Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
354 AM EST Mon Jan 22 2024

Valid 12Z Mon Jan 22 2024 - 12Z Thu Jan 25 2024

...Southern Plains to the Great Lakes...
Days 1-2...
A mid-to-upper level trough centered over the Southwest will
continue to move east, assuming a negative-tilt as it pivots east
of the Rockies and into the High Plains later this morning.  This
morning's radar shows precipitation spreading northeast from the
southern Plains through the mid Mississippi Valley.  As the cold
air aloft retreats in the face of strong southwesterly flow,
lingering cold air at the surface is supporting mixed
precipitation, including areas of freezing rain from the Red River
Valley northeastward.  Periods of freezing rain are expected to
continue during the morning from the Red River north and east
across western to central Arkansas and southern Missouri before
changing over to rain as the warm air wins out ahead of the
approaching shortwave.  Ice accumulations of 0.10 inch or more are
likely across portions of central Arkansas and southern Missouri,
with the WPC PWPF showing probabilities over 50 percent for
accumulations of 0.25 inch or more centered over south-central
Missouri.

Father to the north, the light precipitation including snow and
freezing rain will spread as far north as Lower Michigan beginning
later this morning.  This will be followed by a break before
precipitation begins to spread northeastward from the mid
Mississippi Valley into the Great Lakes ahead of the shortwave
lifting out of the southern Plains.  Precipitation is expected to
begin as freezing rain during the evening and overnight hours from
central Illinois northeastward into southern Wisconsin and
Michigan.  Overnight models have trended colder, presenting a
strong signal for significant ice accumulations across the region.
 The latest PWPF indicates that ice accumulations exceeding 0.10
inch are likely from central Illinois to northern Indiana and
northwestern Ohio.  Along this axis, the PWPF also shows localized
probabilities above 40 percent for ice accumulations of 0.25 inch
or more by early Tuesday.  Meanwhile to west along the wave's
associated deformation band, a wintry mix is expected as well,
with freezing rain along the northern edge changing over to snow
as the column cools.  Confidence in the details is limited,
however at least minor ice and/or snow accumulations appear likely
from eastern Nebraska through northern Missouri into Iowa.

As the wave continues to lift northeast into the Great Lakes,
before being sheared by confluent flow over the Great Lakes into
the Northeast, light snow will lift north and spread east across
the Great Lakes into the Northeast, with freezing rain to the
south.  Probabilities for snow accumulations of 4 inches or more
during the Day 2 period are less than 5 percent for most areas,
with the exception of the Adirondacks, the Green and White
mountains.  Probabilities for ice accumulations exceeding 0.10
inch are highest from north-central Pennsylvania into the
Catskills.

...California to the Southwest...
Days 1-2...
A series of shortwaves impacting the West continues this morning,
with another amplifying wave moving across California later today.
 This will bring another round of heavy snow to portions of the
Sierra Nevada.  WPC PWPF shows high probabilities for
accumulations of 6 inches or more, mostly for areas above 7000 ft.
 As the upper trough moves east, snow will spread into the Great
Basin, with locally heavy amounts possible in the Nevada mountains
beginning later today, mainly above 7000 ft.  Snow will also
develop along the Mogollon Rim southeastward into the east-central
and southeastern Arizona mountains, where the PWPF shows some
locally high probabilities for accumulations of 4 inches or more.

Pereira