Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
1213 AM EST Fri Dec 31 2021

Valid 12Z Fri Dec 31 2021 - 12Z Sun Jan 02 2022

...Record breaking Spring-like temperatures in the South to reach the
portions of the East Coast...

...Winter weather, flash flooding, and severe weather to usher in 2022...

The continental U.S. remains under the influence of prolonged troughing in
the Intermountain West and ridging in the Southeast. The combination of
cold air aloft and Pacific moisture will focus another moderate-to-heavy
snow chances throughout much of the Intermountain West as the system dives
toward the Great Basin. Further south, a developing storm system off the
California coast will continue to usher Pacific moisture into Southern
California and the Southwest Friday.  By Saturday morning, mountain ranges
such as the Cascades, Sawtooth, Wasatch, and both the central and southern
Rockies can expect 1 to 2 feet of snow with totals exceeding 3 feet in the
highest elevations of Utah and Colorado. Another injection of frigid
Arctic air causes temperatures to plummet throughout the Plains on Friday
and into Saturday morning, with sub-zero temperatures expected from the
Upper Mississippi Valley to the Northern Rockies. Wind Chill Warnings and
Advisories remain in effect for the far North Central U.S. through
Saturday.

Farther south and east on the warm side of the front, abnormally warm and
humid conditions will stick around in the Southeast with considerably
milder conditions spreading as far north as the Northeast by New Year's
Day. Numerous record highs are expected from the Gulf Coast to the
northern Mid-Atlantic through Saturday morning, with some record warm low
temperatures most likely in the Southeast.  The troughing in the West and
the strong ridge of high pressure over the Southeast will funnel moisture
into the Mid-South late Friday.  The developing storm system in the Plains
will set the stage for another active day of severe weather from North
Texas to the southern Appalachians on Friday.  Ample moisture and
instability is also present to support high rainfall rates, making flash
flooding a concern in the Middle Mississippi and Ohio/Tennessee River
Valleys.  As a result, Slight Risks have been issued for both severe
storms and flash flooding in these regions on Friday, with concerns for
nocturnal severe weather and localized flooding.

As the storm system responsible for Friday's potential severe weather and
flash flooding event emerges into the South Central U.S. Saturday morning,
the New Year is forecast to start off wintry as measurable snowfall and an
icy wintry mix are expected to cause widespread hazardous travel
conditions New Year's Day from the Central Plains to the Great Lakes.
Several inches of snowfall are likely with this impending storm, with 6-8+
inches of snowfall possible within heavier snowfall bands.  Significant
mixed precipitation is possible south of the heavy snow activity, leading
to widespread moderate potential winter storm impacts over the Central
Plains and Midwest per the WPC Winter Storm Severity Index.  Within the
storm's warm sector, another busy day of severe weather and Excessive
Rainfall is likely in the Mid-South, with another round of severe weather
and a moderate risk of Excessive Rainfall from the Ohio/Tennessee River
Valleys southwestward toward ArkLaTex.  By Sunday, the progressive system
shifts the heavy rain and severe weather threat into the Southeast and
southern Appalachians.

Roth


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