Philly Weekend Weather Forecast

Saturday 5PM Update: The low level cloud layer didn’t clear as I had expected. We remained socked into cloudy and damp all day. Sunday still looks cloudy and damp in PHL with a chance of light scattered showers, but the real rain arrives late afternoon.

A return to colder winter temperatures will occur this week in the Thursday-Friday timeframe.  The first few days of February look to be stormy at this time (although long-range forecasts haven’t been too good this year).

The warm front that moved through on Friday, has moved north and a southwesterly flow of mild air will move in for Saturday and Sunday.

Saturday will be dry and partly to mostly cloudy, but we can’t rule out some sun breaking through during the day, especially the afternoon.  High temp 55.

Sunday will continue mild, but an approaching large storm system will bring an increasingly easterly wind and clouds and during the day  and rain by nightfall. Right now, the GFS has most of the daytime hours rain-free.  High temp 56.

Already advertised, from Sunday night through Monday, expect a stormy period with high winds.  Right now, the GFS is predicting over 3 inches of rain!

A Long Duration January Thaw

For reasons poorly understood, there is often a warmup  sometime in the interval between January 18 and January 28th most winters.  Some winters, like last year’s, the thaw was brief.

This year, we’re at the other end of the spectrum, where above average temperatures are expected from tomorrow through almost the end of January. With many days this January already running above average, calling it a “thaw” may be a misnomer.

Along with the above average temperatures will be several days of rain.

Long range models show the return of winter the last day or so January.  Snow lovers might be satisfied the first days in February.

 

 

Philly Winter Weather Update

5PM Update:  Well, it looks like the models might have blown this one(?)  And when the models get it wrong, I get it wrong.    (The GFS LAMPS is still showing sleet for a few hours this evening.  Can we believe it?)  I’ve eliminated the freezing rain references below.

As I mentioned yesterday,  “This falls into the category of a dusting or coating and at this low QPF level, this sometimes can translate into a complete zero.”

Will the TV forecasters acknowlege that the models blew the forecast or are they going to search for some area to our north and west that had some snow to validate their forecasts?

Last night’s NAM and GFS models have increased the QPF to about 0.15 inches of water falling mostly as snow.

Snow starts about 2-3 PM in PHL and continues through until 9 PM. Areas south of Philadelphia Airport will have snow mix in with sleet and possibly some freezing rain after 5 PM, reducing snow totals there.

This will be very interesting meteorologically regarding precipitation type– 

The models are predicting a wet snow, with surface temperatures just at or above freezing.  Temperatures in the upper half of the atmosphere are just marginal for snow formation, indeed in other scenarios, I would be predicting mostly sleet and freezing rain.  The models predict temperatures in the lower half of the atmosphere  to be cold enough for snow, at least north of  PHL airport.

So to me, this temperature profile appears to be an unusual one and I’m interested to see if we get mostly snow or mostly sleet or snow mixed with sleet and freezing rain. .