The 1 AM runs of the NAM and GFS models show a significant increase in early intensification of the coastal storm for tonight into Thursday.  While the track hasn’t appreciably changed, the expansion of the snow and the western extent of the heavier precipitation has.   As a result, the NAM has changed the most with a  QPF of over 0.71 inches water.  The GFS has moved up to 0.27 QPF and the NBM (experimental National Blend) is 0.34.

This would be at least 4-5 inches for PHL, tapering rapidly as one goes westward and increasing eastward for a major snow for areas in NJ.

The 1AM model runs can be outliers, since they don’t incorporate any new radiosonde (weather balloon) data.  The extreme NAM QPF  may also be an outlier, but can’t be totally discounted.

As always, we’ll need to wait for tonight’s models for a more definitive forecast.   Stay tuned.  The early NAM data is available about 9:15  tonight.

A quick update on the status of the winter weather for Wednesday night into Thursday.

As mentioned, this storm’s track is less variable than many. What varies from model to model is the westward extent of the precipitation shield.

Tonight’s models have a wide range of QPF for the immediate Philadelphia area.  The NAM suppresses the precipitation to the east, with a very low QPF. The GFS has more extension of the snow shield westward, with a QPF of 0.30.  The experimental National Blend of Models has a QPF of 0.21.

Right now, I’m leaning towards the low levels of the NAM for PHL. That would mean about an inch of snow.   The NAM is historically good when precipitation is suppressed.

(The GFS suggests 4-5 inches.). Still too soon to be sure. Stay tuned.