A very complicated forecast is about to play out and I'm telling you right now my confidence in the forecast is considered low.  The forecast I have in place keeps most of the coast as rain and the interior experiencing a significant snow and ice storm.  However, there are several indications of the low pressure system tracking further east due to influences from latent heat release from thunderstorms along the Gulf Coast and Gulf of Mexico along with a much flatter upper level ridge ahead of the approaching disturbance.  So to say this forecast is a settled in volatility terms is leaving open a lot of surprises.

Still, given the boundary layer dynamics and the shift needed to for the storm track, I think even these considerations keep the coast as a rain threat.  My concern all day has been just inland in terms of ice and a significant ice threat at that.  For locations around White Plains, northeastern New Jersey, and the suburbs just northwest of Philadelphia, a relatively wet forecast on Thursday morning could become very icy if there is a slight shift to the east, keeping winds more east than northeast.

Another aspect that is tricky with this forecast is the intensity of the initial precipitation shield tomorrow evening where temperatures at the mid levels are below freezing and wet bulb temperatures will be below freezing for the New York City metropolitan areas and just northwest of Philadelphia.  These locations may experience a brief burst of snow and sleet leading to minor accumulations at the beginning of Rush Hour.

Below is the forecast map:

View Snow/Ice Map for December 26/27, 2012 in a larger map