A quick update- both the NAM and GFS show the light snow starting earlier than previously expected.  Light snow now starts in the evening tonight (Thursday)  rather than around midnight.

The usual spread in QPF values is being shown- (the NAM often  shows larger amounts than the GFS in these scenarios)- the NAM QPF is 0.23 and the GFS is 0.11 inches water for PHL.     An average of the two QPF’s is often a good guess, or about 2 inches of snow in PHL, more to the south and east.

My next update about 9:45 PM tonight with this evening’s NAM FOUS data.

One more thing– another low pressure system on Saturday, still expected to miss us and pass to our east, is showing different timing and and a track closer to the coast.  This still needs to be watched. 

A quick update on the light snow predicted by the NAM and GFS for the period late Thursday night through daybreak Friday.

The trend has been a gradual creep upward in the QPF values.

Tonight’s NAM shows a QPF of 0.25 inches water, which translates into the possibility of 2-3 inches of snow for the immediate PHL area by daybreak Friday.

The latest GFS has a lower QPF of 0.10  water, about 1 inch of snow.

Would continue to expect some further changes in the forecast.