…from last night—
Earlier this week, I described this weekend’s weather as “interesting” and indeed it is a complex scenario involving a secondary coastal low pressure system and an upper atmospheric low that will interact in complex ways. See my previous discussions about the systems involved, as the general scenario appears to be playing out as predicted. Here are the latest model trends —
Freezing rain and sleet begins 5-7AM from the city just north and west, and changes to all rain from 9 AM to noon. The city proper, south and east will have mostly rain. Areas north and west will have a prolonged period of sleet and freezing rain. The graphic below is the latest NAM model forecast of PTYPE.
The other models are in general agreement.
After the changeover, rain heavy at times is expected. QPF values about 1 inch water.
Sunday night, cold air filters in in the upper atmosphere.
For Monday —An upper low trailing the surface low will bring additional precipitation on Monday. A changeover to snow and snow showers is expected during the day, however for the immediate PHL area and adjacent suburbs, surface temperatures remain above freezing until late afternoon, so accumulation will be highly limited here. Currently, the models are showing a coating to an inch by the time it ends late Monday night, with considerably more in far northwest counties.
There remains uncertainty about this Monday’s snow. Stay tuned.