Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 PM EDT Sat Mar 16 2024

Valid 00Z Sun Mar 17 2024 - 00Z Wed Mar 20 2024

...Four Corners States
Day 1...

The primary mid-level low over the Desert Southwest will continue
to be the main driving factor for widespread precipitation over
portions of the Southern Rockies and Four Corners region through
Sunday. Confluent flow east of the cutoff low will provide
sufficient moisture, though the intensity of the precipitation is
expected to wane later today/tonight as the energy fills and
gradually weakens into late Sunday.

Snow levels of 7000-8000 ft will continue over the San Juans and
Sangre de Cristos before dropping to around 6500 ft tonight as the
low wobbles east. The latest snow probabilities for 8" are moderate
to high (40-80 percent) and localized totals above 12" are possible
(20-40 percent) for the San Juans. By Sunday, surface high pressure
moving down through the Plains will push the precipitation over
central New Mexico where snow probabilities for 8" are moderate to
locally high (40-70 percent) over the southern Sangre de Cristos
over to the San Mateo Mountains.

Low pressure lingers over AZ probably through Tuesday, but the
moisture focus shunts farther south as the surface high plunges
down the Plains that by Monday morning, leading to only lighter
precip over southern NM/AZ.


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

Digging shortwave trough will advance eastward through Ontario
tonight, reaching Quebec and Maine by Sunday. This feature will
push a strong cold front through the region tonight across the
Great Lakes and then through New England Sunday/Sunday night. Along
and ahead of it, thermal profiles are warm enough to be mostly a
rain event across the eastern Great Lakes and Northeast except for
the far northern areas of New Hampshire and northern Maine where
residual cold air would be supportive of a mix of rain and snow. As
the low pressure occludes over northern Maine and colder air
begins to wrap into the system, a changeover to more snow is
expected.

Meanwhile, the strong cold air advection in the wake of the frontal
passage and much lower heights with the trough axis overhead will
bring a period of significant snowfall accumulations to the favored
N/NW snow belt areas of the U.P. of Michigan where the latest 4
inch snow probabilities for Day 1 are between 40-80%. Localized
6-10" totals are possible (10-30%).

The focus shifts to the eastern Great Lakes Monday as another
reinforcing shot of colder air arrives. Here, the snow
probabilities for 4 inches are between 30-60% above Erie, PA,
along the Chautauqua Ridge, and Tug Hill Plateau.

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


Taylor