Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
324 PM EDT Sun Mar 17 2024

Valid 00Z Mon Mar 18 2024 - 00Z Thu Mar 21 2024

...Four Corners States...
Day 1...

The cutoff closed mid-level low over Arizona will continue to
bring precipitation including higher elevation snowfall to portions
of Arizona and New Mexico through Monday as confluent flow east of
the cutoff low pulls moisture into the region and sufficient
forcing for ascent remains. Though as the cutoff low weakens/fills
by the beginning of Day 2, precipitation intensity is expected to
diminish and gradually give way to just additional light snowfall
accumulations. Snow levels will continue to be around 6000-7000 ft
through Day 1. The latest snow probabilities for 6" are between 30
and 60 percent for the terrain areas, where some localized totals
near 10 inches will be possible at the highest peaks.


...Great Lakes and New England...
Days 1-3...

A strong digging shortwave trough and associated cold front is
advancing quickly across the Great Lakes today and is characterized
by anomalously low heights (500 mb heights -2 sigma) and 850 mb
temps nearing -2 sigma as well by tonight. Impressive cold air
advection over the Great Lakes is producing scattered to numerous
precipitation showers which will lead to accumulating snow for the
favored N/NW snow belt areas off Lake Superior in the U.P. of
Michigan, western L.P. Michigan, and across western NY off Lakes
Erie and Ontario. Day 1 snow probabilities are 30 to 50 for 4
inches although the 4" probabilities are above 80 percent in the
Tug Hill Plateau in Upstate NY where Day 1 totals are likely to
exceed 6-8 inches.

A secondary/reinforcing shortwave trough is then expected to move
through the Great Lakes late Wednesday into Thursday. This will
drive another round of lake effect snow, particularly for the
eastern Great Lakes but also some minor accumulations for interior
Northeast locations and the upslope region of the central
Appalachians. The latest WPC snow probabilities for 4 inches on Day
3 are 30 to 50 percent off Lake Erie and are high (>70%) off Lake
Ontario. 3-day snowfall totals may approach 10-12 inches for the
favored snow belt areas off Lake Erie and Lake Ontario while the
Tug Hill Plateau may top 2 feet through mid/late week.


The probability of receiving at least 0.1" ice is less than 10%
across the CONUS through Day 3.


Taylor