Heavy Snow from the Midwest into the Great Lakes; Locally Heavy Rain in the Western Gulf Coast

A significant winter storm will produce a broad area of moderate to heavy snow from the Midwest through the western Great Lakes. Significant snow accumulations of 6-12 inches, and locally more than 1 foot, and gusty wind may cause hazardous travel conditions. Thunderstorms, some severe, and showers may produce locally heavy rain and isolated flash flooding along the western Gulf Coast. Read More >

February 4, 2006
Winter Weather Event Review
Section 6: Summary

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Section 1 -- Section 2 -- Section 3 -- Section 4 -- Section 5 -- Section 6

This was a very difficult warn verses no warn event. The forecasters were challenged with mixed signals leading up to the event. On the one hand the model trends showed an overall westward and warmer trend but also tended to linger precipitation longer when it was cold enough for snow. Also, HPC solutions trended back and forth and trended above warning criteria when Wilmington had to make the warn/no warn decision.

Some preliminary findings:

Although the model soundings and QPF showed the potential for warning criteria snowfall and lagged precipitation longer in the cold air the model signals (upper divergence, isentropic lift, favorable forcing) indicated that the accumulating snow would end quicker than the QPF indicated.
Conceptual models regarding path of the synoptic features and trends proved to be helpful in this case.
Boundary layer temperatures and precipitation type was crucial to the changeover and height of the freezing level was superior to thickness techniques.
The warm ground at the start of the event played a role in keeping snow accumulations down.
A surface low track along the spine of the Appalachian as initially indicated by the NAM solution is not a climatologically favored track.