Philly Weekend Weather

Early cirrus clouds with approaching warm front
Cirrus clouds with approaching warm front

 

A southerly flow of warm humid air will affect our area over the weekend.  A series of frontal boundaries will move through. Exact timing of precipitation will be difficult to nail down, but most likely late Saturday afternoon into evening and similarly late Sunday into Sunday evening.

The NAM has more breaks of sun than the GFS on Saturday.

First, a warm front moves through Friday night and some light showers are possible before daybreak, then ending early morning Saturday.

On Saturday, the warm front barely clears our area.  The GFS has some sunshine breaking through in the mid morning, but has mostly cloudy by 2 PM with an increasing chance of showers in the late afternoon and evening.  High 82.  More humid.

There’s a chance of thunderstorms also Saturday evening as a weak cold front moves through.

The weak cold front is expected to remain near our area on Sunday as weak disturbances move along it, likely triggering some showers.  Sunday looks to be mostly cloudy with an increasing likelihood of showers towards evening.

 

Philly Weather Update

As mentioned yesterday, the presence of a subtropical system will affect the models and the accuracy of the forecast this weekend.

The warm coastal trough/warm front that had been expected to move through last night  has been delayed and the models show it moving through later this afternoon.  Some brightening of skies during the early afternoon. The SE surface wind flow will keep some low cloudiness and haze/fog into this late afternoon.  The winds shift to the south about 5 PM, allowing more sun later in the day.

Sunday looks to be brighter with hazy sunshine, warmer and more humid.

A complex weather pattern with a cold front and associated low in the midwest interacting with the remnants of tropical storm Ana.  The models always have trouble with these systems, affecting the forecast.

The track of the remnants of tropical storm Ana will continue to affect the accuracy of this weekend’s forecast.  Some tropical models bring the system through our area Monday into Tuesday, but the majority of the models keep it, (and much needed rain) to our east.

Philly Weekend Weather Forecast

A blocking pattern with  high pressure over the Atlantic will allow a southerly flow of warm air to be with us over the weekend.  The same blocking pattern will impede the northern movement of tropical storm Ana, although there is always uncertainty with the movement of these systems.

A weak warm front will move through Friday night and some cloudiness will linger into Saturday morning as dew points rise.  Skies should break to sunshine in the afternoon with temps getting to 80.  It will be more humid on Saturday.

The  overall dry pattern will continue for Sunday, but some moisture from tropical storm Ana may introduce some cloudiness Sunday afternoon.  Mostly sunny with some cloudiness in the afternoon. High 83 and humid.

I just want to emphasize that tropical storm Ana affects the models and introduces some increased uncertainty in this forecast.

Storm Forecasts & Other Things "up in the air".