It’s been a long time since I was able to post a forecast early on Friday for the upcoming weekend and have confidence that things wouldn’t significantly change in a day or so.

The forecast situation for this weekend looks to be different, where high pressure builds in from the northwest and centers itself over PA, heralding in what has become an anomaly–  an extended period of dry weather!

Forecast for Saturday
GFS Forecast Saturday afternoon

Skies are expected to clear Friday afternoon and sunny skies, light winds and lower dew points should be in store for both Saturday and Sunday.  Highs on Saturday about 72 and Sunday about 74.  Enjoy!

Currently, the next chance for showers will be in over 7 days from now.


Today’s weather featured a bit more cloudiness than had been forecast and the temperatures weren’t able to reach the predicted high.  The front has stalled just a bit further north and over-running of moisture has to occurred today giving us the clouds.

As mentioned yesterday, it wouldn’t take much for the amount of rain expected on Sunday to increase, based on further intensification of the wave expected to form along the stalled front to our south. Indeed, the GFS and last night’s NAM suggested that rain might continue through the day on Sunday.

So while Friday’s model forecast had Philadelphia on the very northern fringe of precipitation on Sunday, things are now looking wetter.

This afternoon’s models are predicting a very cloudy and rainy Sunday. Rain starts in the morning and continues into the afternoon. High in the mid 60s.

Autumn, which begins tonight, continues with the rainy pattern we have had for much of this past summer.


A front will pass through Philadelphia tonight and some cloudiness may linger into early Saturday morning.

Clouds thin later in the morning Saturday and expect some sunshine and low humidity for much of the day before clouds roll in again during the late afternoon. High temperature 74.

The front that moved through earlier in the day Saturday stalls just to our south. A weak disturbance rides along the front Sunday morning.  The latest GFS has some heavy showers making their way through Philadelphia and areas south on Sunday morning.

The NAM is less impressive with the precipitation.

NAM Forecast
NAM 12 km forecast Sunday morning

Most of the models have the precipitation ending sometime early afternoon Sunday.  It will be cool with highs near 68.

This will be a close call—slightly more intensification or a difference in the position of the stalled front will greatly affect the amount of rain and whether the Eagles will be playing with drying conditions or showers.

Fri night update: Tonight’s NAM has showers before daybreak Saturday, especially northwest of the city. For Sunday, showers may linger through the afternoon.  


The flooding and devastation brought by Hurricane Florence continues in the Carolinas.

I wanted to just weigh-in on the forecasting aspect of the storm.  I haven’t heard very much credit given to the real meteorologists, mathematicians, and scientists that developed such remarkable computer models of the earth’s atmosphere.

The computer models did incredibly well with the precipitation forecast and early/late track of this storm and its remnants.   Possibly the best I’ve seen in recent years.

The new GFS-FV3 model, still in trial mode (to replace the current GFS and become operational in January 2019), also did very well.

While the intensity forecasts are generally unreliable, and were off  with this storm, (it luckily hit the coast as a category 1 instead of the previously forecast category 3-4), the rest of the forecast was very impressive.

Thank you to the National Weather Service and their scientists!