There are interesting differences in last night’s models regarding the chance of showers/thundershowers this evening. (Sunday evening)

An upper air disturbance drops down into our area this evening, between 7PM and 1 AM.  The NAM has been consistent in keeping any showers far to our north.  One version of the WRF with NAM physics (WRF-NMMB) also does the same.

The GFS  (and its similar physics version, the WRF-ARW) has showers and thundershowers making it in to the Philadelphia area towards midnight, then dissipating.   It will be interesting to see which model does the best here.

Either way, today will be hot and slightly more humid. Highs 91-93 with dew points near 60.


There isn’t much change from yesterday’s posted outlook.

Sunny skies and warm Saturday. High 88-90.

Tonight’s NAM suggests that a weak warm front moves through late Saturday afternoon.  Some cloudiness possible as a result with an increase in dew points Saturday night.

Sunday is sunny, hotter and more humid. High 90-92.

There’s a low chance of a very widely scattered brief thundershower on Saturday , late afternoon. Most areas dry.

Tonight’s WRF has a greater chance of thunderstorms Sunday evening.


With things being so quiet weather-wise, this “outlook” could easily be the final forecast for this weekend.

High pressure will be in control for the entire weekend.  Sunny skies and increasingly warm temperatures for Saturday and Sunday.  Based on the EKDMOS, high temps for Philadelphia 89-91, running about two degrees less in the suburbs to the north and west.

Some localized instability may cause very widely isolated thundershowers  Sunday late afternoon.  Most areas will be dry.  The NAM and GFS are also showing some very localized areas  of clouds for periods Sunday afternoon.  Most areas will be sunny.


Today’s official high temperature was 97 and the high heat index was 106.

The global GFS overshot the temperature forecast. The mesoscale models (NAM, WRF, HIREF) did better with the temperatures but over-forecast the pop-up showers in a big way.

Tonight’s models, just becoming available, are predicting a hotter day on Sunday than Saturday. Highs are coming in at 98-100. Thunderstorms move in from the northwest after 8PM Sunday evening.