898 
ACUS03 KWNS 181913
SWODY3
SPC AC 181912

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0112 PM CST Thu Dec 18 2025

Valid 201200Z - 211200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible across western Oregon and
northern California late Saturday night.

...Synopsis...
A broad cyclonic flow regime aloft will develop from the central
into the eastern CONUS on Saturday, with an upper trough amplifying
from the northern Plains into the Great Lakes. Gradual height rises
will occur over the West, with weak flow aloft across the southern
tier of states. Late in the period into Sunday morning, height falls
will begin across the Pacific Northwest with an approaching wave.

At the surface, high pressure will exist along the East Coast with
southerly winds across the western Gulf and into the southern
Plains. While some degree of low-level moisture return will occur,
another cold front will push south across the Plains behind the
developing Great Lakes system. As a result, any instability over
coastal TX/LA should remain capped.

Chances for thunderstorms will develop late in the period across the
Pacific Northwest as a plume of midlevel moisture arrives out of the
west. This moistening and warming in the 850-700 mb layer will
result in weak elevated instability sufficient for isolated
lightning.

..Jewell.. 12/18/2025

$$