Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
333 PM EST Tue Dec 23 2025

Valid 00Z Wed Dec 24 2025 - 00Z Fri Dec 26 2025

...Strong atmospheric river brings heavy rain, snow, and wind to
California through Friday...

...Moderate to heavy snow continues over New England today; freezing rain
possible along the Northern Tier Thursday...

...Unseasonable warmth forecast for much of the Lower 48 through Christmas
Day...

Across the Lower 48, much of our weather pattern remains dominated by an
anomalous upper-ridge anchored over the Nation's Heartland and a highly
amplified trough upstream over the Eastern Pacific. This configuration is
expected to persist through the end of the work week, in turn supporting
dangerous atmospheric river conditions across California through Friday.
To address the heavy rainfall forecast first, the threat of particularly
heavy rainfall is expected to increase over Southern California (including
the Los Angeles metro) late tonight ahead of a deepening low pressure
wave. By tomorrow morning, a rare High Risk of Excessive Rainfall is in
effect for Southern California, where widespread 4-7" rainfall totals
(locally upwards of 9") is expected over an 18 hour time period. Remember,
WPC High Risk days are a BIG DEAL: 80% of all flood related damages and
30% of all flood related fatalities occur in High Risk areas. Users in
these areas are encouraged to remain vigilant as landslides, rockfalls,
and mudslides are also anticipated over portions of the Transverse Range.
Outside of the High Risk, surrounding areas in Central/Northern California
(including San Francisco and San Diego) and southern Nevada (including Las
Vegas) can also expect scattered flash flooding through Friday. In the
mountains of the Sierra Nevada, snowfall will be measured in feet as
prolonged heavy snowfall increases tonight and snow levels fall following
a frontal passage. Accordingly, travel through mountain passes will
quickly become impossible as blowing snow begins to pile up. Impactful
wind is also expected in neighboring coastal and mountain areas, which
will drive widespread power outages and tree damage.

On the opposite coast, moderate to heavy snowfall is expected to
overspread New England tonight ahead of an occluded low pressure system.
Moderate to locally major winter storm impacts are possible with this
event over portions of coastal Maine tonight, where 6-12 inches of snow is
in the forecast. Adjacent areas in the Adirondacks and Greens can expect
3-7" through Christmas Eve, where a handful of Winter Weather Advisories
are in effect. Freezing rain is a concern across portions of the Northern
Tier on Christmas Eve and Christmas as moisture from the California
atmospheric river interacts with an approaching shallow Arctic airmass,
with upwards of a tenth of an inch possible. Temperature wise, the strong
upper-ridge means much of the Lower 48 can expect a very mild Christmas
with temperatures in the 70's and even low 80's forecast over the Southern
and Central U.S. Much of the sub-freezing temperatures will be relegated
to the Northern Tier, where the aforementioned freezing rain is possible.
Even so, for this time of year, those temperatures are 10-15 degrees above
average.

Asherman


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