Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
306 PM EST Mon Dec 27 2021

Valid 00Z Tue Dec 28 2021 - 00Z Thu Dec 30 2021

...A pair of dynamic low pressure systems will bring snow to the Upper
Midwest/Great Lakes and showers and thunderstorms to much of the Midwest
and Southeast beginning Tuesday...

...Warm air expands into Northeast, while cold spreads into Upper Midwest;
elevated fire weather risk for parts of the Central/Southern Plains...

...Heavy snow for parts of the Central/Southern Rockies...

A seemingly anchored upper level pattern, with persistent troughing in the
west and ridging in the Southeast will lead to more predictable weather
across the CONUS over the next few days. In the west, a low pressure
system will bring snow to portions of the Intermountain West and
Southern/Central Rockies beginning tonight. Generally 12-18 inches are
expected, while the highest peaks may accumulate over 2 feet of snow by
Wednesday evening. The Sierra will receive some snow while the rest of the
state contends with light to moderate rainfall. The heaviest rain will
fall over southern California tonight through Wednesday. To the north of
the precip, a cold airmass which has situated itself over the Northern
Plains/Rockies and Intermountain West will gradually retract and expand
across the Northwest. High temperatures over parts of eastern Montana and
northwestern North Dakota are forecast to peak around 10-15 degrees below
zero on Tuesday and Wednesday, while lows will be in the -20s both nights.

As warm air spreads from the Southern Plains into the Mid-Atlantic and
Northeast over the next few days, so will the chance for unsettled
weather. Surface low pressure systems will ride along a pair of shortwaves
ejecting from the Rockies and go on to produce light to moderate snowfall
for parts of the Upper Midwest/Great Lakes as well as rain showers and
thunderstorms for much of the Midwest, Mid-Atlantic and Southeast starting
tomorrow. Upper Midwest snowfall may accumulate between 4-6 inches with
locally higher amounts. Intense thunderstorms and a quasi-stationary front
may lead to flash flooding threats, particularly over areas that receive
the most influx of moisture from the Gulf of Mexico, i.e. parts of the
Midwest, Middle Mississippi Valley and Southern Appalachians. The
anomalously warm air mass generated by an upper-ridge over the Southeast
will lead to the potential for widespread high temperature records being
broken across the Southern Plains, Lower Mississippi Valley and eventually
Tennessee Valley over the next couple of days. Warm and dry conditions
beneath a strengthening low pressure system that will enhance winds may
lead to the threat of fire weather across portions of the Southern/Central
Plains through Wednesday.

Kebede


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