Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
324 AM EST Fri Mar 04 2022

Valid 12Z Fri Mar 04 2022 - 12Z Mon Mar 07 2022

...West...
Days 1-3...

A pair of upper level lows are expected to impact the western U.S.
today.  Across the southwestern U.S., an upper low centered along
the coast of Southern California is forecast to move inland later
this morning.  This system is forecast to transition to an open
wave as it moves across the Southwest during the day, before
lifting northeast across the southern Rockies tonight and into the
central High Plains Saturday morning.  This is expected to bring
high elevation snow, with locally heavy amounts possible, from the
Southern California mountains, across the mountains and Mogollon
Rim of northern and central Arizona, into the central Rockies. 
WPC probabilities show the greatest threat for snow accumulations
of 8 inches or more across the San Juan Mountains in southwestern
Colorado, where southwesterly flow ahead of the approaching
shortwave, along with left-exit region upper jet forcing, is
expected to help bolster totals on Friday.

Meanwhile, a second upper low is forecast to develop and drop
southeast along the Pacific Northwest coast later today.  This
will bring the increasing potential for heavy snow as it moves
into interior Northern California tonight.  WPC probabilities
indicate that accumulations of 4-8 inches are likely, with locally
heavier amounts possible, across the northeastern corner of
California.  This includes across the Modoc Plateau into the
Warner Mountains and the northern Sierra.

This low is forecast to slide southeast into southern Nevada and
Utah Saturday night and Sunday morning.  WPC probabilities, show
accumulations of 4-8 inches are likely, with locally heavier
amounts possible by early Sunday across the central to eastern
Nevada and Utah mountains.

Models show this system transitioning to an open wave as it moves
from the Four Corners region into the central and southern Rockies
during the day on Sunday.  This will bring some additional, mainly
light accumulations across the central Rockies into the High
Plains.

...Central High Plains through the Great Lakes...
Days 1-3...

Light to moderate precipitation falling in the form of a wintry
mix is expected to develop across portions of the Upper Midwest
overnight into Saturday.  Models show a weak shortwave emanating
from the base of the upper trough over the Southwest lifting
quickly to the northeast -- supporting light precipitation as it
moves into the Upper Midwest overnight.  A mixture of snow, sleet,
and freezing rain is expected from southern Minnesota to Upper
Michigan Friday night into Saturday, with WPC probabilities
indicating the greatest potential for ice accumulations of 0.10
inch or more centered across northeastern Wisconsin.

Meanwhile, the more amplified shortwave crossing the Southwest on
Friday is expected to lift northeast into the central High Plains.
 By Saturday morning the potential for heavy snow is expected to
increase across the southeastern Wyoming mountains and the
Colorado Front Range before shifting northeast into the Nebraska
Panhandle and southwestern South Dakota later in the day. 
Northeasterly flow on the backside of a 700mb low, along with
favorable upper forcing will support the potential for heavy rates
on Saturday.

Models show the system amplifying as it lifts from the central
Plains into the Upper Midwest Saturday evening.  Models continue
to show much of the heavier precipitation in the associated
commahead falling as a wintry mix changing to snow across the
Upper Midwest.  Ice accumulations of 0.10 inch or more are likely
across portions of northern Wisconsin into Upper Michigan.

Pereira