Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
305 AM EST Tue Dec 28 2021

Valid 12Z Tue Dec 28 2021 - 12Z Thu Dec 30 2021

...Spring like temperatures persist in the South and East; elevated fire
weather risk for parts of the Southern Plains; bitterly cold wind chills
in the northern Rocking and High Plains today...

...Wintry weather to cause treacherous travel conditions from the Midwest
to the interior Northeast today; Slight Risks for severe storms and
Excessive Rainfall posted in parts of the Deep South Wednesday...

...Heavy snow for parts of the Sierra Nevada and Central/Southern
Rockies...

The jet stream pattern heading into the middle of the week continues to
indicate troughing in the west and ridging in the Southeast. The result is
a distinct separation of air-masses; winter is in full control in the West
while spring-like temperatures are firmly entrenched in the South and East
Central U.S.. Numerous record high temps and warm daily lows are expected
throughout much of the South with daily temperature departures ranging
between 25 to 35 degrees above normal. The mixture of anomalous heat, very
dry conditions, and gusty winds keeps an Elevated Risk area for fire
weather conditions in place atop the southern High Plains. The anomalous
warmth backs off slightly in the South by Thursday, but lows that are
warmer than the normal highs for late December will be common up and down
the East Coast Thursday morning. In the West, much colder temperatures are
expected with the coldest temperatures in the Northwest, northern Rockies,
and northern High Plains. Daily low temperatures will fall below -20
degrees in parts of Montana and North Dakota, which combined with gusty
winds cause wind chills to plummet as low as 50 degrees below zero through
Tuesday morning. Even daytime highs will struggle to get above zero in
these regions. The West Coast has the best chance to witness record cold
max temperatures through Wednesday.

As upper level disturbances track through the Intermountain West and head
east into the Plains, unsettled weather will become increasingly more
common in parts of the South and East. The first storm system is beginning
to unfold this morning in the central Plains with precipitation blossoming
from the Texas Panhandles to the Midwest. Light but still potentially
hazardous wintry weather is on tap from the Midwest and Great Lakes to the
northern Mid-Atlantic. Winter Weather Advisories have been posted not just
for up to a few inches of snow, but also an icy wintry mix of snow, sleet,
and freezing rain that could result in up to a tenth of an inch of ice
accumulation in some of these regions. Within the storm's warm sector,
periods of rain are expected from the Middle Mississippi Valley to the
Ohio Valley. Rain may fall heavily at times and could lead to localized
flash flooding, thus prompting the issuance of a Marginal Risk for
Excessive Rainfall. Farther south, thunderstorms are in the forecast for
the Lower Mississippi and Tennessee Valleys with a Marginal Risk for
severe storms in southeast Louisiana. As a new upper level disturbance
ejects out of New Mexico on Wednesday morning, it will support and even
more favorable environment for severe weather and excessive rainfall later
in the day on Wednesday. This has prompted the issuance of Slight Risks
for both potential hazards in the Tennessee Valley and Deep South.
Meanwhile, the threat for Excessive Rainfall will remain problematic in
parts of Southern California where a Slight Risk was also issued for
Wednesday

The ongoing troughing pattern out West will keep generating wintry weather
from the Sierra Nevada to the southern and central Rockies. The heaviest
snowfall accumulations will be confined to the Mogollon Rim of Arizona and
the Rockies of Colorado and northern New Mexico. Snowfall totals in the
highest peaks will generally average 1 to 2 feet today with locally higher
amounts possible. Lighter accumulations compared to recent days are
anticipated today along the West Coast, but the next upper level feature
diving through the West Coast will usher in yet another round of heavy
snow to the Sierra Nevada late Tuesday into Wednesday. By early Thursday
morning, another 1 to 2 feet of snow will have fallen in throughout much
of the Sierra Nevada with locally higher totals in the tallest peaks.
Expect more hazards travel conditions in these mountain ranges through the
middle of the week.

Mullinax


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