Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
316 AM EST Thu Nov 24 2022

Valid 12Z Thu Nov 24 2022 - 12Z Sun Nov 27 2022

...Southeast Colorado to West Texas...
Days 1-2...
A digging shortwave over the Four Corners region this morning will
continue to amplify, with a closed low expected to develop and
deepen over New Mexico later this morning before settling south
over northern Mexico by early tomorrow.  Models continue to
advertise an anomalously deep system, with the consensus
indicating heights more than 2 standard deviations below normal
across far West Texas later today.  Broad scale ascent afforded in
part by favorable upper jet forcing, along with deepening
moisture, will help foster the development of widespread
precipitation from the southern Rockies into the High Plains. 
Overnight, the general model trends continued to move toward a
slower solution - paring back amounts some across the southern
High Plains, while bolstering amounts a little across some of the
southern New Mexico-West Texas mountains.  Overall however, models
continued to focus on two areas of heavier snow accumulations. 
The first is along the eastern slopes of the Sacramento,
Guadalupe, and Davis mountains, where upslope flow is expected to
accentuate the potential for locally heavy amounts.  WPC PWPF
shows moderate to high probabilities for storm total amounts
exceeding 8 inches from the eastern slopes of the Sacramento and
Guadalupe mountains into the adjacent high terrain.  A second area
of potentially amounts is expected to set up farther east over
southeastern New Mexico into western Texas.  Probabilities for
storm totals exceeding 8 inches have increased over portions of
the east-central to the southeast plains of New Mexico, where a
slow-moving deformation band may produce a swath of heavy wet snow.

...Pacific Northwest...
Day 3...
A threat for heavy mountain snow is expected to return to the
Olympics and northern Cascades by the latter half of the weekend. 
Deep onshore flow and large-scale ascent ahead of a well-defined
shortwave diving southeast from the Gulf of Alaska is expected to
bring widespread precipitation into the region by Sunday.  Lower
snow levels will support accumulating snows at the Cascade passes,
with WPC PWPF indicating moderate to high probabilities for
accumulations of 4 inches or more at both Snoqualmie and Stevens
passes.

The probability of significant icing exceeding 0.1" is less than
10%.

Pereira