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

Valid 00Z Mon Dec 22 2025 - 00Z Wed Dec 24 2025

...A highly impactful Atmospheric River event for Christmas week across
California...

...Much above average temperatures to stretch across large sections of the
Lower 48, with record highs likely from the Southwest into the Central to
Southern Plains...

A very wet weather pattern will continue along large portions of the West
as the Christmas week travel rush begins.  A persistent, stronger than
average onshore flow of very moist Pacific air will bring rounds of rain
into the West from the Pacific Northwest, southward into Northern
California.  The heaviest rainfall amounts expected across Northern
California Monday and Tuesday where totals of 3 to 5 inches are likely
across the Northern Sierra and 1 to 3 inches along coastal regions from
San Francisco, northward.  Snow levels are expected to remain higher than
average, with much of the precip impacting northern California falling as
rain. While soil moisture is starting out relatively dry across all of
California, the potential for several days of heavy rains will lead to
increases chances of flooding, along with increasing potential for
landslides, rock falls and mudslides as the rainfall totals add up.  By
late Tuesday into Wednesday, the heavy rain and flooding threat will begin
to also push southward into central to southern California as a storm
system begins to strengthen off the California coast and move
north-eastward.  At the same time, another surge of heavy precipitation
will impact northern California, along with continued flooding, landslide,
rock fall and mudslide threats.  This wet weather pattern shows no signs
of letting up, with another round of heavy precipitation possible
Christmas day into Friday for much of California.  By the time the holiday
week ends, widespread precipitation totals of 5 to 10 inches possible
across much of California, with maximum totals of 10 to 20 inches expected
across the Northern Sierra.

A relatively drier weather pattern on tap for the remainder of the Lower
48 this week.  A quick moving area of low pressure moving across southern
Canada will produce generally light to moderate precipitation amounts from
the Great Lakes into the Northeast/New England Monday through Wednesday. 
Accumulating snows are possible across western to Upstate New York,
western and northern portions of New England.

The very wet weather pattern affecting the West coast this week will also
support much above average temperatures across much of the Lower 48.  The
mid to upper level flow will remain primarily out of the west across the
central to eastern U.S. and out of the southwest along the West coast. 
This will keep arctic air out of the Lower 48, with it remaining north of
the border across Canada and Alaska.  There is potential for record high
temperatures Monday and Tuesday from the Southwest, across the southern
Great Basin, Central to Southern Rockies and into the Central to Southern
High Plains.  Across these regions, high temperatures are forecast to be
15 to 35 degrees above average.   This much above average to record high
temperature pattern will persist into Christmas, limiting any chances of a
white Christmas, defined by 1 inch or more of snow on the ground,  to
areas of Northern New England, northern to western NY State, the Upper
Great Lakes, the Upper Mississippi Valley, Northern Rockies and northern
Cascades.

Oravec


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