Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
206 PM EDT Sun Apr 12 2026

Valid 00Z Mon Apr 13 2026 - 00Z Thu Apr 16 2026

...Northern/Central Rockies...
Days 1-2...

An approaching upper trough and broad southwesterly flow will
allow light to moderate snow to spread across the Great Basin and
northern Rockies tonight through the day on Monday. By Tuesday,
trailing vorticity on the southwest side of this trough will move
into the Four Corners, enhancing snowfall more broadly over the CO
Rockies, including the Wasatch, Uintas, and especially the San
Juans in southwest CO. Snow levels initially around 8000-9000ft
will fall to around 7500ft by later Tuesday and early Wednesday as
most of the snow ends from west to east. WPC probabilities for at
least 6 inches of snow are >50% above about 8000ft over eastern OR
into the central ID ranges due to the lead upper trough into
Monday, and above 10,000-11,000ft into the Wasatch, Uintas, and San
Juans.


...Pacific Northwest/Northern Rockies...
Day 2-3...

Initial troughing over Alaska will steadily move southeastward
along the BC coast through Tuesday, bringing a 105kt jet into
western WA. A modest surge of moisture along/ahead of the cold
front (IVT values around the 90th percentile for mid-April) will
support widespread rain and mountain snow starting around early
Tuesday and continuing into Wednesday. Snow levels initially around
3000ft (Cascades) to 4000ft (Northern Rockies) will fall to around
1500-2000ft in the Cascades as much colder air works in from the
northwest by 12Z Wednesday and especially by 00Z Thursday (700mb
temperatures dropping to around -15C). Though precipitation may
start as rain, snow will quickly become the dominant p-type for
most passes. Some of this snow could even become significant at
higher passes, including Snoqualmie Pass and Washington Pass.
Through 00Z Thursday, WPC probabilities for at least 6 inches of
snow are >50% above about 2500ft in the Cascades and 5000-6000ft in
the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller