Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
330 AM EDT Wed Apr 26 2023

Valid 12Z Wed Apr 26 2023 - 12Z Sat Apr 29 2023

...Southern Colorado...
Day 1...

The upper low associated with the late season winter storm over
northeastern NM this morning will continue southeastward today,
with snow winding down from north to south. Several inches,
perhaps up to a foot, are likely over the Sange de Cristos and
over the Raton Mesa. WPC snowfall probabilities of at least 4
inches of snow are moderate (>40%) above 7000ft or so.

...Rocky Mountains...
Days 2/3...

A Pacific system entering northern British Columbia this morning
will dive southeastward into Montana by the start of Day 2 then
swiftly dig southward through the Rockies toward the Four Corners
by the start of Day 3. Surface front associated with the mid-level
vort (nearly closed off low) will plunge southward and
southeastward ushering in colder air and changing rain to snow
over many locations. Northerly to northeasterly flow post-FROPA
will favor Black Hills in SD but especially the Bighorns in WY
where more than six inches of snow is likely. Frontal passage
could mix down some windy conditions and combine with robust UVVs
into the DGZ for some bursts of snow Thursday evening. WPC
probabilities of at least 4 inches of snow are moderate (>40%)
over the Absarokas, Wind River Range, Bighorns, Laramie Mountains,
and the Black Hills.

Snowfall will quickly expand southward across Colorado as the
mid-level shortwave and surface front push through. Several inches
of snow are forecast for the CO Rockies with rain ending as some
snow down to around 5000ft. Favored areas will generally be above
7000ft where WPC probabilities are >40%. Snowfall will finally
move through the Sangre de Cristos and Raton Mesa into Day 3
before ending late Friday night.


The probability of significant icing greater than 0.25" is less
than 10 percent.


Fracasso