Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Fri Feb 24 2023

Valid 12Z Fri Feb 24 2023 - 12Z Sun Feb 26 2023

...An unusually cold and slow-moving winter storm to bring very heavy
snowfall and strong winds to California and adjacent areas of the West
through Saturday...

...Heavy rainfall and flooding will be possible for parts of southern
California...

...Heavy snow possible for Northwest mountains later this weekend...

...Temperatures to remain above normal in the East this weekend...

The prolonged winter storm that yielded significant impacts from the West
through the Midwest and into the Great Lakes region with heavy snow,
strong winds and ice over the last few days is gradually winding down.
Gusty winds may create areas of blowing and drifting snow. In the wake of
this winter storm frigid temperatures, currently over the upper Midwest,
will move east across the Great Lakes and into the Northeast today. The
cold temperatures will not be quite as extreme as they have been in recent
days, but expect temperatures to drop well below normal, with overnight
lows locally dropping below zero. Milder air should begin to arrive by
later in the weekend with temperatures eventually warming to near or above
normal.

Meanwhile, very active winter weather will continue across areas of the
West through the end of the week and the start of the weekend as a very
cold and slow-moving storm system drops south down along the West Coast
and gradually pivots into the Southwest this weekend. For today,
California in particular will be the dominant focus for the greatest
winter storm impacts. Multiple rounds of heavy snowfall coupled with
strong winds will lead to blizzard conditions over some of the higher
terrain and mountain passes, including the central and southern Sierra
Nevada, and the high terrain of Transverse Range in southern California.
This may lead to downed trees and power lines which will contribute to
power outage concerns. This storm system will be unusually cold, and snow
levels will be very low. In fact, areas very close to the Pacific Coast
and also into the interior valleys that are not accustomed to seeing snow,
may see some accumulating snowfall. Snowfall should accumulate to as much
as 3 to 5 feet for the Sierra Nevada, with locally heavier totals for the
highest peaks. Lesser amounts of 1 to 2 feet are forecast elsewhere across
portions of the Great Basin and into the Four Corners region as the storm
begins to pivot into the Southwest by Sunday.

While heavy snow and strong winds will tend to dominate the headlines for
this winter storm, one other major concern will be the threat of heavy
rainfall and flooding for some of the immediate coastal ranges of southern
California below the snow level. Several inches of rain are expected
locally, and this will drive locally significant runoff concerns. In fact,
the Weather Prediction Center has depicted a Moderate Risk of excessive
rainfall for portions of the Transverse Range.

Another system will arrive over the Pacific Northwest late Saturday night
into Sunday, bringing with it another round of Pacific moisture. Moderate
to heavy snow may develop over portions of the Cascades and Northern
Rockies. The northern Cascades will likely receive the brunt of the
precipitation; 1-2 feet of snow are possible by Monday morning. Troughing
along the Upper Great Lakes and a cold airmass will likely produce some
light Lake Effect snow for the region tonight. Showers and thunderstorms
may develop along a quasi stationary boundary draped across the Southeast
this weekend. Additionally, a coastal low may develop and generate some
light wintry precipitation across portions of the Mid-Atlantic Coast on
Saturday.

Elsewhere, the record-warm temperatures seen across much of the East will
be tempered by the passage of a cold front through today, but many areas
of the Mid-South, Southeast, and Gulf Coast will continue to see above
normal temperatures heading through the weekend.

Kebede/Orrison

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