Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
410 AM EDT Fri Oct 19 2018

Valid 12Z Fri Oct 19 2018 - 12Z Mon Oct 22 2018


Day 1...

The probability of significant snow (4 inches or more) is less
than 10 percent.

The probability of significant icing (0.25 inches or more) is less
than 10 percent.

Day 2...

...Central Appalachians...
A clipper swinging around the Great Lakes Saturday crosses the
central Appalachians Saturday night. Continental air, enhanced
with Great Lake moisture will lift over the Allegheny Plateau with
a saturated layer into the dendritic snow growth zone for a few
hours. Wet bulb zero levels from NAM/GFS soundings suggest snow
levels around 1500ft with moderate percentages for 4 or more
inches above about 3000ft in WV. A sharp cutoff in precipitation
is expected as usual to the east of the Allegheny Front. Ridging
quickly builds in Sunday making for only a short window for snow
during Saturday night.

The probability of significant icing (0.25 inches or more) is less
than 10 percent.

Day 3...

...Four Corners...
A cutoff upper low drifts east from CA Sunday. Southwesterly
southern stream flow south of the low will bring eastern Pacific
moisture into UT/AZ. High mountain snows with low probabilities
for four inches are on tap for the highest Uinta and Wasatch
mountains Sunday night.

The probability of significant icing (0.25 inches or more) is less
than 10 percent.

Jackson