Bolaris: Old Man Winter to drop bombogenesis

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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)

BOMBOGENESIS (a rapidly intensifying storm) will take place Tuesday afternoon off the Virginia coast.

Computer models had an extreme reversal on the intensity and track of this storm over the last 24-36 hours, and that's why snow amounts were jacked up Monday as computer models came late to the snow party.

Hinting started to take place late Sunday as my forecast called for a significant storm for some with 4+ inches of snow possible across parts of New Jersey. But a big uptick in moisture being fed into the storm combined with a piece of the polar vortex sending another package of severe cold. This time, it gets pulled into the storm's circulation leading to rapid intensification and high snow ratios.

Normally we receive a 10-1 ratio, with one inch of liquid equaling 10 inches of snow, but in this case we have an overall ratio of 13-1, to as much as 15-1, meaning more snow with less liquid.

The set-up

A weak storm will move into the Tennessee Valley Tuesday morning, marking the leading edge of the arctic outbreak. As that one weakens, another storm develops and intensifies rapidly off the Virginia coast, spreading snow, heavy at times with increasing wind and falling temperatures. Temperatures by Wednesday morning will be in the single numbers with wind chills 10-15 below zero. Plenty of blowing and drifting of snow. Dangerous cold.

Timing

Snow will overspread the region shortly after the morning rush.

Noon-3 p.m.: It starts to accumulate, including roadways.

3-8 p.m.: The brunt of accumulating snow, heavy at times, blowing and drifting. The impact? Hazardous driving and major travel troubles, including in the air, railways and any form of mass transit.

8 p.m.-midnight: The heaviest of snow is moving out, but still snowing and accumulating.

Midnight-3 a.m.: The snow is moving out, but severe cold, blowing and drifting will make for extreme travel conditions. Stay home!

Potential snow totals

Philly, 7-11 inches

Camden, 7-11 inches

Delaware County, 7-11 inches

Chester, Montgomery and Bucks counties, generally 6-10 inches

Berks County, 4-6 inches

Lancaster County, 6-10 inches east/4-8 inches western side

Salem County, 7-11

Jersey Shore, 6-10 inches

Northern Ocean and Monmouth counties -  8-12 inches

Northern Delaware - 7-11 inches

Central and southern Delaware, 6-8 inches

Lehigh Valley, 4-6 inches

Poconos, 2-4 inches

Baltimore, 6-8 inches

Washington, D.C., 5-8 inches

New York City, 6-9 inches

Eastern Long Island, 8-12 inches

Boston, 6-9 inches

Capes of southeast Massachusetts, 10-14 inches

Shores of Connecticut, 6-9 inches

John Bolaris