Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
349 PM EDT Mon Mar 20 2023

Valid 00Z Tue Mar 21 2023 - 00Z Thu Mar 23 2023

...Powerful storm system to spread high winds, heavy rain, and heavy
mountain snow to parts of California and the Southwest on Tuesday...

...Threat of heavy snow continues across the Intermountain West and
Rockies over the next few days...

...A couple rounds of light-to-moderate snowfall are expected across
portions of the northern Plains and Upper Midwest between Tuesday and
Thursday morning...

The most impactful weather system to affect the U.S. through midweek is
forecast to move across California and the Southwest on Tuesday. A rapidly
strengthening low pressure system to deepen off the West Coast will swing
toward the central California coast and produce potentially damaging wind
gusts, heavy rain, and heavy mountain snow. The strong pressure gradient
associated with the anomalously low pressure could lead to maximum wind
gusts near 75 mph across Southern California, with gusts up to 50 mph
across central California. Additionally, a surge of subtropical moisture
will accompany this system and create a ripe environment for heavy rain
from the central coastline to Southern California. Heavy rain is likely to
lead to rapid runoff and areas of flooding across southern California,
with isolated flooding instances possible for regions to the north. For
the mountainous terrain of the southern/central Sierra Nevada and Southern
California, heavy snow will be the primary hazard as snowfall
accumulations add up to as much as 3 to 4 feet in spots. This additional
snowfall will lead to difficult travel and could strain infrastructure in
areas still buried under a record-breaking snowpack for the year-to-date.
Impacts are also anticipated to spread farther inland during the second
half of Tuesday across the Southwest, central Great Basin, and
south/central Rockies. Gusty southwesterly winds up to 60 mph are possible
across the Desert Southwest, with heavy rain and localized flash flooding
possible across parts of central Arizona. Elevated terrain from central
Nevada to western Colorado can expect heavy snow to last into Wednesday.
Dangerous to difficult travel is likely, with most mountain ranges
experiencing over a foot of snowfall. Numerous wind, flood, and winter
headlines have been issued for the upcoming storm. Be sure to check with
your local forecast office for details.

Wintry weather will also impact the north-central U.S. through early
Thursday as two separate systems traverse the region. Between Tuesday and
Wednesday morning, a low pressure system is forecast to swing from the
northern Plains to the Upper Great Lakes, with locally heavy snow possible
just to the north from southeast North Dakota to northern Minnesota.
Snowfall amounts up to 7 inches are possible and when combined with areas
of blowing snow, visibility could be reduced and create treacherous
driving conditions. The next system to impact the central U.S. is expected
to swing eastward late-Wednesday and produce the potential for a swath of
additional snowfall from south Dakota to southern Minnesota (so just to
the south of the first storm). Snowfall totals could add up to over 4
inches. Farther south and east, scattered showers and thunderstorms are
anticipated to develop along a stationary front Wednesday night across
portions of the Midwest.

Elsewhere, one more chilly morning is on the way for the Southeast on
Tuesday before springlike temperatures migrate eastward from the southern
Plains by midweek. Low temperatures tonight are still likely to dip below
freezing throughout the Tennessee Valley and Southeast. Freeze Warnings
and Frost Advisories have been issued from eastern Mississippi to the
Carolinas in order to highlight the potential for damage to sensitive
vegetation and unprotected outdoor plumbing.

Snell


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