Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
347 AM EST Mon Dec 11 2023

Valid 12Z Mon Dec 11 2023 - 12Z Thu Dec 14 2023


...Interior Northeast...
Day 1...

Amplifying, negatively-tilted trough lifting north from the
Mid-Atlantic spurs continued rapid deepening of surface low
pressure as it tracks north over eastern New England this morning.
A strong NW-tilted FGEN band will continue to lift north on the
west side of the precip shield from the central Mid-Atlantic
through interior New England will continue to support snow rates
of an inch or so per hour (per 00Z HREF probs). Day 1 WPC snow
probabilities for an additional >6" after 12Z are moderate
(40-70%) for the Greens, Whites, and the western international
border with Maine.

Lake effect snow in typical northwest flow snow belts off Erie and
Ontario will persist today before shifting westerly tonight with
additional accumulation of a few inches in the Tug Hill.


...Michigan U.P. into the Tug Hill...
Days 2-3...

Upper low will move from northern Manitoba across far northern
Ontario through Tuesday with the associated surface cold front
dropping through northern MN today, the western Great Lakes
tonight and eastern Great Lakes Tuesday. 850 temps will be notably
colder with this wave, dropping to around -12 to -15C (into the
DGZ) and supporting WNW to ESE bands post-FROPA tonight on the
U.P. and off Lake Ontario Tuesday night before slowly diminishing
into Wednesday. Day 2 WPC probabilities for >4" are moderate to
high (40% to 80%) in eastern sections of the U.P. shoreline of
Superior. 

On Day 3, wind will veer from SW to W to WNW, favoring a
resurgence in lake effect single-band snow east of Ontario into
the Tug Hill as the cold front from the central Great Lakes passes
through. Day 2.5 WPC probabilities for >4" of snow are high (>80%)
in the Tug Hill.


...Southern Rockies...
Day 3...

A shortwave trough over western WA this morning gets ducted under
an amplifying northern stream ridge over western Canada through
tonight, with an arriving southern stream portions of the ridge
sending the trough south over Great Basin Tuesday. This trough
develops into an upper low over Arizona Tuesday night and becomes
cutoff, drifting east across New Mexico then through Thursday.
Gulf moisture shifts through west Texas in earnest by Tuesday
night with rain breaking out over the southern High Plains and an
easterly component sending it up the eastern slopes of the
southern Rockies (mainly the Sangre de Cristos Wednesday. Height
falls from the approaching upper low and ample moisture set up a
terrain based heavy snow case for the southern Rockies later
Wednesday into Thursday. Day 3 snow probs for >4" are moderate
(40-60%) over the NM side of the Sangre de Cristos over through
Raton Mesa with more to fall into Thursday.


Jackson