Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
343 PM EDT Wed Apr 13 2022

Valid 00Z Thu Apr 14 2022 - 00Z Sun Apr 17 2022

...Northern Plains/Upper Midwest...
Days 1-2...
...Significant and potentially historic blizzard continues for
portions of the Northern Plains...
Blizzard conditions will persist across portions of North Dakota
and eastern Montana as a strong closed low drifts east across the
northern Plains tonight and into the Upper Midwest on Thursday. In
addition to strong and gusty winds, moderate to heavy snows will
focus on the west side of a potent surface-to-low level wave. This
wave is forecast swing eastward from eastern North Dakota toward
northern Minnesota. A quick changeover from rain to snow is also
likely across far northern Minnesota underneath a mid-level low.
Sufficient divergence near the left exit region of a strong
upper-level jet will support snowfall rates around 1" per hour and
the chance for moderate accumulating snow along the
Minnesota-Canada border. WPC probabilities indicate that
additional snow accumulations of 8 inches or more are possible
(30-40%) across portions of north-central and northern North
Dakota, as well as far northern Minnesota.  On Thursday, generally
light wraparound snow is expected to shift east, with a few inches
likely across northern Minnesota. Guidance also depicts a few snow
squalls are possible within an area of steepening lapse rates
south of the main low pressure center on Thursday from the Dakotas
across southern Minnesota and into northern Wisconsin. Snow will
continue to wane and winds subside as the low lifts farther
northeast across Canada and high pressure settles into the
northern Plains Friday into Saturday. 

...Pacific Northwest and Northern California to the Northern
Rockies...
Days 1-3...
An upper low in the southeastern portion of an omega block will
remain in place over the Northwest, maintaining a cold and
unsettled pattern across the region. A series of shortwaves moving
through the broader scale flow will support periods of organized
precipitation, producing locally heavy amounts including areas of
heavy mountain snow.  Locally heavy accumulations are expected for
the southern Oregon and far northern California mountains tonight
into Thursday.  With snow levels remaining low, additional light
accumulations can be expected across the Oregon lowland areas.
Models show a relative break for most areas early Friday before
another shortwave moves into southwestern Oregon and Northern
California by early Saturday. Southwesterly flow ahead of the
system will increase snow levels on Friday before it moves inland
and towards the Northern Rockies on Saturday.

For Days 1-3, the probability of 0.10 inch or more of ice is less
than 10 percent.

Snell


~~~Key Messages for April 13-14 Blizzard~~~

--Blizzard conditions will continue to impact portions of the
northern Plains into Thursday.

--The combination of heavy snow and strong wind gusts will produce
dangerously low visibilities, with significant blowing and
drifting of snow.

--Travel will remain difficult to impossible, and widespread power
outages and tree damage are expected. Significant impacts to
livestock are also possible.

--Snowfall intensity will diminish by Thursday, with additional
accumulations up to a foot. Maximum storm total snowfall of three
feet is possible in parts of eastern Montana and western and
central North Dakota.