Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
250 PM EST Fri Dec 09 2022

Valid 00Z Sat Dec 10 2022 - 00Z Mon Dec 12 2022

...Major storm system to bring heavy mountain snow and coastal rain to the
West this weekend...

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

...Wintry weather expected to enter the Northeast early Sunday...

A deep upper-level trough and closed low entering the West tonight will
usher in a surge of Pacific moisture that will produce dangerous winter
weather conditions across the high terrain, as well as heavy rain along
coastal California. Heavy mountain snow is expected to first enter the
Cascades, Sierra, and northern Great Basin this weekend. Heavy snowfall
rates will likely result in extremely dangerous travel, especially across
mountain passes. Snowfall totals of 1-3 feet are possible across much much
of the higher terrain, with locally more than 5 feet expected in the
Sierra. Winter Storm Warnings and Winter Weather Advisories are in effect
from the southern Sierra Nevada to the northern Cascades. Gusty winds may
also accompany the system, which has prompted High Wind Warnings and Wind
Advisories to be hoisted over parts of California and southwest Oregon. At
the lower elevations, heavy rain is possible along a cold front as it
gradually pushes inland and southward across California through Sunday.
Rainfall amounts of 2 to 4 inches may lead to scattered instances of flash
flooding across the central coast of California on Saturday and southern
California on Sunday. Recent burn scars and susceptible terrain will be
most at risk to flooding and rapid runoff. A Slight Risk (level 2 of 4)
for flash flooding has been issued for these regions. Hazardous snowfall
is also anticipated to enter the Intermountain West on Sunday and Sunday
night, with snow even reaching into the lower elevations.

Farther east, a lingering frontal boundary extending from the southern
Plains to the Southeast may produce areas of heavy rain from north-central
Texas to Arkansas on Saturday. General rainfall totals should not lead to
widespread flash flooding concerns, but isolated impacts cannot be ruled
out where the heaviest rates occur. This area of showers and thunderstorms
is forecast to shift eastward on Sunday before the system over the western
U.S. enters the Great Plains early next week.

For the Northeast, a relatively weak upper-level low swinging from the
Great Lakes will lead to an area of light to moderate snowfall across
parts of the Northeast on Sunday. The areas most likely to see a coating
to a few inches of snow extends from Upstate New York and northern
Pennsylvania to far southern New England. This may lead to a brief period
of slippery travel Sunday that could linger into the early morning hours
on Monday.

Temperatures for much of the central and southern United States this
weekend will reach into above average territory, with the most anomalous
warmth centered across the Deep South and Gulf Coast. Otherwise, chilly
weather will remain over parts of the Mid-Atlantic, Northeast, and West.

Snell


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