Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
355 PM EDT Tue Oct 22 2019

Valid 00Z Wed Oct 23 2019 - 00Z Sat Oct 26 2019

...Rocky Mountains...
Days 1-3...

Mid-level trough will dig southward through the Mountain West
through Thursday. Guidance is in good agreement with this trough
amplifying the first 48 hours, but significant discrepancies exist
thereafter. The Non-NCEP suite closes off the low across the
NM/TX/OK, while the GFS/NAM is much more progressive with a trough
racing eastward towards the Plains/Great Lakes. While there is
lowered confidence by day 3, the current preferences are for the
slower, more amplified solution of the ECMWF/UKMET/CMC.

This suggests increasing snow chances in the high terrain of the
Northern Rockies on D1, before snow probabilities ramp up into the
Central Rockies of CO and into NM D2/D3. This is in response to
jet level diffluence within strongly coupled jet streaks, upslope
enhancement behind a cold front dropping into TX/NM, and Pacific
Moisture riding atop driving isentropic ascent as well. The best
chances for heavy snow should be focused in Colorado  where the
best overlap of forcing and moisture coexist, and snow levels drop
to 4000 ft. Here, WPC probabilities are high for 8 inches in the
highest terrain of the Rockies and Sangre De Cristos, with low
probabilities for 4 inches extending into the High Plains.

Although confidence decreases into D3 due to the position of the
upper low, there is potential for some light accumulating snow
into the Sangre De Cristos and Sacramentos of New Mexico, but if
the further east solution verifies for the mid-level energy, these
amounts would likely lower.

The probability of significant icing is less than 10 percent.

Weiss