Tonight’s NAM model data has become available.  Here are the trends– the NAM has reverted back to its forecast from a day ago. The storm is a bit less developed and a bit faster.  Total QPF values about 0.70 inches water with the heaviest snow ending about 8-9 AM Thursday.

Based on temperature profiles, the precipitation starts as rain or rain mixed with snow about midnight Wednesday and changes to snow sometime between 3-4 AM, then continues as snow until 8-9 AM.  Warm surface temperature before the storm will reduce snowfall accumulations. Best guess is about 4 inches in the immediate PHL area, up to 6-8 inches north and west, less in southern NJ.

This afternoon’s GFS had much higher QPF values and greater intensification of the storm. ( Tonight’s GFS model data won’t be available until later tonight.)

Will update tomorrow morning, but we won’t really have a handle on this storm until Wednesday evening’s model runs.

A quick 11 pm  update- the latest GFS is similar to the NAM – QPF similar (0.89)  and ending earlier  about 7-8 AM

A quick update.  Latest NAM shows a significant snowfall for the PHL area, starting after midnight Wednesday and continuing into the morning on Thursday.  Temperatures for the storm have continued to drop, the low pressure system in more intensified and slower. Current QPF values are over 0.60 inches water which translates into over 6 inches of snow.

This situation continues to change.  Stay tuned.