Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
434 PM EDT Sun May 1 2022

Valid 00Z Mon May 2 2022 - 00Z Thu May 5 2022

...Pacific Northwest to the Central Plains...
Days 1-3...

The low pressure system currently crossing the Rockies will emerge
over the Plains Monday morning, and will likely result in at least
some snow across western and central portions of Nebraska, and
perhaps into southern South Dakota, as marginally cold air in the
deformation zone supports a rain to snow changeover where rates
are sufficient.  Although WPC probabilities for 4+ inches of snow
remain less than 10 percent, this may be underdone in a few cases
as some of the latest CAM guidance is more aggressive with heavier
snow.  The question will be how much can actually accumulate on
the ground.

Farther west, another closed low is forecast to move across the
Pacific Northwest on Monday, with high elevation snow for the
Oregon Cascades and the Blue Mountains, then across the central
Idaho ranges. More than 6 inches are likely for the higher
elevations of these areas, mainly above 8000 feet.  By Tuesday,
the upper low will move into the central Rockies with the 700mb
low traveling across Idaho into northwestern Wyoming.  From the
Bitterroots to the Big Belts and Absaroka Range, modest snow is
possible with WPC probabilities for at least 6 inches >40% between
days 2 and 3.

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

Hamrick/Pereira