Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
450 PM EST Mon Jan 28 2019

Valid 00Z Tue Jan 29 2019 - 00Z Fri Feb 01 2019



...Lower Mississippi Valley to the Mid Atlantic...

A strong cold front associated with the large amplifying upper
trough in the East is forecast to push southeast into the lower
Mississippi valley overnight.  A well-defined shortwave moving
through the base of the trough, along with left-exit region upper
jet forcing is expected to support post-frontal precipitation,
with rain changing to snow from Louisiana eastward into central
Mississippi overnight before shifting farther east across northern
and central Alabama into the southern Appalachians around
daybreak.  WPC probabilities show 1-2 inch snow accumulations
likely from northern Louisiana to the southern Appalachians, with
the potential locally heavier amounts of 4 inches across portions
of the region.

Farther to the north, rain changing to snow, with generally light
accumulations is expected across the central Appalachians Tuesday
morning.  To the east, expect the changeover to occur later during
in the day, resulting in some light accumulations but with
potentially significant impacts along the central to northern
Mid-Atlantic I-95 corridor during the afternoon and early evening
hours.  

...Northeast...

As the previously detailed front pushes east into the
Mid-Atlantic, low pressure developing along the front is expected
to accentuate amounts to the west as it lifts northeast from the
northern Mid-Atlantic into New England Tuesday evening.  Portions
of eastern Pennsylvania into the Catskill region of Upstate New
York may see significant snow accumulations by Tuesday evening,
with WPC probabilities indicating a High Risk for amounts of 4
inches or more on Day 1. 

This wave will continue to lift north through the evening and
overnight to the northern New England Coast Wednesday morning,
supporting significant snow amounts across portions of interior
central and northern New England.  WPC probabilities indicate that
accumulations of 6 inches or more are likely across a good portion
of northern Vermont, New Hampshire and Maine during the Day 2
period.

...Great Lakes...

Lake effect snow showers will resume in earnest in the lee of the
upper lakes as the deep low over central Canada drops southeast
into the region on Wednesday.  Strong backing winds on the
backside of the system will support heavy totals across portions
of the U.P. and northern L.P. of Michigan.  Westerly winds will
support heavy totals farther south as well along the eastern
shores of Lake Michigan.  Periods of snow are expected to continue
to impact portions of Michigan through Wednesday before waning on
Thursday.  Meanwhile, strong west-southwesterly to westerly winds
will support lake effect snow showers with locally heavy totals in
the lees of lakes Erie and Ontario Wednesday into Thursday.

...California...

A compact upper low dropping southeast from the eastern Pacific
into Southern California is expected to produce some locally
heavy, high elevation snows along the Sierra on Thursday.

The probability for significant icing is less than 10 percent
nationwide days 1-3.

Pereira