E PA/NJ/DE Summer 2026 Obs/Discussion

[BBasile]

The weather is currently beautiful.  69F and winds gusting into the 20's.   The sky is glowing orange.  Making me long for the days of autumn right now.   

[MGorse]

0.65 inches of rain. Had a decent period of wind gusts to around 40 mph at the end of the convection, essentially in the wake of it. Quite the wind shift with that as well and a temperature/dew point drop.

[Kevin Reilly]

18 minutes ago, MGorse said:

0.65 inches of rain. Had a decent period of wind gusts to around 40 mph at the end of the convection, essentially in the wake of it. Quite the wind shift with that as well and a temperature/dew point drop.

I’m pretty sure the actual low pressure probably like 1010 mb passed right overhead here in central Delaware County looking at the cloud and wind vectors visually.  

[MGorse]

16 minutes ago, Kevin Reilly said:

I’m pretty sure the actual low pressure probably like 1010 mb passed right overhead here in central Delaware County looking at the cloud and wind vectors visually.  

Yeah that is about where much of the guidance had it, plus it was probably convectively enhanced some.

[mattinpa]

Collegeville had a severe thunderstorm warning and flood warning - by far the main thing seen was very heavy rain. 

[Psychguy]

Have not seen rain that torrential in a long time… and the winds were impressive after the heaviest rain passed. Nice and cool out now this evening… wondering if the worst of the humidity/heat is now passed on for the remainder of the summer?!?! Nothing real hot seems to be popping up in any extended forecasts!

[KamuSnow]

2 hours ago, BBasile said:

The weather is currently beautiful.  69F and winds gusting into the 20's.   The sky is glowing orange.  Making me long for the days of autumn right now.   

Those winds afterwards reminded me of that exactly, like a nice cold frontal passage with temps dropping and gusty winds.

[LVLion77]

The weather is currently beautiful.  69F and winds gusting into the 20's.   The sky is glowing orange.  Making me long for the days of autumn right now.   

Best time of the year! I love Sept and Oct… warm days, cool nights. An occasional tropical storm is nice too with nor’easters to follow.

[The Iceman]

2.1” today. Had multiple trees down in the area blocking roadways probably from the waterlogged soil and the gusty winds as the storms moved out. 

[ChescoWx]

Widespread cool 50's overnight with our usual chilly spot in Warwick Township down to 54.4. In most spots it was our chilliest morning since back on July 26th. Below normal temperatures look likely to continue through most of this week with highs mainly in the 70's and lows in the upper 50's to lower 60's. Some shower chances but no washouts around this weekend before we clear out to start the new work week.

[Birds~69]

Hopefully something destructive happens shortly weather-wise... that's all I'm saying.

Sports brain thinks, Phils creeping in on the Braves, Birds start shortly, LeBron stretching as much as a 41-year-old male can.... Fly-guys jump out early. Good times ahead!!

[Hurricane Agnes]

I ended up with 0.99" from yesterday's rain (and ended up driving through it after I was done helping my niece get moved into her apartment on Temple's campus). I'm now up to 6.47" total of rain for August.

My low was a refreshing 61 (coolest since an unusual 59 back on July 24). High got up to 82.

Currently 74 with dp 65.

 

[Eskimo Joe]

@MGorsegreat job by Mt. Holly on the rapid damage assessment. Tornado Watch verified.

[ChescoWx]

A bit more humid today before a cold front crosses the area late tonight which could spark some showers but will then usher in some beautiful weather through at least mid-week with below normal highs in the mid to upper 70's and lows in the 50's.

[Birds~69]

Overcast 73F/DP 70F

Critters are doing late season critter things...

[ChescoWx]

Some of you may remember I used a program called WXSIM to build my own "in my backyard" forecast. Well with AI  and my own detailed weather station climate history at this location since 2004. I have developed a new hyper local backyard forecast. Below is the high level background on how it was built. I will also track this AI forecast vs. my NWS Point and Click forecast to see how accurate or not it actually turns out to be.

How the East Nantmeal Backyard Forecast Is Built

A ten-day forecast for one hilltop in northern Chester County, trained on that hilltop’s own twenty-two year record — and measured against the National Weather Service’s own guidance on days it had never seen. 40.10968°N, 75.73363°W · 677.7 ft USGS 3DEP

Davis Vantage Pro 2, fan-aspirated, in service since 2004

CoCoRaHS · NWS Skywarn CHPA-174

The short version

Five weather models are pulled for this exact coordinate — the European ECMWF, NOAA’s GFS, the German DWD ICON, the Canadian GEM, and the National Weather Service’s own National Blend of Models. Each one is corrected using its own track record at this East Nantmeal site — how wrong it has been here, in this month, at this hour of the day, at this many days out. The corrected forecasts are then combined, weighted by how much each has earned. Finally the whole trace is nudged toward what the station is reading right now, by an amount that decays as the present stops mattering.

Nothing in it is a physical simulation. It does not model soil moisture or cold-air drainage from first principles. It measures what those things have actually done to this thermometer, over years, and applies that.

The site

Everything rests on one sensor. A Davis Vantage Pro 2 with a solar fan-aspirated shield, five feet above ground over grass, in service since 2004. The anemometer is roof-mounted, and reads well below open exposure because hills rise in every direction.

