Bolaris: Expect more snow than thought

Ready for the cold, a man scurries down the 1600 block of Spruce Street on Thursday, Jan. 16, 2014, dodging snowflakes while carrying a hot beverage and wearing a polar bear hat. (Ed Hille/Staff)

Computer runs from overnight and this morning have sharply changed the outlook for snowfall in the Philadelphia region.

Originally, the storm system looked as if it would produce a couple of inches in town and 2-4-plus inches along the coast. That intensity and positioning of the storm, however, has changed dramatically.

It appears the snow will now intensify quite rapidly off the Delaware coast and not move out as quickly as first thought.

With polar air feeding the storm to the West, and the storm now tapping significant Atlantic moisture, snow amounts will exceed 4 inches throughout the region with the heaviest snow to fall across coastal sections of New Jersey.

This should be a quickly developing and all-out snow storm for us starting Tuesday afternoon.

The set-up:

-An Arctic front approaching from the west will come just as low pressure forms in the Tennessee Valley.  The rapidly developing system off Virginia will move up the coast to the northeast. The effect will be to spread snow Southwest to Northeast across the region by Mid-day Tuesday.

-The rate of snow will increase by the Tuesday evening rush. The snow will accumulate on roadways. Winds will increase. Temperatures and wind chill factors will drop.

-Timing: light snow arrives between 11 a.m. -1 p.m.  Tuesday. Most of the accumulating snow will fall between 1 p.m. and 11 p.m. with the heaviest during the evening hours.

-Snow will pull away during the overnight hours.

-By Wednesday morning, temperatures will plunge to single digits with some blowing and drifting of snow. Wind chill factors will reach sub-zero for everyone. Wednesday will remain bitter cold with temperatures only reaching the teens.

Expect 4 to 8 inches of snow for the city and across the Delaware Valley. New Jersey shore locations, especially Ocean and Monmouth can possibly get 6-10". That includes parts of Cape May County.

But a caveat that this is a quickly changing weather situation so I’ll pay close attention to the latest information because computer models have NOT handled this system well.

The snowstorm should reach from D.C. to Philly, and on into N.Y.C. and Southern New England.