Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
251 PM EST Thu Dec 09 2021

Valid 00Z Fri Dec 10 2021 - 00Z Sun Dec 12 2021

...Winter storm to produce the first widespread and significant snow of
the season throughout the Intermountain West and Central Rockies tonight
before spreading into the Great Plains and Upper Midwest on Friday...

...Severe thunderstorms possible for parts of the Lower Mississippi,
Tennessee, and Ohio valleys on Friday night...

...Strong storm system to enter the Pacific Northwest on Friday night...

...Record-breaking warmth to build across the south-central and eastern
United States through Saturday...

Much of the active and potentially hazardous weather over the Lower 48
during the short term will be associated with a developing winter storm
that is poised to produce a long stretching swath of heavy snow from the
Intermountain West to the Upper Great Lakes. Light-to-moderate snow is
expected to continue across the Intermountain West this evening.
Additionally, cold air filtering from the north will allow for snowflakes
to fall into the lower elevations of central Nevada and Utah, which could
lead to dicey travel conditions. Snow is also forecast to spread into the
Central Rockies and parts of the central High Plains tonight as an
upper-level trough swings eastward. Snowfall amounts of 1-2 feet are
forecast across the Rockies of western Colorado and Utah, with widespread
accumulations of 6-8 inches likely into the Wyoming Front Range. As the
system continues to progress eastward on Friday, an area of low pressure
is forecast to develop over the Colorado Front Range and race northeast
into the Midwest by Friday night. As a result, a stripe of heavy snow is
expected to the north of the low and across parts of the Central/Northern
Plains and Upper Midwest. Specifically, snowfall amounts greater than 6
inches are likely to have fallen by Saturday morning along the
Nebraska-South Dakota border, northwest Iowa, southern Minnesota,
northern/central Wisconsin, and the U.P. of Michigan. The combination of
heavy snow and gusty winds will lead to hazardous driving conditions
throughout these regions. Given this is the first widespread and
significant snowfall of the season, residents in these areas are urged to
plan ahead and take proper precautions if venturing out into the storm.
Winter Storm Warnings/Watches and Winter Weather Advisories have been
issued.

The other aspect of this early-December winter storm will be thunderstorm
activity along and ahead of a strong cold front forecast to reach the
Middle/Lower Mississippi Valley by Friday evening. It appears likely that
thunderstorms will turn severe from the Lower Mississippi Valley to the
Lower Ohio Valley into Friday night. Damaging wind gusts and tornadoes are
the main concern, with large hail possible as well. Most of these
thunderstorms are expected to occur overnight, which can be particularly
dangerous when tornadoes are a possibility. The Storm Prediction Center
has issued an Enhanced Risk (level 3/5) of Severe Weather from eastern
Arkansas and northwest Mississippi to far southern Indiana. Some severe
cells may produce isolated occurrences of heavy rain and flash flooding.

Light snow and a wintry mix is likely to swing through parts of Wisconsin,
northern Michigan and the interior Northeast as a warm front glances
across the region tonight through Friday morning. A few inches of snow may
accumulate before the arrival of the aforementioned winter storm.
Otherwise, after a few scattered mountain snow showers and coastal rain
showers today, a strong cold front is forecast to reach western Washington
by Friday night. Gusty winds and heavy precipitation will be the main
impacts. Snowfall amounts of 2-3 feet are possible in the Cascade and
Olympic Mountains with the highest peaks possibly reaching 4 feet by
Saturday night. Heavy snow will also spread into the Northern Rockies on
Saturday as the cold front pushes through the region. This same cold front
will produce much needed rain and snow for California, where much of the
state is under 'extreme' or 'exceptional drought.' This may lead to flash
flooding or landslides over sensitive surfaces.

Meanwhile, winter is nowhere to be found throughout the south-central U.S.
with well above average temperatures set to expand eastward over the next
few days. Highs into the 70s and 80s are expected in the Southern Plains
today and Mid-South by Friday ahead of the advancing cold front. These
warm temperatures will move into the eastern U.S. by Saturday, where highs
in the 70s are possible as far north as southern New Jersey. Numerous
daily high and low temperature records are likely to break over the next
three days. Critical fire weather risk is in effect on Friday for parts of
northeastern New Mexico and the Texas panhandle due to strengthening winds
and dry conditions brought on by the deepening winter storm to the north.


Kebede/Snell

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