Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
446 PM EDT Sun Apr 10 2022

Valid 00Z Mon Apr 11 2022 - 00Z Thu Apr 14 2022

A long duration winter storm and blizzard, producing significant
snow and strong winds will impact portions of the northwestern to
the north-central U.S. through midweek.

...Pacific Northwest...
Days 1-3...
An active weather pattern continues for northern CA through WA
through at least Friday. A positively tilted trough develops into
a closed low over western WA/OR tonight before swinging across the
northern Great Basin through Monday. The next closed low reaches
western WA late Monday night. The surface low rapidly develops as
it approaches the central OR coast this evening with heavy precip
tonight along western OR into far northern CA where snow levels
will range from 2000ft in the north to 3500ft in the south. Those
levels drop tonight as rates drop into the light to moderate
range. Day 1 snow probabilities are moderate for over 8" from the
southern WA Cascades to the Klamath Mtns of CA and the
northern/central Sierra Nevada with high probabilities for over
12" for the OR Cascades.

Continued light to moderate precip with snow levels of 1000 to
1500ft is expected across the Pacific Northwest for Days 2/3 with
a continued focus on the OR Cascades. Snow probabilities for over
8" are moderately-high over the OR Cascades.


Northern Rockies through the Northern Plains...
Days 1-3...
As this main system moves east Monday, accumulating snows are
likely to reach down into the valleys of southeastern Washington,
eastern Oregon, and Idaho, with heavy accumulations possible for
the Blue Mountains into the northern and central Rockies from
central Idaho and western Montana to Utah on Monday into early
Tuesday. Snow will develop east of the Divide across the northern
High Plains Monday night into early Tuesday. Increasing upslope
flow on the northwest side of a low moving east of the Rockies,
along with divergence aloft near a coupled jet, will support heavy
snows developing over the central to western Montana ranges Monday
night into Tuesday.

Heavy snow will rapidly develop and spread east from central
Montana into parts of the Dakotas starting late Monday night. As
the leading low continues to track east, strong low-to-mid level
frontogenesis on the northwest side of a powerful, deepening
surface low that is expected to track northeast from the central
High Plains to the Upper Midwest, overlapped by coupled upper jet
forcing, will support heavy snow developing across the region.
Model spread remains, though mostly with the pivot of the low over
MN late Wednesday into Thursday. Confidence has further increased
for heavy snowfall accumulations and strong winds to impact much
of southeastern Montana, northwestern South Dakota and
southwestern to central North Dakota into Wednesday. WPC snow
probabilities continue to indicate that through Wednesday
widespread accumulations of 8-12" are expected, with locally
heavier amounts to 2', particularly in western ND. Snow continues
Wednesday night mainly over ND/northern MN as the low tracks up
MN.
    

...Northern Minnesota...
Day 1...
A shortwave moving east over the north-central Plains to MN rest
of this afternoon closes into a low over central MN this evening
and tracks over the Arrowhead late tonight. This dynamic system is
expected to support rain changing to snow across northern
Minnesota later tonight with a burst to a few inches likely. Day 1
probabilities for over 4" are low to moderate over interior
Northeastern MN.


For Days 1-3, the probability of at least 0.1" icing is less than
10 percent.


~~~Key Messages for April 11-14 Blizzard~~~

--A long duration, significant winter storm will bring heavy snow
to the Cascades through Monday, then the northern Intermountain
West through the northern Plains Monday night into Thursday.

--A combination of heavy snow and strong wind gusts are likely to
produce blizzard conditions from the eastern slopes of the
northern Rockies across the northern Plains.

--Heavy snow combined with strong winds has the potential to
produce power outages, tree damage, hazardous to impossible travel
conditions, and impact livestock, especially calves and lambs.

--Prepare now for impactful winter weather and hazardous to
potentially impossible travel conditions.


Jackson