Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
442 PM EDT Mon May 13 2019

Valid 00Z Tue May 14 2019 - 00Z Fri May 17 2019


...Northeast...
Days 1-2...

A closed upper low with anomalously low heights will support late
season snows across interior portions of the Northeast beginning
late Monday and continuing into Wednesday.

Rain changing to snow can be expected across some of the higher
elevations of the Catskills, Adirondacks and northern New England
ranges tonight through Tuesday as a closed low, carving out 500mb
heights 1 to 1.5 standard deviations below normal, moves east from
the eastern Great Lakes  tonight. Moderate Day 1 probabilities for
six inches are over the higher Adirondacks, Green, and White
Mountains. The greatest potential for significant accumulations
remains centered along the northern White Mountains, particularly
across the Presidential Range, where WPC guidance is moderate for
12 inches.

As a coastal low deepens over Nova Scotia, precipitation is
expected to continue across northern New England, with additional
snows likely for portions of the northern White Mountains, while
extending north into northern Maine during the overnight period
Wednesday night into early Thursday.


...California...
Day 3...

A trough approaching the West Coast Wednesday closes Wednesday
night before reaching the northern CA coast Thursday morning. A
plume of one inch plus precipitable water comes ashore late
Wednesday and Wednesday night with heights/snow elevations falling
over higher CA terrain under the low on Thursday. Heavy snow is
expected during the day Thursday above about 6500ft on the Sierra
Nevada and the CA Cascades/highest Klamath Mtns where there are
moderate probabilities for a foot of more above about 7000ft.


The probability of significant icing is less than 10 percent.

Jackson