Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
258 PM EST Thu Dec 17 2020

Valid 00Z Fri Dec 18 2020 - 00Z Sun Dec 20 2020

...Record breaking December winter storm heads out to sea this evening,
cold and dry conditions to linger over the Northeast to end the week...

...Light snow expected across the northern and central Rockies, showers
and thunderstorms possible in the South Central U.S. on Saturday...

...Coastal/valley rain and mountain snow continues across the Pacific
Northwest...

Snow falling along the New England coast this afternoon will come to an
end later tonight as last night's Nor'easter heads out to sea. Astonishing
snow totals were observed across the interior Northeast with some
locations seeing more than 40 inches of snow. As the storm exits east a
dome of Canadian high pressure builds in, leading to a dry and cold
stretch of weather this evening and through Friday. Lows will range from
the 10s to 20s from the Northeast on south into the northern Mid-Atlantic.
This will lead to re-freezes and patchy areas of black ice on untreated
roads. High temps may struggle to get above freezing on Friday and
Saturday in locations with deep snow pack.

As the weather quiets down up and down the East Coast, the more active
weather pattern sets up across the western half of the country. An upper
level trough swinging through the Great Basin is responsible for snow
falling across the northern and central Rockies this evening. Over 6
inches of snow is likely in the higher elevation regions of the
Intermountain West. Isolated travel disruptions can be expected in the
typical slick spots, but overall nothing too uncommon for the region. By
Friday morning, the storm system heads into the Plains with light snow
expected in the central High Plains. The aforementioned upper trough
reaches the Southern Plains on Saturday and is expected to develop a new
wave of low pressure in the western Gulf of Mexico. Scattered showers and
thunderstorms are likely to track through the South-Central region and
into the Lower MS Valley Saturday afternoon. Meanwhile to the north, a
cold front racing across the Upper Midwest looks to trigger snow showers
across northern Minnesota, northern Wisconsin, and the upper peninsula of
Michigan.

The Pacific Northwest has experienced several rounds of precipitation over
the last week and this pattern should continue over the next couple of
days. Precipitation across the region will back down to a degree
overnight, but a new Pacific storm system arrives on Friday with
coastal/lower elevation rain and heavy snow in the Cascades and Olympics.
Another break in the action arrives on Saturday, but yet another storm
system looks to slam into western Washington Saturday night. In total over
the next couple days, anywhere from 1 to 2 inches of rainfall is possible
in parts of western Washington and Oregon. The northern Cascades could
accumulate up to 2 feet of snow through Saturday evening.

Mullinax


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