Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
336 AM EDT Sun Apr 03 2022

Valid 12Z Sun Apr 03 2022 - 12Z Wed Apr 06 2022

...Northeast...
Day 1...

Amplified shortwave will move through the region today in tandem
with a lead area of low pressure along the NY/PA border. Snow in
the morning will change to a rain/snow mix over many areas during
the afternoon as a secondary area of low pressure develops off the
NJ coast by the afternoon. Generally light amounts are expected,
though some higher totals around 4 inches are possible in the
higher elevations of the Catskills. 

...Upper Midwest/Great Lakes...
Days 1-3...

A shortwave and organizing surface low over North Dakota this
morning will quickly move into the Upper Midwest/Corn Belt this
afternoon/evening. A disjointed stripe of an inch or two of snow
is possible over portions of central southern North Dakota
east-southeastward into Wisconsin and Lower Michigan tonight into
Monday. Thermal profiles will be marginal over southern Wisconsin
where potential exists for several inches of snow as an area of
FGEN moves across the area, promoting lift into the DGZ for a
brief window Monday morning. WPC snowband tool does show a few
members with 1"/hr rates for a time. Otherwise, WPC probabilities
for at least 4 inches of snow are low but focused over
southern/southeastern Wisconsin.

On Day 3, front associated with the Pac NW event (section below)
will move into the northern Plains. Mid-level shortwave will dig
and close off over the Dakotas into Minnesota late Tuesday into
Wednesday. Stacked system will occlude and wrap up with a surge in
moisture from the south (not quite the Gulf) on the warm conveyor
belt into the colder air mostly near the Canadian border. A few
inches of snow are likely for at least the Arrowhead of Minnesota
where temperatures should be cold enough for snow. WPC
probabilities for at least 4 inches of snow are low at this time.


...Northwest to the northern Rockies...
Days 1-3...

Lead/weak system will push into western Washington this morning,
but by tonight, the strong/extended jet (~170 kts) across most of
the Pacific will aim into the Northwest coast with a significant
moisture flux reaching into western Washington/Oregon.
Precipitable water values will reach +1 to +2 sigma Monday ahead
of a cold front that will move through the region as a west-east
stretched vort max streams eastward.  West-southwest flow will
capitalize on upslope into the Olympics and Washington Cascades
where widespread accumulations of 1-2+ ft are likely and multiple
feet are possible across the higher peaks. Significant
accumulations are possible at some passes as well. Along the
Oregon Cascades, lesser amounts are expected into early Monday
when snow levels will be higher. By early Tuesday, snow levels
will drop to around 2000ft across WA as the precipitation only
starts to wind down. Accumulations over the Oregon Cascades will
increase markedly on Monday. High pressure will move in late
Tuesday, helping to push the precipitation eastward. Snow will
spread across Idaho/western Montana Monday and into Wyoming
Tuesday with several inches likely above 6000ft. Snow levels will
lower quickly Tuesday morning to most valley floor locations but
with little accumulation. Snow will ease and wind down on Day 3 as
the front sinks southward and eastward.


...Colorado/New Mexico Rockies...
Day 1...

Weak upper trough and surface cold front will lead to an increase
in snow over higher elevations of Colorado today, aided by upslope
flow as a small area of high pressure sinks southeastward over the
Plains. At least a few inches of snow can be expected across the
higher elevations of the central Colorado and far northern New
Mexico ranges.


For Days 1-3, the probability of significant icing of at least
0.25" is less than 10 percent.


Fracasso