Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
420 PM EDT Thu Mar 14 2019

Valid 00Z Fri Mar 15 2019 - 00Z Mon Mar 18 2019


...Great Lakes...
A cold front moves east across the upper lakes tonight. 
Post-frontal cold advection develops, with continuing high
relative humidity and low level convergence in the lee lake shore
areas of the UP of MI supporting lake enhanced snow showers
overnight.  Fri morning, the air mass gets cold enough for snow
showers to develop off Lake MI into western lower MI. Slightly
higher amounts are expected in the UP due to longer duration snow
in the day 1 period.

Fri evening, the cold front progresses east across the lower
lakes, with post-frontal cold advection supporting snow showers in
the lee of lakes Erie and Ontario.
During Saturday, the boundary winds veer to the west, supporting
long cross-lake Ontario fetches and upslope flow into the Tug Hill
plateau.  Snow showers taper in the lee of Lake Superior as drier
air aloft advects east from the upper MS Valley as a ridge
approaches.

On Day 3 Sat night to Sun, as the ridge moves east across the
lakes, drier air aloft continues to filer east from the upper to
the lower Lakes. Snow shower coverage/intensity should wane as a
result of decaying low level convergence and lack of available
moisture aloft.

...Southern Rockies...

The models continue to show a 700 mb wave drifting south across NM
tonight, with pockets of enhanced layer humidity and 700 mb
ascent, leading to light snow in the ranges of central to eastern
NM. As the 700 mb trough and embedded low drifts southwest Fri,
drier aloft advects down from CO, so activity should decrease in
coverage/intensity from north to south.

On day 3, the probability of 4 or more inches of snow is less than
10 percent.

The probability of significant freezing rain is less than 10
percent.

Petersen