Afternoon Zones: Significant snow likely on Thursday

Significant snow is expected on Thursday, as a low pressure system moves from the Mid Atlantic to a position east of the New Jersey coast. The low pressure system will deepen rapidly, as a result of increasingly favorable dynamics in the atmosphere’s mid and upper levels. As the storm moves off the coast of New Jersey, bands of very heavy precipitation are expected to rotate inland, resulting in widespread heavy snow.

The event will begin as mixed precipitation, especially in Southeastern New Jersey and along the area coasts. Elsewhere, the mixed precipitation should transition fairly rapidly to snow, which will quickly become steady and eventually very heavy. Dynamic cooling will change rain and mixed precipitation to snow gradually in all areas, slowest over portions of Southern New Jersey on Thursday morning.

Bands of heavy snow are expected to develop on Thursday morning, oriented from southwest to northeast with time, as the low pressure system rapidly strengthens offshore. Favorable dynamics in the upper levels, characterized by an impressive upper level jet streak, will support the expansion of precipitation to the west of the low pressure area.

In addition, intense mid level atmospheric dynamics are expected to come into play as the storm deepens off the coast. Impressive temperature and wind gradients, known as frontogenesis, will further enhance the lift that aids in the development of heavy precipitation. Frontogenic bands of very heavy snow are likely to set up from Southeast PA through New Jersey and into parts of NYC and Long Island, eventually shifting into Connecticut and Southern New England.

Within these bands, snowfall rates will be impressive and conditions will be extremely poor. Very heavy snowfall will create extremely reduced visibilities. Blowing and drifting of snow is also likely as the storm strengthens offshore. Roadways will quickly become snow covered and travel will be extremely hazardous — and is not recommended. Rapid snowfall accumulation is expected within these bands on Thursday morning.

It is worth restating that travel will be extremely hazardous during this time. Snowfall rates may approach 3″ per hour which is virtually unmanageable for road crews. In addition, winds will cause blowing and drifting of snow. Convectively enhanced snowfall bands create very difficult travel conditions and we do not recommend traveling tomorrow morning.

Snowfall totals are likely to be broadly dispersed. A general 8 to 12 inch range continues from yesterdays forecast throughout Central and Northern NJ, NYC, LI, Southeast NY and CT. An upgraded area of 12″+ potential has been added to some of that area — where we expect these bands to set up.

Stay tuned for further details throughout the day today.