Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
432 PM EDT Sat Apr 23 2022

Valid 00Z Sun Apr 24 2022 - 00Z Wed Apr 27 2022

...Northern Plains...
Day 1...

Mature cyclone will move through eastern ND into northwestern MN
overnight into tomorrow morning, with continued heavy snow on its
northwest side in a pivoting deformation band. Snowfall rates of
1-2"/hr are likely along the MT/ND border into northwestern ND for
the first half of the Day 1 period before tapering off quickly
Sunday afternoon as the system pulls away. A bit farther south,
upslope flow into the Black Hills will favor a secondary area of
maximum snowfall totals. Some light freezing rain is still
possible in the transition zone between the warm/moist air to the
east and the marginally cold air to the west/northwest. WPC
probabilities for at least 6 inches of additional snow are
moderate to high (>40% and >70%) over western North Dakota and
over the Black Hills. Low probabilities (10-40%) of at least 4
inches of snow extend across central and northeastern ND.

...Colorado...
Days 1-2...
Weak shortwave to the southwest of the more dominant cyclone to
the northwest will shear through Colorado Sunday into early
Monday. Enough moisture will be present to wring out several
inches of snow over the higher terrain of central CO down through
the CO side of the Sangre de Cristos. Higher snowfall in excess of
4 inches will be confined to areas above at least 7000ft.

...Pacific Northwest...
Day 3...
Upper low moving out of the Gulf of Alaska today will bring a cold
front and a weak surge of moisture to Washington and Oregon Day 3.
A few inches are likely above 5000ft and especially over the
higher peaks of the Olympics and Cascades but also into the Blue
Mountains in northeastern Oregon.


For days 1-3, the probability of significant icing greater than
0.25 inches is less than 10 percent.


...Key Messages for the Northern Plains Blizzard...

--A significant winter storm will continue to produce heavy wet
snow and strong winds through portions of the northern Plains into
Sunday.

--Heavy snow rates of 1-2"/hr will combine with strong and gusty
winds to produce blizzard conditions across portions of the
northern Plains through tonight. Total snow accumulations may
reach 2 feet.

--The blizzard conditions will create extremely limited visibility
at times. Travel will be very difficult to impossible, with
significant travel delays likely.

--The snow will be heavy and wet which may create power outages
and tree damage. Significant impacts to livestock are also
possible.


Fracasso