Philly Weekend Weather Forecast

A southerly flow around high pressure will maintain mostly sunny conditions for early Saturday with a high temperature near 70, However, some middle level clouds begin moving in during the afternoon as low pressure and a frontal system  approaches from the west.  It will be cloudy by late afternoon.

This system is expected to entrain some moisture from a tropical system in the Gulf resulting in heavy rain during the afternoon and evening on Sunday.  It will windy.  High temperature near 65 on Sunday.

GFS Sunday afternoon prediction

There are differences between the NAM and GFS models regarding the timing of the heavier rain, with the NAM having the heaviest rain in the evening

Clouds break around noon

The low level cloudiness breaks at noon, and temperatures still expected to soar to near or above 80 this afternoon.

A front moves through late Sunday night with some showers.  Much cooler weather for the beginning of the week.

Postmortem:  Low level clouds never broke for sunshine; this morning’s NAM (available about 10:30 AM) apparently showed this but not the GFS.  I posted before the NAM was released.   Either way, a poor model forecast. These sort of blown forecasts makes everyone skeptical about weather forecasting.

Sunday 4PM EDT Satellite

Cloudy Saturday and Summer-like Sunday

A northeasterly flow of cool air around a high pressure system may result in some light showers Friday night, ending before daybreak on Saturday.  Low level cloudiness, similar to Friday, will also be the case  on Saturday.  Clouds may break late afternoon. High temperature 73.

Winds shift to the southwest late Saturday night, allowing unseasonably warm air to move in for Sunday.  Sunday will be sunny and summer-like with highs in the low 80s.

A cold front moves through Sunday night.

Philly Weekend Weather Forecast

High pressure over our area is gradually moving east and a return southerly flow of warm humid air will bring an increasing chance of showers by Sunday.  The remnants of tropical storm Nate will also enter the mix from late Sunday into Monday.

Saturday will be partly sunny in the morning, with increasing cloudiness in the afternoon. High 80.

For Sunday, there’s more uncertainty in the forecast—

With a tropical system in the mix, there is the inherent uncertainty about the  moisture track and timing in the picture— the NAM and GFS differ significantly with the timing of Nate’s appearance in our area. The GFS has light showers Sunday morning, then low chances of precipitation until the evening, while the NAM holds back the rain until well into Monday.

Some of the newer statistical models show a good chance of showers throughout the day Sunday and I’m going with this for now. Sunday will be cloudy, humid and warm with showers and highs near 79.