Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
428 AM EDT Mon Oct 01 2018

Valid 12Z Mon Oct 01 2018 - 12Z Thu Oct 04 2018


Day 1...

The probability of significant icing and/or snow is less than 10
percent.

Day 2...

...Northern Rockies...
Models continue to show a well-defined shortwave trough digging
south through British Columbia on Tuesday before pivoting
southeast across the Pacific Northwest into the northern Rockies
late Tuesday into early Wednesday.  This will bring the threat for
heavy snow south along the Canadian Rockies into northwest Montana
by Tuesday night, with models continuing to signal the potential
for heavy accumulations by Wednesday morning across portions of
Glacier National Park.  WPC Day 2 probabilities (ending 12 UTC
Wed) show a moderate risk for accumulations of a foot or more
across the higher elevations within the northern portion of the
park.

The probability of significant icing is less than 10 percent.

Day 3...

...Sierra...
An upper low dropping south along the California coast on Tuesday
into early Wednesday is expected to move inland Wednesday night -
producing some high elevation snow across the Sierra.  WPC
probabilities show some chance for accumulations of 4 inches or
more, mainly for elevations above 9000 ft.

The probability of significant icing is less than 10 percent.

Pereira