Winter Storm Threat: Dec 7-8 (first call)

Think 10/29 redux, only the temps and QPF line up a bit better for the changeover on the back-end:

 
The upper-level vort. max is potent enough to create an area of strong dynamics along the back edge of the system, which will pull cooler air down to the surface and make it cool enough within the boundary layer for some accumulation as the coastal low forms and tracks northeastward. Some banding will allow for locally higher totals along the axis that has the greatest snowfall through the WV/VA mountains, south-central and eastern PA and northern NJ.

I took the 12z Euro Op. solution and shifted the low center northwestward to account for for some model biases, which actually lines up fairly well with the 18z NAM after that adjustment. I believe the 12z and now 18z GFS solutions are too suppressed with this system given how strong the vort. max is.

The snowfall totals could go up as the storm’s track and QPF amounts get honed in on the models.

Snowfall is expected to start in the mountains of southern WV/VA/NC Wednesday evening, working into the DC region Thursday morning and departing the PA/NJ region Thursday afternoon.


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