Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
351 AM EST Wed Mar 09 2022

Valid 12Z Wed Mar 09 2022 - 12Z Sat Mar 12 2022

...Northern Mid Atlantic and Northeast...
Day 1...
Precipitation associated with a fast-moving mid level shortwave
will continue to spread north through the Mid Atlantic this
morning and into the Northeast by early afternoon.  Reflecting the
warm current temperatures, guidance has been shifting the southern
edge of accumulating snows farther to the north.  However there is
still significant potential for at least a couple of inches of
snow, especially on grassy surfaces, across portions of the
interior northern Mid Atlantic and the Northeast.  WPC
probabilities have decreased some, but still remain high for
accumulations of 2 inches or more across portions of the Northern
Tier of Pennsylvania and Southern Tier of New York into the
Poconos, Catskills, and Berkshires, with a slight chance (10-30
percent) for amounts of 4 inches or more across those areas.  

...Western U.S., including the central and southern Rockies...
Days 1-3...
A shortwave dropping south into the Pacific Northwest this morning
will continue to amplify and dig south across the region, driving
a strong baroclinic zone farther south across the Great Basin and
central Rockies today into early tomorrow.  Overall, expecting
mostly light accumulations over the next 24 hours across the
higher elevations of the Great Basin into the central Rockies. 
However, locally heavy accumulations of 8 inches or more are
possible, especially along the southern Wasatch and the western
Colorado ranges.  East of the Divide, upslope flow on the backside
of a low level wave dropping south across eastern Colorado will
support snow spreading south along the Front Range and adjacent
High Plains.  WPC probabilities show accumulations of 4-8 inches
likely, with locally heavier amounts possible along the Front
Range and southern Medicine Bow Mountains today.

On Thursday, the low in the High Plains is forecast to drop
southeast across the Texas Panhandle into western Oklahoma, with
the trailing boundary pushing south through eastern New Mexico. 
Upslope flow/low level convergence, coupled with favorable upper
jet forcing, is expected to support the potential for heavy snow
along the Sangre de Cristo and San Juan mountains.  WPC
probabilities indicate that accumulations of 4-8 inches are
likely, with significant potential for locally heavier amounts,
especially along the Sangre de Cristo Mountains.  Meanwhile
farther to the west, the previously noted upper shortwave digging
through the western U.S. is forecast to drop into the Southwest,
bringing at least light snows into the higher elevations of
northern and central Arizona on Thursday.

As the upper trough pivots east, some generally light snows are
expected to spread south into southern New Mexico and far western
Texas before the trough moves east of the region and surface high
pressure settles in late Friday.

...Central Plains to the Mid Mississippi Valley...
Days 1-2...
There remains a good signal for at least light to moderate and
potentially heavy snows developing over far northeastern Colorado
and spreading east across southwestern Nebraska and northwestern
Kansas beginning later today and continuing through the overnight.
 Deepening moisture along a low-to-mid level front, along with
favorable upper jet forcing, is expected to support the
development of snow across this region.  Probabilities have
shifted slightly south from the daytime run, but still indicate
that by early Thursday accumulations of 4-8 inches are likely
along an west-east axis extending from northeastern Colorado along
the western Nebraska and Kansas border.  WPC probabilities still
show a slight chance (10-30 percent) for accumulations of 8 inches
or more across a small portion of southwestern Nebraska and
northwestern Kansas. 

This initial band is forecast to shift east across eastern Kansas
into northern Missouri and southern Iowa Thursday morning into the
afternoon before weakening, with generally light snow spreading
northeast into the western Great Lakes during the evening and
overnight.  However, southerly flow into a lingering low level
boundary is expected to support redeveloping snows over Kansas,
then shifting south along the with the boundary into northern
Oklahoma and the Texas Panhandle Thursday night and Friday morning.

...Southern Plains to the Northeast...
Day 3...
On Friday, the southern stream shortwave moving out the southern
Rockies will begin to phase with a northern stream trough
amplifying over the Midwest.  Ahead of of the southern stream
wave, generally light to moderate snow is expected to spread east
from Oklahoma and northern Texas through southern Missouri and
northern Arkansas, into the Mid South and lower Ohio Valley along
a low-to-mid level frontal band.  By Friday evening, surface low
pressure is forecast to quickly develop and track northeast from
the central Gulf Coast region into the Carolinas by Saturday
morning.  Snow is expected to develop west of the low and along a
strong low-to-mid level front pushing east across the Ohio Valley
and eastern Great Lakes Friday night and Saturday morning.  For
the 24 hour period ending Saturday morning, WPC probabilities
indicate a moderate chance (40 percent) chance for snow
accumulations of 4 inches extending from portions of eastern
Tennessee and Kentucky to the Lower Great Lakes region.

Pereira