THIS WEEK’S WEATHER

#Philadelphia #weather #PAwx

Rain Update

Posted Friday 08/02/24 @ 4:26 PM — Obviously, the models were about 3 hours too slow with the passage of the showers and thunderstorms. Indeed, the entire forecast from yesterday has changed; instead of the storms lingering and developing over the I-95 corridor this evening, this line of storms is now forecast to move east and away this evening.


Posted Friday 08/02/24 @ 12:57 PM — A quick update. This morning’s models have returned to forecasting some showers and thunderstorms in most areas. Most likely timing is- starting 5 PM or so in western Montgomery, Bucks and Chester counties, between 6-7 PM in Philadelphia and eastward into NJ. Heaviest rainfall is still forecast north and south of Philadelphia.


Posted Friday 08/02/24 @ 9:42 AM — What was looking like a slam-dunk drought-buster of a rainfall later today is now looking questionable. The latest HRRR shows most of the rain shearing off to our far northwest.

Just to see, I downloaded the latest hourly experimental RRFS 10z and it has heavier rain in some places, but also has large parts of the Delaware Valley with little to no rain! Here’s the latest RRFS—

10z RRFS has rain in southern and northern parts of the Delaware Valley. (Click on image for a larger view.)

To add to the uncertainty, the NAM-NEST and HRES are showing showers and storms right now, not occurring on actual radar. That undermines the rest of their forecasts. So an uncertain forecast. Some areas here will have some substantial rain, some will have little or none.

Current Water Vapor and MRMS radar at 8 AM with superimposed RAP thickness, MSL isobars and upper air windstreams. (Click on image for a larger view.)

I’ll update later.


A Pattern Change. Rain?

Posted Thursday 08/01/24 @ 4:59 PM — Just when I started to use the word “drought”, the models are forecasting a pattern change for the coming week. Additionally a tropical system is expected to form near Florida and the moisture may move up the coastline towards us next week.

We’ll see the first evidence of the pattern change late Friday and over the weekend— A deepening upper level trough will have embedded waves of low pressure bring showers and thunderstorms to our area—

GFS Upper Air forecast (700mb ~ 10,000 feet) with relative humidity. The waves (L) will induce showers and thunderstorms as they rotate up through our area Friday evening and over the weekend.

For Friday, a mix of sun and clouds will still allow high temperatures to be 95º-96º. An increasing likelihood of showers and thunderstorms, from west to east from 2 PM into the nighttime hours. Yes, the rain is actually forecast for the immediate Philadelphia area.

Show More