As mentioned, the snow is moving in earlier than shown by yesterday’s models and it should be snowing in most areas as early as 6-7 PM. The snow will ramp up quickly.
The 1 PM (18z) runs of the NAM and GFS are available. The NAM continues with a QPF of slightly over 2 inches water equivalent. The GFS, as always, is somewhat less at 1.81 inches water equivalent. This is all for PHL airport gridpoint.
So, we’re still on track with 20-30 inches of snow with the higher end of the range more likely.
Of interest is the wind prediction, with the GFS and NAM showing sustained winds of 30-40 mph, the highest expected about daybreak Saturday.
I’ll update later. The next NAM FOUS data is usually online about 9:40 PM and some of the early GFS data hopefully available by 10:45 PM.
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. ).
