Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
226 AM EST Sun Dec 21 2025

Valid 12Z Sun Dec 21 2025 - 12Z Tue Dec 23 2025

..There is a Moderate Risk of excessive rainfall over parts of Northern
California on Sunday and Monday...

...Heavy snow downwind from Lake Ontario...

...Rain/freezing rain possible over the Northern Plains and Pennsylvania...

A front extending along the Northeast and Mid-Atlantic States swings
southwestward to the Central Gulf Coast States and the Southern Plains,
and moves eastward off the Northeast and Mid-Atlantic Coast by Sunday
afternoon. Moisture flowing northward from the Gulf will overrun the
boundary over the Central Gulf Coast Area, producing rain over the region
through Monday morning. Moreover, upper-level energy moving over the Great
Lakes to the Northeast will produce lake-effect snow downwind from the
Great Lakes through early Monday morning. Heavy snow will develop downwind
from Lake Ontario through Monday evening.

Meanwhile, disorganized upper-level energy moving over the Upper Midwest
will trigger light snow over the Upper Mississippi Valley into the Great
Lakes early Monday morning that will expand into the Northeast by Monday
evening into Tuesday. Along the rain/snow line in Pennsylvania, areas of
rain/freezing rain will develop over the region Monday night into Tuesday
morning.

Furthermore, rain will develop over parts of the Tennessee/Ohio Valleys by
Monday evening, expanding into parts of the Mid-Atlantic by Tuesday.
Moreover, there will be a chance of rain/freezing rain over parts of the
Northern Plains on Monday into Tuesday morning. 

In the meantime, moisture from the Pacific will stream eastward over the
Pacific Northwest/Northern California, producing rain over the Northwest,
Northern/Central California, and the Great Basin. The flow off the ocean
will produce heavy rain over parts of Northern California. Therefore, the
WPC has issued a Moderate Risk (level 3/4) of excessive rainfall over
parts of Northern California from Sunday into Tuesday morning. Numerous
flash flooding events are possible. In addition, many streams may flood,
potentially affecting larger rivers. The flooding may include debris flows
in or near recently burned areas. Snow will also develop over the highest
elevations of the Sierra-Nevada Mountains, the Cascades, the Northern
Intermountain Region, and the Northern Rockies on Sunday and Monday.


Ziegenfelder


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php