January 22-24 Storm Accumulations

First, lets get caught up where we are. The NWS PHL/Mt Holly has placed the area in a Winter Storm Watch. Watches are issued 48 hours in advance of a potential threat. As the event comes closer, I expect those watches to be upgraded to warnings. I would also not be surprised if we are upgraded into a blizzard warning (3 hours of 35mph winds/gusts and falling or blowing snow reducing visibility to less than 1/4 mile). In addition, winds will be howling along the coast. Winds will be blowing in off the ocean. Couple that with normal high tides and a full moon  is a recipe for significant coastal flooding and beach erosion. This will be a very dangerous storm for coastal sections and inland.

Second, where are we going? Well, for days, the models have been showing a significant storm for a large area. This is still the case. We have a disturbance moving through the Rocky Mtns as I type and will spawn a low pressure system along the Gulf States. This low pressure system will track to the coastal waters off the NC coast. From here, there will be a upper level low pressure system which will close off and essentially "grab" the surface low pressure system off NC and keep it from moving out to sea. As a result, the surface low pressure will gradually make its way up the coast spreading precipitation from south to north. Precipitation will enter VA, NC in the morning hours and creep into DC/Baltimore during the early afternoon. Precipitation will enter our area Friday evening / night. 

From here, our surface low pressure system will intensify and as it intensifies, winds will pick up and be rather gusty, especially along the coast. Snowfall rates will also intensify and could reach 1-2"/hour in the strongest bands. Where these bands set up will really help to increase snowfall accumulations. They will not set up everywhere, but anywhere from N VA through NYC are possible. The other aspect we will have to look at is the exact track. As with most major nor'easters, there is the threat of the dreaded mix line. This will be determined by how close the low tracks along the coast and how much warm air it can inject in. In any case, for those areas that do mix, as of now, I do not think it stays a mix all that long before going back to heavy snow. In addition, as this storm does intensify, I think some areas will also have a really good shot at some thundersnow. Thundersnow and the banding is not something that can be modeled days before, that will have to be now-casted during the event. There will be a VERY sharp cutoff to the north. We have seen this type of situation before and it will be very possible to drive 30 miles and go from 2" to 12" at the northern most reach of the storm. I think as of now, that area will be far NW NJ and NE PA. In addition, it appears that maybe S New England can get in on some moderate snows, but the rest of New England may not get much. 

My very preliminary thoughts on amounts:

 Link To Townerswxpage Snow Amounts (Click)