Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
249 PM EST Sat Jan 22 2022

Valid 00Z Sun Jan 23 2022 - 00Z Wed Jan 26 2022

...Southwestern U.S...
Day 1...

Deep closed low over southern Arizona crossing into northwestern
Mexico will gradually turn east tomorrow and slowly weaken into
far west Texas late on day 1. Limited moisture will be enhanced by
upslope/convergent flow into the Mogollon Rim to produce a few
inches of snow over the higher peaks with some areas seeing over 4
inches.

...Upper Midwest/Great Lakes...
Days 1-3...

A series of shortwave troughs embedded within the larger scale
cyclonic flow present over the Great Lakes region will bring a
couple rounds of accumulating snow to the Upper Midwest into the
Northeast. The first clipper, currently dipping southeast through
the northern Plains, will take on a Sioux Falls to Indianapolis to
Baltimore track through tomorrow evening. The overlap of best
forcing/lift within the DGZ will bring a corridor of fluffy snow
north of the low track across northeast Iowa, much of northern
Illinois, northern Indiana into portions of Ohio and western
Pennsylvania. The 12Z guidance trended a bit stronger with the
forcing with upwards of 0.25" (locally 0.30") liquid and with the
cold airmass and lift in the DGZ, SLRs near 20:1 will be common.
This supports 2-5" with localized 6" totals possible, particularly
across northern IL, northwest IN. This is where the latest WPC
probabilities for 4 inches have increased to near 60 percent.

The second clipper is quick to follow and moves through the flow
late Sunday through Monday night. A track slightly north of the
initial/first clipper and perhaps not as a strong, a stripe of a
few inches is likely across Wisconsin, far northern IL/IN, much of
southern Michigan, and northern Ohio. SLRs were also adjusted up
closer to 20:1 within the axis of best forcing. The clipper then
lifts through the Northeast and New England where a few inches
will be possible, favored downwind of Lake Erie and Ontario as
well as the terrain areas of VT/NH.

Combined totals over the next 3 days could exceed 6-8" across
northern IL to northern Ohio with the best potential for localized
12 inches off Lake Michigan of northwest IN and southwest MI.

...Northern to Central Rockies...
Days 2-3...

Fast moving and compact shortwave trough will dip southward out of
western Canada through the Rockies late on day 2 through day 3.
Limited but enhancement due to upslope will squeeze out a few
inches across the higher elevations and north-facing slopes of
central Montana on day 2 then spread southward through Wyoming and
the Colorado Rockies on day 3. The greatest WPC probabilities for
4 inches are across south-central Montana with just a slight
signal for WY and CO mountains.


The probability of significant icing is less than 10 percent.

Taylor