Today (Wed)…

Clouds associated with the approach of a weak cold front, will increase throughout the day  today (progressing eastward) .  The southerly flow ahead of the front will advect warm air into the state allowing for temperatures to soar well above what we would normally see for the first few days of Autumn (80s).  Even though the front is weak, convection through daytime heating could produce an isolated thunderstorm along with scattered showers.  Temperatures behind the front will be slightly cooler, but overnight temperatures will not drop off much given the cloud cover.

Short Term (Thu-Sat)...

Effects from the weak cold front on Wednesday will not be noticeable on Thursday as a ridge of high pressure pushes north through Pennsylvania.  Some clouds could linger with the passage of this warm front.   The GFS predicts that Thursday will see dry conditions in the atmosphere with less clouds.  The WRF on the other hand passes a vort max through central Pennsylvania during the day on Thursday bringing mostly clouds skies and the slight chance of a shower.  I would think that a mix of clouds and sun is most likely, with subtle differences by region.   High temperatures on Thursday will remain toasty with a continued southerly flow.  Lows Thursday in the 60s.  Friday will be abnormally warm across the state with some areas, especially near Philadelphia, nearing 90.  RH will also increase ahead of the cold front expected early on Saturday.  This front will bring some showers into the state but will depend on the timing and movement of the low pressure center which will track up the St. Laurence River in Quebec.  The storm system moves out quickly bringing much cooler temperatures in its wake with a mix of clouds and sun.  Temperatures on Saturday will be 10 -15 degrees cooler than on Friday.  High pressure continues on Sunday with mostly sunny skies and seasonal temperatures.

Long Term (Next week)...

Many models see a huge cut up low developing over the Mississippi and Lower Ohio River Valleys by the start of next week. Some effects might be felt in Pennsylvania by midweek.  Temperatures will be what we would expect for this time of year.

Dan Pollak