Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
420 AM EST Mon Feb 17 2020

Valid 12Z Mon Feb 17 2020 - 12Z Thu Feb 20 2020

...Great Lakes to the Northeast...

Phasing energy over the northern Plains and Upper Midwest is
expected to support a deepening surface wave lifting from the
lower Missouri valley northeastward into the western Great Lakes
on Monday.  Low-to-mid level frontogenesis along with favorable
upper jet forcing is expected to support a stripe of light to
moderate snows on the northwest side of the low track.  Overnight
HREF run indicates several members producing precipitation rates
of 0.05-0.1 in/hr hour translating east from the eastern
Iowa/Minnesota border into southern and central Wisconsin during
the day on Monday and then northeastward into eastern Upper
Michigan and northern Lower Michigan by the evening hours.  For
the 24-hr period ending 12Z Tue, WPC PWPF shows high probabilities
for amounts of 4-inches or more across portions of central
Wisconsin to eastern Upper Michigan and northern Lower Michigan.

Models show the low moving across northern Lower Michigan Monday
night and then into southern Ontario by late Tuesday morning. 
Warm advection precipitation will spread quickly east from the
Great Lakes across the Northeast on Tuesday.  With high pressure
over the Northeast moving rapidly offshore, thermal profiles
continue to show some snow at the onset before changing to rain
across much of northern Pennsylvania, western to southern New York
and southern New England.  Farther to the north however, expect
snow to remain the dominant precipitation type, particularly from
the Adirondacks into northern New England, with at least a few
inches likely along the favored terrain.  For the 24-hr period
ending 12Z Wed, WPC PWPF shows high probabilities for amounts of
4-inches or more across the Tug Hill and southern Adirondack
region in New York and then from northern New Hampshire across
much of central and northern Maine.

...Central Rockies and High Plains...
Low level wave development associated with a positively-tilted
upper trough dropping southeast across the northern to central
Rockies will increase upslope flow and low level convergence from
the central High Plains into the mountains of eastern Colorado. 
This is expected to produce some light snows across portions of
western Nebraska and Kansas and eastern Colorado, with locally
higher totals along orographically favored areas of the Sangre de
Cristo Mountains late Wednesday into early Thursday.

For Days 1-3, the probability of significant icing (0.25-inch or
greater) is less than 10 percent.

Pereira