Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
309 AM EST Tue Nov 23 2021

Valid 12Z Tue Nov 23 2021 - 12Z Thu Nov 25 2021

...Holiday travelers thankful as a relatively tranquil stretch of weather
persists in the final days leading up to Thanksgiving...

...Chilly temperatures in the East, warmer in the Heartland; Critical fire
weather areas in the central Great Plains...

...Unsettled weather in the Northwest, mountain snow in the Southern
Rockies; Swath of showers and thunderstorms from the mid-Mississippi
Valley to south Texas Wednesday night and Thanksgiving morning...

With Thanksgiving just a couple days away, Mother Nature is providing a
suitable weather pattern for travelers across the vast majority of the
U.S. mainland through Wednesday night. This is due to a dome of Canadian
high pressure in control of the weather pattern across much of the East.
This high pressure system has engulfed much of the eastern third of the
U.S. in an air-mass more akin to what is typically observed in the heart
of the holiday season. Freeze Watches and Warnings have been issued in
parts of the Southeast while Winter Weather Advisories remain in effect
downwind of Lakes Erie and Ontario early this morning. Daytime highs will
struggle to get out of the 40s in the Northeast today while much of the
Southeast sees high temperature departures ranging between 10 and 20
degrees below normal. Another chilly day is on tap up and down the East
Coast on Wednesday before warmer temperatures arrive on Thanksgiving.
Speaking of "warmer temperatures", an upper level ridge of high pressure
traversing the Nation's Heartland is responsible for a surge in abnormally
warm conditions from the Southwest to the Midwest today. The warmest
daytime high departures will be centered in the central Plains where highs
range anywhere from 15 to 30 degrees above normal. In addition, Critical
Risks for fire weather and Red Flag Warnings have been issued in parts of
the Great Plains due to favorable fire weather prospects today. This
dramatic warm-up will be short lived, however, as another intrusion of
cold Canadian high pressure plunges into the northern Rockies and Plains
on Wednesday, then sweeps across most of the Plains and Upper Mississippi
Valley by Thanksgiving. Most of the Intermountain West and West Coast will
also see temperatures plunge to below normal levels mid-week before
returning to more seasonally warm levels by Thanksgiving.

The main culprit for unsettled weather into the middle of the week is an
upper level disturbance tracking through the Northwest this morning. It is
ushering a stream of Pacific moisture into the Pacific Northwest that is
responsible for areas of coastal/valley rain and mountain snow today. Most
accumulations are forecast to be on the lighter side, although some of the
higher elevations (Cascades, Bitterroots, Lewis Range, Tetons) could pick
up as much as a foot of snow by the time the snow subsides Wednesday
evening. Farther south, a cold front crossing through the southern Rockies
may lead to spotty showers and accumulating mountain snow Tuesday night.
The aforementioned Pacific Northwest disturbance will head east and cause
an area of low pressure to form over the Great Lakes. As its trailing cold
front advances east through the nation's mid-section mid-week, this sets
the stage for scattered showers to breakout from the Lower Great Lakes to
the South Central U.S. Wednesday night. Some thunderstorms may also
develop in the southern Plains Wednesday night into early in the day on
Thanksgiving. Look for showers and thunderstorms to push into the Ohio and
Tennessee valleys later in the day on Thanksgiving with locally heavy
rainfall possible in southeast Texas. The regions most likely to stay dry
on Thanksgiving are the Southwest, Intermountain West, Midwest, and much
of the East Coast.

Mullinax

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