572 
FXUS01 KWBC 220735
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
234 AM EST Mon Dec 22 2025

Valid 12Z Mon Dec 22 2025 - 12Z Wed Dec 24 2025

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

...Heavy snow downwind from Lake Ontario and New England...

...Rain/freezing rain possible over the Pennsylvania and Central
Appalachians...

A wave of low pressure over the Northern Rockies will move
eastward toward the Great Lakes by Tuesday morning, and then merge
with low pressure from Eastern Canada by Tuesday evening. By
Wednesday morning, the low will move off the eastern seaboard,
trailing a front from the Southeast to the Northern Rockies.
Disorganized upper-level energy moving over the Upper Midwest will
trigger light snow over the Upper Mississippi Valley/Great Lakes
early Monday morning that will move into the Lower Great Lakes by
Monday evening. On Tuesday, snow will develop over parts of the
Northeast.

Along the rain/snow line in Pennsylvania and the Central
Appalachians, areas of rain/freezing rain will develop over the
region Monday night into Tuesday. Overnight Tuesday, the
rain/freezing rain will move into parts of Southern New England
while snow develops over parts of Northern New England and Eastern
New York State.

Moisture flowing northward from the Gulf will overrun the boundary
over the Central Gulf Coast Area, producing rain over the region
through Monday Afternoon. Overnight Monday, rain will develop over
the Ohio Valley and expand into the Mid-Atlantic and Tennessee
Valley by Tuesday morning. However, by Tuesday evening, the rain
will retreat to the Tennessee Valley.

Meanwhile, upper-level impulses and 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. On Monday, the flow from 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 through 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 Monday and Tuesday.

On Tuesday, a broad plume of moisture will move over California,
with rain moving into Southern California and the Great Basin
overnight. Two areas of heavy rain will develop over
Northern/Central California and over Southern California.
Therefore, the WPC has issued a Slight Risk (level 2/4) of
excessive rainfall over parts of Northern/Central California from
Tuesday into Wednesday morning. The associated heavy rain will
create mainly localized areas of flash flooding, with urban areas,
roads, small streams, and burn scars being the most vulnerable.

Similarly, a second area of heavy rain will develop over parts of
Southern California on Tuesday. Therefore, the WPC has issued a
Slight Risk (level 2/4) of excessive rainfall over parts of
Southern California from Tuesday into Wednesday morning. The
associated heavy rain will create mainly localized areas of flash
flooding, with urban areas, roads, small streams, and burn scars
being the most vulnerable.


Ziegenfelder


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

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