The morning model runs continue to show that upper air temperatures are too warm for snow formation tomorrow morning in PHL and the immediate suburbs, despite the TV forecasts.

Ground temperatures, however, may be below freezing at the start of the precipitation (GFS starts somewhat earlier than the NAM ) between 6-8 AM, which may result in a brief period of sleet or freezing rain before temperatures warm up rapidly in all levels of the atmosphere. So icy conditions are a concern early.

Heavy rain is expected for much of Wednesday, although the latest NAM has backed away from the 1 inch totals.  I’ll nail down the forecast this evening, a little after 9 PM.