Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
328 AM EST Wed Dec 21 2022

Valid 12Z Wed Dec 21 2022 - 12Z Fri Dec 23 2022

...Powerful winter storm to produce a multitude of weather hazards across
the central and eastern United States through the end of the week...

...Bitter cold and life-threatening wind chills over the northern Plains
to surge southward today and swing towards the East Coast on Friday...

...Significant freezing rain possible across parts of western Oregon and
Washington beginning Thursday night...

What better way to kick off the official start of astronomical winter than
with numerous winter weather hazards impacting a majority of the Nation.
At the forefront of the active weather pattern is a very strong arctic
cold front set to begin diving southward into the central Plains today and
the southern Plains by early Friday. This will not be your average cold
front as temperatures could drop 20 or more degrees within a few hours.
This alone could create flash freeze conditions on roadways where any
standing water doesn't dry quick enough. Meanwhile, a low pressure system
developing along this frontal boundary is forecast to rapidly strengthen
by Thursday night over eastern Michigan, which will aid in surging the
record-breaking frigid temperatures to the Gulf Coast and eastern U.S. by
Friday. This storm system is likely to produce widespread
light-to-moderate snowfall from the Midwest to the Great Lakes and
Interior Northeast, with a brief burst of snow also possible into the
Ohio/Tennessee Valleys and northern Mid-Atlantic immediately following the
cold frontal passage. The heaviest snowfall, with amounts potentially
exceeding a foot, is anticipated to occur over the Great Lakes between
tonight and Friday. Lake enhanced snowfall along with moisture wrapped
around the low will help aid in the locally heavy totals. Combined with
the snowfall, very strong winds will also accompany the system as a very
tight pressure gradient develops between the low over the Great Lakes and
the strong high pressure system over the northern Plains. Wind gusts over
50 mph and falling snow will result in blizzard conditions from the
northern/central Plains to the Great Lakes. Regardless of whether heavy
snow is falling or not, this combination will likely create extremely
dangerous travel conditions for both drivers and air travel. Scattered
tree damage and power outages are also possible, which could occur over a
large region from the Plains to the Northeast. In particular, damaging
winds are likely to develop over the Great Lakes on Friday and could
create a particularly dangerous situation combined with lake effect snow,
extreme cold, and possible power outages. Residents in these hardest hit
regions are advised make final preparations as soon as possible and check
on family and friends during the storm in case of an emergency. Strong
southerly winds ahead of the system will be the most impactful hazard for
the Northeast coastline and especially southern New England. Combined with
the new moon tide cycle, dangerous coastal flooding may stretch from
northern New Jersey to northeast Massachusetts. Heavy rain over a fresh
snowpack could also create scattered flooding concerns for parts of
Vermont and Maine on Friday as well, which has prompted a Slight Risk
(level 2/4) of Excessive Rainfall to be issued. Lastly, at the leading
edge of the northward surging moisture over the Mid-Atlantic during the
first half of the day on Thursday, light freezing rain and locally heavy
snowfall could impact parts of the central Appalachians. A lingering cold
air damming environment will likely keep this brief punch of wintry
weather confined to the higher terrain and near the Blue Ridge mountains,
but could still lead to snowfall totals up to six inches in spots.

The most widespread weather hazard over the next few days will be
associated with the extremely cold airmass set to spread across the
central and eastern two-thirds of the Nation. Wind Chill Warnings and Wind
Chill Watches currently stretch from the U.S.-Canadian border to the Texas
Gulf Coast, including portions of at least 26 states. These headlines have
been issued to highlight the dangerous and for some places record-breaking
cold temperatures. Wind chill values could drop as low as minus 70 degrees
throughout parts of the central High Plains. Widespread wind chills below
zero are forecast to extend as far south as Texas and parts of the Deep
South through the end of the week, as well as near the major cities across
the Northeast. Cold of this magnitude could lead to frostbite on exposed
skin within minutes, as well as hypothermia and death if exposure is
prolonged. Livestock interests will also be severely impacted and dangers
could be exacerbated if power outages occur.

The next storm system to impact the Pacific Northwest will spread
precipitation and gusty winds onshore by late Thursday ahead of an
approaching warm front. After initially starting out as snow, sleet and
freezing rain is likely to develop and could linger for an extended amount
of time over parts of western Washington and northwestern Oregon. This
changeover to freezing rain is due to a dense arctic airmass remaining in
place at the surface while warmer air surges over the region in the upper
levels. Localized ice accretion of a half inch could create the potential
for dangerous travel conditions and scattered power outages.


Snell

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