Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
449 AM EDT Tue Mar 22 2022

Valid 12Z Tue Mar 22 2022 - 12Z Fri Mar 25 2022

...Central and Northern Great Plains through Minnesota...
Days 1-2...

An occluded low pressure system drifts northeast from OK early
this morning, across MO through tonight, and to lower MI through
Wednesday night. Reinforcing waves/impulses will make the system
rather complex and sprawling. Exceptional moisture streaming ahead
of this system out the Gulf of Mexico and strong jet-level
diffluence makes for low-level frontal bands of snow to continue
to lift northeast up the Plains today, continuing over the
Arrowhead of MN into tonight. These dynamic bands will continue to
allow embedded snow to develop in the banding from west-central KS
into east-central Neb and slowly shift northeast across MN today.
Notable enhancement will come from the left exit region of the
southerly jet streak currently developing over eastern OK that
darts north through IA this morning and western WI this afternoon.
The 00Z HREF limits snowfall rates over 1"/hr to eastern Neb
through mid-morning, but  the persistence of the snow over MN
could also allow decent snowfall in that stripe. Day 1 snow
probabilities for over 2" are low to moderate in a stripe over
eastern Neb through southwestern MN (highest on Buffalo Ridge
where over 4" is most likely).

Areas farther north over northern MN will have lake enhancement as
well that the same left exit region upper level lift. There should
be several areas of far northeastern MN that have snow over 6"
including the North Shore escarpment.


...Great Lakes through the Northeast...
Days 1-3...

The sprawling low lifting northeast from eastern OK through MO
today will bring deep southerly flow and anomalously high moisture
northward across the Great Lakes today with the warm nose making
for mostly a rain/freezing rain decision today (left up to the sfc
temp). However, height falls from the approaching upper low will
allow snow to develop around the U.P. of MI tonight and continue
through Tuesday. Moderate Day 1.5 snow probabilities for over 4"
are over far northern WI and through the central/western U.P. of
MI. A wintry mix will persist in this time with quite the complex
mix of snow/sleet/freezing rain/rain across the northern Great
Lakes. As of now Days 1 and 1.5 ice probabilities are moderate for
0.1" ice from the North Shore of Lake Superior across northern MI
with probabilities for over 0.25" generally limited to 30% for the
Keweenaw Peninsula and the Huron Mtns.

The sprawling low expands into the Northeast Wednesday, continuing
through Thursday night. Warm air advection on this side of the
system does allow some freezing rain to occur mainly in elevation
across the Northeast. Days 2 WPC ice probabilities for over 0.1"
are moderate Adirondacks, Catskills, Berkshires, and Green
Mountains, expanding to include the White Mtns of NH/Maine for Day
3.


Jackson