Analysis valid 1:00pm EST 12 Jan 2011
The low pressure system has moved off the east coast causing heavy snowfall in the Northeast New England area. Lake effect snow is occuring throughout the Great Lakes region due to northwesterly flow, as seen in Figure 1. The 850mb map (Figure 2) supports this analysis from the warm air advection flowing through the Great Lakes causing rising motion. Figure 3 supports the sky clearing because of negative vorticity advection.
Figure 1: Surface observations and radar at 18Z.
Figure 2: 850mb map at 18Z showing warm air advection into the Great Lakes region.