As I’ve been saying for several days, the final forecast can’t be made until Wednesday night’s data comes in.  And latest NAM model data has just become available.

In conjunction with my previous post this evening regarding warm surface temperatures as an impediment to high snow accumulation, the latest NAM data suggests that much of the QPF will occur before surface temperatures in the immediate PHL area drop to freezing.

The NAM has 0.59 inches water falling before 7AM, but much of that will be rain,  snow mixed with rain,  and finally snow about 7AM.    The NAM has reduced the QPF to only 0.20 inches water after 7AM.

So I’m going to go against the TV forecasts and predict only 3-4 inches of heavy wet snow for the immediate PHL area, ending about 10 AM.

I might be wrong about this forecast, but you’re reading this blog to get the real scoop without the hype.  While everyone gets all excited about a big storm, I simply can’t ignore the warm surface temperatures with this one.

10:30 PM Update:  Latest GFS supports the forecast of only 3, maybe 4, inches of heavy snow accumulation in the immediate Philadelphia  area.  The GFS has only 0.18 inches QPF falling after 7AM.  It’s looking like most of the precipitation occurs before the cold air moves in.

I don’t think the snow will be very heavy after daybreak.