Forecasters are underestimating the Philly snowfall for the upcoming storm.  The latest GFS data just rolled in.   The latest GFS has a QPF of 2.01 inches water, remarkably close to the NAM data.    This translates easily into 25-30 inches of snow, using the built in GFS snow algorithm.  (In fact, the built in GFS algorithm has  32-36 inches.)

I’ve been saying we would get 20-30 inches of snow for two days now,  based heavily on a consistent NAM model.   With this morning’s GFS model  output being in the same ballpark, the likelihood of getting closer to 30 inches in Philly is looking very reasonable.    And if temps stay low, it could be more than 30 inches.

(The last time I listened to KYW radio at 11:30 AM, they were still going with 12-16 inches. ).

Updates later….