Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
150 PM EST Sun Dec 11 2022

Valid 00Z Mon Dec 12 2022 - 00Z Wed Dec 14 2022

...Major storm system currently bringing heavy mountain snow and coastal
rain to the West will begin to shift into the Plains Monday...

...Wintry precipitation for the Interior Northeast tonight with some snow
accumulations expected...

...Episodes of moderate to heavy rainfall possible as showers and
thunderstorms continue for the South...

Heavy mountain snow and coastal rain will continue in the West tonight
under the influence of a deepening upper-level trough and strong surge of
moisture overspreading the region from the Pacific. Additional snowfall
totals generally between 6-12 inches, locally higher, are possible through
Monday for the mountains of the Great Basin, Central Rockies, Arizona, and
southern California. Avalanche Warnings are in effect for portions of
central-southern Idaho. While most of the significant snow should remain
at higher mountain elevations, some light accumulations are possible in
the interior valleys, particularly in the northern Great Basin. Heavy
coastal rainfall intensified by the strong surge of moisture from the
Pacific associated with an atmospheric river will shift from the central
California coast to southern California tonight. There is a Slight Risk of
Excessive Rainfall in effect for the Transverse and Peninsular Ranges of
southern California where locally high totals of 2-3+ inches may result in
scattered instances of flash flooding, particularly in the vicinity of
burn scars and urbanized areas. In addition to the heavy snow and rain,
strong winds will also continue to be a concern. Wind Advisories remain in
effect for portions of the central and southern Great Basin and California
where gusts running higher than 45 mph remain possible. High temperatures
will stay 10-20 degrees below average beneath the upper-level trough.

A strong surface low will begin to develop in the lee of the Rockies early
Monday as the upper-level trough continues eastward. Moisture will begin
surging northward over the Plains following a developing warm front and
ahead of a developing cold front. The anomalously high moisture return
ahead of the developing surface fronts as well as the strong system
dynamics will help to initiate widespread showers and thunderstorms. There
are Marginal Risks of Excessive Rainfall and Severe Thunderstorms on
Monday for portions of the Central/Southern Plains where intense downpours
may accompany some of the storms. To the north, Winter Storm Watches are
in effect for portions of the Northern/Central Plains and Upper Midwest as
snow and freezing rain will begin to ramp up late Monday evening. While
most of the impacts from this storm are still outside of the current
forecast period, the expectation is for widespread heavy snow with the
potential for blizzard conditions and accumulating freezing rain so
interests should continue to monitor the latest forecasts. Generally
between 6-12 inches of snow with locally higher amounts are currently
expected for portions of the Front Range through central South Dakota and
northwestern Nebraska on Tuesday. Strong downslope winds ahead of the
system will lead to highs of 10-20 degrees above average for portions of
the High Plains, with 50s and 60s expected more broadly across the Central
and Southern Plains. These warm and windy conditions will support an
Elevated Fire Weather threat over parts of eastern Colorado through Monday
where Red Flag Warnings are in effect. Much colder temperatures in the
teens and 20s will begin spreading southward through the Northern Plains
Monday.

An upper-level wave moving quickly over the Northeast with an accompanying
front at the surface will bring the chance for rain and wintry
precipitation on through tonight. Additional snow accumulations of 1-3
inches, locally higher, are forecast for parts of southern New England.
While locations in the Mid-Atlantic closer to the coast should see mostly
rain, some snow may mix in later tonight. High temperatures are expected
to remain a bit cooler than average with highs in the 20s and 30s for New
England, 30s and 40s for the Mid-Atlantic, and 50s in the Carolinas.

Small-scale disturbances moving along a frontal boundary slowly drifting
southward across the South will continue to help initiate rounds of
showers and thunderstorms late this afternoon and early evening producing
areas of moderate to heavy rainfall. There is a Marginal Risk of Excessive
Rainfall for portions of the Texas and Louisiana Gulf Coasts into
southwestern Mississippi where storms moving roughly parallel to the front
may lead to locally heavier rainfall totals and an isolated instance or
two of flash flooding. Temperatures north of the front will be a bit
cooler than they have been recently with highs in the 60s to low 70s.

Putnam/Kebede

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