Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EST Tue Dec 20 2022

Valid 12Z Tue Dec 20 2022 - 12Z Thu Dec 22 2022

...Heavy snow likely across parts of the Pacific Northwest and northern
Rockies through midweek...

...Bitter cold and dangerous wind chills over the northern Plains to surge
southward into the central U.S. by Thursday...

...Light to moderate snow combined with gusty winds to overspread much of
the central Plains and Upper Midwest beginning on Wednesday...

Plenty of winter weather to go around throughout the Nation during the
week of the winter solstice, with potentially hazardous weather conditions
spanning from the Northwest and Great Plains to the central/southern
Appalachians through midweek. A strong arctic high pressure system
extending from western Canada to the northern Plains will continue to lead
to very cold air over the region while extending into much of the Pacific
Northwest. As this cold airmass gradually sinks into more of Washington
State, an approaching storm system and surge of moisture will lead to
widespread snow to impact northern and western portions of The Evergreen
State. Snow is likely to fall across the lowlands as well and could be
heavy at times, leading to dangerous travel conditions. The heaviest
snowfall amounts are expected in the higher terrain of the Cascades and
into northern Idaho, northwest Montana, and western Wyoming. These regions
will have the best chances for over a foot of snow. Winter Storm Warnings
and Winter Weather Advisories are in effect. The next wave of potential
winter weather is forecast to enter the Pacific Northwest on Thursday,
with additional lowland snow and/or ice possible.

The aforementioned repository of dangerous arctic air over the northern
Plains and western Canada is expected to dump southward following behind
the system crossing the Pacific Northwest today. Subzero readings with
minimum values nearing minus 20 and minus 30 degrees over the northern
tier will enter into the northern Great Basin, northern Rockies, and much
of the Great Plains by Thursday. Combined with wind gusts up to 60 mph,
widespread wind chill values could drop to around minus 40 degrees
throughout the central and north-central United States. This level of cold
can be life threatening and lead to frostbite on exposed sin in as little
as 10 minutes. Wind Chill Warnings and Watches currently span across 17
states from Washington to Texas.

Along with the bitter cold air, snow is likely to add to the pre-holiday
travel headaches from the central Plains to the Upper Midwest. Areas of
light to moderate snow are likely along and behind the cold front as it
impacts the region on Wednesday and Thursday. Snowfall amounts for this
time period are not expected to be that impressive until a rapidly
strengthening low pressure system forms along the front and races towards
the Great Lakes. Greatest chances for over 8 inches of snow is found
across states that surround Lake Michigan. It is this area that is
expected to receive the longest duration of snowfall and within a very
cold airmass. Along with the snowfall, very strong winds are expected to
impact nearly the entire easter half of the U.S. as this large system
becomes fully mature by Thursday night. Winds will create blowing and
drifting snow over locations with fresh snow cover, which can exacerbate
hazardous travel. Additionally, the strong winds will lead to potential
power outages from the Midwest to the Northeast. With such a large and
powerful storm system impacting a majority of the Nation during one of the
biggest travel weeks of the year, it is imperative that travelers check
the latest forecast before venturing out.

Elsewhere, unsettled weather with moderate to locally heavy rain is
possible across the Southeast today as a low pressure system slides
eastward along a frontal boundary. Moisture is then expected to lift
northward into the Mid-Atlantic and Appalachians on Thursday as the
deepening system organizes to the west. Cold air damming in place could
allow for a period of snow, sleet, and/or freezing rain across parts of
the central Appalachians. Otherwise, moderate rainfall and strong
southerly winds are anticipated to spread up the East coast into the
overnight hours on Thursday.


Snell

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