Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
353 PM EDT Tue Mar 21 2023

Valid 00Z Wed Mar 22 2023 - 00Z Fri Mar 24 2023

...Powerful storm system to spread high winds, heavy rain, and heavy
mountain snow into portions of California and the Southwest...

...Widespread rain and heavy mountain snow expected to move across the
Southwest, Great Basin, and the central and southern Rockies by early
Thursday...

...Heavy snowfall to impact portions of the Northern Plains and Upper
Mississippi Valley through midweek...

A very strong low pressure system currently just offshore of San Francisco
Bay will continue to bring high winds, heavy rain, and heavy mountain snow
for California and adjacent areas of the Southwest through tonight and
Wednesday as the latest in a series of atmospheric rivers impacts the
West. The low pressure system will advance across the Intermountain West
going through the middle of the week, and this will bring heavy snowfall
across large areas of the Great Basin and into the higher terrain of the
central and southern Rockies going through early Thursday.

Regarding the impacts from this storm system, the winds this evening
across areas of central and southern California will be quite strong and
may reach as high as 60 to 70 mph with higher gusts. This coupled with the
heavy rainfall may lead to downed trees and power lines. Locally several
inches of rainfall is expected by Wednesday morning across especially
southern California and this will foster concerns for rapid runoff,
flooding and mudslides given the already wet, saturated soil conditions
that are in place. The snowfall will be quite heavy once again for the
central and southern Sierra Nevada as the system moves inland, and
additional snowfall amounts of 3 to 4 feet can be expected with isolated
heavier amounts. This additional snowfall will lead to difficult travel
and could strain infrastructure in areas already buried under a
record-breaking snowpack for the year-to-date.

Impacts are also anticipated across the Southwest, central Great Basin,
and gradually reaching into the central and southern 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 through Wednesday before then tapering down
by early Thursday. Dangerous to difficult travel is likely here, with most
mountain ranges expected to see as much as 1 to 2 feet of additional
snowfall with isolated heavier amounts.

Wintry weather will also impact the north-central U.S. through midweek as
a storm system traverses the region. Low pressure currently strengthening
over the northern Plains will advance across the Upper Mississippi Valley
by Wednesday morning, and this should interact with sufficient cold air
for a swath of heavy accumulating snow for eastern North Dakota and much
of northern Minnesota. As much as 6 to 10 inches of snow, with isolated
amounts in excess of 1 foot will be possible before the snow tapers off.
This storm system will pull away from the region and exit into Ontario on
Thursday.

On Thursday, aside from very warm and much above normal temperatures
overspreading much of the South and large sections of the eastern U.S.,
there will be a growing concerns for developing showers and thunderstorms
later in the day across central and eastern Oklahoma into southwest and
central Missouri as a strong front gradually stalls out across the region.

Orrison


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