The latest NAM data has become available.  QPF values for Philadelphia is 0.28 inches of water or about 4 inches, with cold temperatures and a high snow:water ratio greater than the usual 10:1.

This forecast is below average confidence.  This storm will involve late phasing of the northern and southern jet streams. The intensification will be occurring as it approaches and modeling often misses this scenario.  The models show a very sharp cutoff north and west.

Sometimes the best forecast is one that emphasizes that just don’t know how much snow.  It could be much more or much less.

4 inches for Philadelphia is a best guess. Less north and west, much more south and east.