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.
I’ve been listening to the TV forecasts tonight and I’m hearing dire forecasts for Wednesday morning’s commute. From what I see with the latest NAM model, snow is NOT likely for Philadelphia or the immediate northwest suburbs. The upper atmosphere looks too warm for snow early Wednesday morning around here..
It’s not clear if ground temperatures will be above freezing, so some icy conditions may be possible. The NAM delays the precipitation onset until about 8 am in PHL.
We won’t know for sure until the Tuesday night model runs.
The possibility of snow for Sunday appears to have vanished— the jet stream will be less amplified due to less cold air plunging southward and low pressure develops more westward, bringing moderate to heavy rain for Sunday afternoon and evening.
But before we get to Sunday, we’ll see very cold temperatures for Saturday. Saturday will be sunny with high temperatures near 34.
Sunday will be cloudy with rain developing in the afternoon. High 44.
