Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Tue Feb 21 2023

Valid 12Z Tue Feb 21 2023 - 12Z Thu Feb 23 2023

...A major winter storm will spread a large swath of heavy snow from the
West Coast to the Northeast through Thursday...

...Widespread very strong, gusty winds expected across the West and
adjacent High Plains...

...Heavy rain with the potential for scattered flash flooding and severe
weather for the Midwest and Plains Wednesday...

...Widespread record-breaking highs possible in the East and much below
average cold in the West beginning mid-week...

An energetic, amplifying upper-level pattern will bring numerous weather
hazards and significantly anomalous temperatures coast-to-coast this week
with almost all of the country experiencing some form of notable weather.
Snow will spread south and eastward across the West and the northern tier
of the country Tuesday into Wednesday as a trough deepens over the west
and embedded shortwave energy helps to push multiple frontal systems
across the region. Ample moisture will continue to stream in from the
Pacific and northward from the Gulf helping to fuel heavy snow rates. Snow
totals of 1-2 feet, locally higher, are expected for most of the mountain
ranges across the West. The heavy accumulating snow should be limited to
higher elevations in the mountains, with a lighter rain/snow mix for the
interior valleys. Moderate to locally heavy rain as well as some
thunderstorms are forecast for the lower elevation/coastal Pacific
Northwest Tuesday. Snow will begin to mix in with the rain as temperatures
cool Tuesday night into Wednesday, and there is even a chance to see some
light snow in the central California valleys. In addition to the snow, a
deepening low pressure system over the Great Basin and multiple fronts
pushing through the West will bring widespread very strong, gusty winds of
50-60 mph, locally as high as 80 mph in favorable terrain locations, to
most of the West and adjacent High Plains Tuesday-Wednesday. These winds
will lead to blizzard conditions for portions of the Northern/Central
Rockies and High Plains, areas of blowing dust, and an Elevated Risk of
Fire Weather Tuesday in the Southern High Plains as outlined by the Storm
Prediction Center.

An axis of heavy snow will also expand eastward across the Northern Plains
and into the Upper Midwest/Great Lakes and Interior Northeast/New England
Tuesday-Wednesday as a strong low pressure system organizes in the lee of
the Rockies and moves northeastward across the Plains/Midwest. Some
locations across the Upper Midwest/Great Lakes will have only a very brief
reprieve from a clipper system exiting the region before this next round
of heavy snow moves in. There is a high probability of snow totals over 8"
front South Dakota eastward through southern Minnesota, northern
Wisconsin, and the Upper Peninsula/northern Lower Peninsula of Michigan.
Locally higher totals of 1-2 feet are possible, particularly across
southern Minnesota. Heavy snow rates of 1-2" per hour and gusty winds
producing areas of blowing snow will lead to treacherous travel conditions
and potential power outages. Heavier snow totals of 8-12" are also likely
for higher elevations in the Interior Northeast including the Adirondacks,
Green, and White Mountains, with lighter accumulations of around 2-4
inches at lower elevations across Upstate New York and central New
England. A heavy wintry mix of snow, sleet, and freezing rain is expected
along the southern end of the snow axis across the Upper Mississippi
Valley and into the Lower Great Lakes. Ice accumulations of 0.1-0.25",
locally higher, are possible.

Widespread showers and thunderstorms are forecast to develop along along
the low pressure system's leading warm and cold fronts across the Midwest
and Plains Wednesday. Intense low-level and upper-level dynamics as well
as increased moisture spreading northward from the Gulf will lead to
locally heavier rain rates, with a Slight Risk of Excessive Rainfall
(level 2/4) from northeast Missouri into northern Illinois, northern
Indiana, and southern Michigan where there may be a few scattered
instances of flash flooding. It should be noted that uncertainty with the
location of the warm front could shift the location where the heavier,
convective rains transition to the heavy wintry mix expected just to the
north. Strong low-level and deep-layer shear and expected sufficient CAPE
values have also prompted a Slight Risk of severe weather (level 2/5) from
the Storm Prediction center from central Oklahoma northeastward through
central Missouri for the chance of some damaging winds.

Beyond the numerous weather hazards expected this week, another major
story will be the significantly anomalous warm temperatures for February
over the East and cold temperatures over the West. Highs on Wednesday will
be 20-30 degrees above average for many locations across the Southern
Plains, Midwest, and Southeast and 20-30 degrees below average over the
Northern/Central Plains and much of the West. Many record-tying/breaking
highs are possible particularly for the Ohio/Tennessee Valleys, where
temperatures will be into the 70s, and closer to the Gulf Coast/Florida,
where highs will be into the 80s. Many record-tying/breaking minimum high
temperatures will also be possible over the West, with highs in the 30s
and 40s for the Pacific Northwest and in the 50s for California. Bitterly
cold wind chills 20-30 degrees are expected for the Northern Plains. These
highly anomalous temperatures are forecast to continue later into the
week.

Putnam

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