CST Sun Dec 21 2025

Valid 211300Z - 221200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Discussion...
A progressive/zonal upper-flow pattern will continue over the CONUS.
A low-amplitude shortwave trough will move inland across the Pacific
Northwest by tonight. Weak buoyancy and cooling temperatures aloft
may become sufficient for isolated lightning flashes, particularly
near the Washington coast. Farther south, a moisture-rich plume and
a marginally favorable thermodynamic environment may allow for some
lighting flashes across northern California.

Elsewhere, a relatively moist airmass near/south of a
southward-moving front, along with continued weak warm/moist
advection, will probably be conducive for isolated thunderstorms
mainly across southern portions of Louisiana and Mississippi today.

..Guyer/Marsh.. 12/21/2025

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0957 AM CST Sun Dec 21 2025

Valid 211630Z - 221200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

Thunderstorm potential will be limited across the CONUS.  Strong
onshore flow and cold temperatures aloft will pose a risk of a few
lightning flashes today and tonight over portions of the WA/OR coast
and parts of northern CA.  Low-level warm advection and an
approaching cold front could result in isolated thunderstorms this
afternoon over parts of southern LA/MS, and late tonight over south
TX.  No severe storms are anticipated today.

..Hart/Karstens.. 12/21/2025

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1046 AM CST Sun Dec 21 2025

Valid 221200Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast on Monday.

...Synopsis and Discussion...
Minimal thunderstorm potential remains evident across much of the
CONUS on Monday, as upper-level ridging is maintained over the
central U.S. One exception may be across parts of coastal WA/OR as a
mid-level shortwave trough progresses eastward from the eastern
Pacific into British Columbia and the Pacific Northwest through
Monday afternoon/evening. Even though daytime heating and low-level
moisture are forecast to remain limited, cool temperatures aloft and
weak MUCAPE associated with the shortwave trough may support
occasional lightning flashes with low-topped convection moving
inland along the immediate WA/OR Coast.

A plume of mid-level moisture and associated precipitation will
impact parts of northern/central CA through the period, although
warmer mid-level temperatures compared to locations farther north
and negligible forecast instability suggest little potential for
lightning. Elsewhere, very weak forcing aloft should limit
thunderstorm potential across coastal TX to the central Gulf Coast,
even as low-level moisture gradually increases across these areas.

..Gleason.. 12/21/2025