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

Valid 12Z Fri Dec 09 2022 - 12Z Sun Dec 11 2022

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

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

...Wintry weather expected for the Upper Midwest Friday and Saturday
before moving into the Northeast early Sunday...

Snow showers will continue over the Northern and Central Rockies during
the day Friday as an upper-level shortwave quickly moves over the region
before a major storm system approaches the West Coast Friday evening.
Widespread heavy precipitation will begin to overspread the Northwest and
northern California during the day Friday and further into the Northern
Rockies, Great Basin, and the rest of California Saturday. Anomalously
high moisture associated with an Atmospheric River will promote heavy
mountain snow as well as heavy rain with showers and thunderstorms for
lower elevations along the coast. Numerous winter-weather related
advisories are in effect for the mountains as well as some of the interior
valleys in the Pacific Northwest, Northern Rockies, and northern Great
Basin. Snow totals will generally range between 6-12 inches, locally
higher, for the higher elevations with lighter accumulations between 1-3
inches for the interior valleys. The highest snow totals are currently
expected for the Sierra Nevada in California where several feet of snow is
forecast. There is a Marginal Risk of Excessive Rainfall along the coast
for southern Oregon and northern California Friday and along most of the
California coast on Saturday. Rainfall totals locally as high as 3-4
inches, with hourly rates over 0.5 inches, may lead to a couple instances
of flooding.

Moderate to heavy rain will continue across the South into the weekend as
disturbances along a wavy stationary boundary trigger more showers and
thunderstorms. The axis of heaviest rainfall will depend on the location
of the front, and is currently expected to shift from northeastern
Oklahoma Saturday to North Texas, southern Oklahoma, and into central
Arkansas on Sunday. There is a Marginal Risk of Excessive Rainfall for
this area on Sunday as totals over an inch, locally higher, may lead to an
isolated instance or two of flash flooding. Temperatures will be well
above average south of the front as forecast highs range from the 70s into
the low 80s.

Further north, a couple waves of wintry precipitation will overspread the
Upper Midwest Friday and Saturday as a couple upper-level disturbances
move by. Some freezing drizzle will be possible as well as snow showers,
though accumulations should remain on the light side, with 1-2 inches
possible. High temperatures will be near average for this time of year,
with 20s and 30s for the Upper Midwest and Northern Plains and 40s and 50s
from the Central Plains into the Ohio Valley and Lower Great Lakes. Highs
will be around or just below average for the East Coast as a ridge of high
pressure remains in place, with 30s and 40s in New England and the
Mid-Atlantic and 50s in the Carolinas. A front will approach the region
Sunday morning as the next upper-level disturbance moves eastward bringing
the chance for some light wintry precipitation early Sunday Morning from
the Northeast and into the Central Appalachians.

Putnam


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