Corroboration: the station behaves like its elevation and is accurate

A forecast trained on one sensor invites an obvious question — is that sensor telling a coherent story, or just producing numbers? One way to test it is to compare against a research-grade station nearby and ask whether the difference between them looks like physics.

Avondale 2N is a U.S. Climate Reference Network site about nineteen miles south, at 409 ft — 268 ft below East Nantmeal. USCRN stations use triple-redundant sensors and are built for exactly this kind of reference use. The two records overlap for 7,139 days, from January 2007 to August 2026.

East Nantmeal minus Avondale 2N, 7,139 overlapping days, 268.5 ft apart.

The two stations track each other almost perfectly day to day — r = 0.996 on highs and 0.988 on lows across nearly twenty years. And the offset between them is exactly the shape elevation predicts: the higher site runs cooler by day and warmer by night, giving East Nantmeal the narrower diurnal range. Cool days come from elevation; mild nights come from cold air draining off a hilltop into the valleys instead of pooling on it.

Expressed as a lapse rate, that is −5.08 °F per 1,000 ft on highs and +5.23 on lows. Earlier work in this archive, using an entirely different station pair — Phoenixville 1E, some 550 ft lower — and a different era, arrived at −5.23 and +4.85. Two independent comparisons landing within a few tenths of each other! 

 

I will post the latest forecast below. Let me know if any questions or suggestions. Thanks!

[ChescoWx]

[JTA66]

49 minutes ago, ChescoWx said:

Some of you may remember I used a program called WXSIM to build my own "in my backyard" forecast. Well with AI  and my own detailed weather station climate history at this location since 2004. I have developed a new hyper local backyard forecast. Below is the high level background on how it was built. I will also track this AI forecast vs. my NWS Point and Click forecast to see how accurate or not it actually turns out to be.

How the East Nantmeal Backyard Forecast Is Built

A ten-day forecast for one hilltop in northern Chester County, trained on that hilltop’s own twenty-two year record — and measured against the National Weather Service’s own guidance on days it had never seen. 40.10968°N, 75.73363°W · 677.7 ft USGS 3DEP

Davis Vantage Pro 2, fan-aspirated, in service since 2004

CoCoRaHS · NWS Skywarn CHPA-174

The short version

Five weather models are pulled for this exact coordinate — the European ECMWF, NOAA’s GFS, the German DWD ICON, the Canadian GEM, and the National Weather Service’s own National Blend of Models. Each one is corrected using its own track record at this East Nantmeal site — how wrong it has been here, in this month, at this hour of the day, at this many days out. The corrected forecasts are then combined, weighted by how much each has earned. Finally the whole trace is nudged toward what the station is reading right now, by an amount that decays as the present stops mattering.

Nothing in it is a physical simulation. It does not model soil moisture or cold-air drainage from first principles. It measures what those things have actually done to this thermometer, over years, and applies that.

The site

Everything rests on one sensor. A Davis Vantage Pro 2 with a solar fan-aspirated shield, five feet above ground over grass, in service since 2004. The anemometer is roof-mounted, and reads well below open exposure because hills rise in every direction.

Corroboration: the station behaves like its elevation and is accurate

A forecast trained on one sensor invites an obvious question — is that sensor telling a coherent story, or just producing numbers? One way to test it is to compare against a research-grade station nearby and ask whether the difference between them looks like physics.

Avondale 2N is a U.S. Climate Reference Network site about nineteen miles south, at 409 ft — 268 ft below East Nantmeal. USCRN stations use triple-redundant sensors and are built for exactly this kind of reference use. The two records overlap for 7,139 days, from January 2007 to August 2026.

East Nantmeal minus Avondale 2N, 7,139 overlapping days, 268.5 ft apart.

The two stations track each other almost perfectly day to day — r = 0.996 on highs and 0.988 on lows across nearly twenty years. And the offset between them is exactly the shape elevation predicts: the higher site runs cooler by day and warmer by night, giving East Nantmeal the narrower diurnal range. Cool days come from elevation; mild nights come from cold air draining off a hilltop into the valleys instead of pooling on it.

Expressed as a lapse rate, that is −5.08 °F per 1,000 ft on highs and +5.23 on lows. Earlier work in this archive, using an entirely different station pair — Phoenixville 1E, some 550 ft lower — and a different era, arrived at −5.23 and +4.85. Two independent comparisons landing within a few tenths of each other! 

 

I will post the latest forecast below. Let me know if any questions or suggestions. Thanks!

Are you saying we may finally be able to answer the age-old question, “How much for Philly?” 

78F/DP 66F

Went to mow an area of the yard I only get to once a month or so. Wasn’t sure I’d be able to get to it, expecting muddy conditions. But despite all the rain this past week, the soil was just damp, no mud.

[ChescoWx]

5 minutes ago, JTA66 said:

Are you saying we may finally be able to answer the age-old question, “How much for Philly?” 

78F/DP 66F

Went to mow an area of the yard I only get to once a month or so. Wasn’t sure I’d be able to get to it, expecting muddy conditions. But despite all the rain this past week, the soil was just damp, no mud.

If not for Philly maybe the how much for my backyard question LOL!