Tuesday Discussion : Winter Weather Whiplash

It’s not even mid December… and we’ve got our 2nd complex winter weather event to decipher.

Timing:
– Through 6pm : Periods of rain showers (turning colder in PM)
– 6pm to 12am : Rain changes to wet snow from NW to SE
– 12am to 9am : Bands of wet snow possible (especially South of I-84 & east of the Hudson River)

Impact:
– Flash freeze possible.  Temps near 50° at 12pm … near 32° at 12am
– Icy roads and untreated surfaces likely, as moisture may freeze before it evaporates
– Wet snow possible, accumulation likely where it occurs.  Snow covered and icy roads possible

Snow Accumulation:
– NW HV (Zone 1, 2, N3, N4, 5 & 6) : Coating to 1 inch
– SE HV (Zone S3, S4, 7, 8) : Coating to 2 inches
– Extreme SE HV (Zone 9) : Coating to 3 inches

So… we’ve got a wild weather ride over the next 24 hours, and even as of this post… it may all come down to a bit of luck, in determining whether we see a slushy coating, or 2 or 3 inches of wet snow tonight.
 
— The Setup —
An extended frontal boundary runs from Maine into the Gulf of Mexico. This boundary is slowly pushing eastward. At the same time, a digging trough is pushing cold air back toward the Hudson Valley. So these mild morning temps will be tumbling this afternoon.
 
There is another wave of energy in the Tennessee Valley that will travel NE along the boundary tonight. This energy should generate upward motion, which will cause precipitation to develop and enhance as it moves NE. The precipitation will run into colder air, and transition to wet snow overnight.
 
— The Question —
The band of snow that develops is likely to be 100 to 200 miles wide, and develop at the same time as rain is changing to wet snow. The position of the boundary at that time will determine if the snow falls in the Hudson Valley, or just to our SE. Instead of this energy digging and intensifying, it’s stretched out, making it harder to determine where the snow band will develop. It’s very likely that this uncertainty will exist until the event begins to unfold.
 
— The Forecast —
This is why our forecast calls for as little as a coating in all areas. Because we have data that suggests this stays almost entirely southeast of the Hudson Valley. But we also have data that suggests 2 or 3 inches could fall in portions of the area. For that reason, we have staggered the snowfall forecast with the higher potentials being the further south and east you go. However, it’s also a very real possibility, that this band forms when it’s still 34 degrees, and much of it falls as a rain/snow mix… keeping accumulations at a coating or less. So to recap:
– Catskills & Northern HV : coating to 1 inch
– Mid & Lower HV : coating to 2 inches
– Extreme Lower HV (Zone 9) : coating to 3 inches
 
We’ll monitor this as the afternoon progresses, to see if we need to update this at all. Stay warm… because temps will tumble from near 50° at noon… to the mid and upper 30s by dark… and that NW wind could be rather gusty. Have a nice afternoon Hudson Valley!

5 thoughts on “Tuesday Discussion : Winter Weather Whiplash

  1. I think this will also be the 4th arctic blast we have had since early November. Why is the intense winter weather hitting so early? And is this pattern here to stay through winter?

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