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

Valid 12Z Thu Dec 09 2021 - 12Z Sat Dec 11 2021

...Winter storm to produce the first widespread and significant snow of
the season throughout the Intermountain West and Central Rockies today
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 the beginning of this weekend...

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 breakout over the Sierra Nevada and Intermountain West this
morning and last into the evening hours. Additionally, cold air filtering
from the north will allow for snowflakes to fall into the lower elevations
of central Nevada and Utah, which could possibly lead to dicey travel
conditions. Snow is also forecast to spread into the Central Rockies and
parts of the central High Plains by 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 found along
and ahead of a strong cold front forecast to reach the Middle/Lower
Mississippi Valley by Friday evening. It appears probable 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. Heavy rain and
isolated flooding concerns may also accompany the region.

Other areas of notable precipitation will be found across the Upper
Midwest/Great Lakes today and Pacific Northwest by Friday night. Light
snow and a wintry mix is likely to swing through parts of Wisconsin and
northern Michigan as a warm front nears the region. A few inches of snow
may accumulate and set the mood for the approaching and 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 over 2 feet are possible in the
Cascade and Olympic Mountains.

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 day. 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 quickly build into the eastern U.S. by Saturday,
where highs into the 70s are possible as far north as southern New Jersey.
Numerous daily high temperature records are likely to break over the next
three days.


Snell

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