Pittsburgh/Western PA Fall 2023 Discussion

[Ahoff]

Since it's September, even though it'll be feeling like July for a few days, I'll open this thread.

[KPITSnow]

AccuWeather says 97 on Wednesday. I’d rather just die. 

[TheClimateChanger]

The dreaded 89 today, but 90 looks like a good bet tomorrow through Wednesday. Dulles Airport, near Washington, D.C. reached 99F today.

[Ahoff]

I’m in Austin this weekend, it’s been 102 each day.  Pretty brutal when you’re at a Longhorn’s game.

[meatwad]

90 at Pit

[TheClimateChanger]

2 hours ago, meatwad said:

90 at Pit

Yup, reached 91, which matches July 28th for the highest of the year. Only the third 90+ of the year, although the current forecast has 91 for tomorrow & 90 on Wednesday for the airport. After that, it looks like we may be done for 90s until next year, although you can’t rule out an isolated 90+ even into late September.

[TimB]

Fourth year out of the last 7 when the warmest temp of the season occurred in September (including ties). Two of the other three had their max in June. So only one out of the last 7 years (2020) had a max that occurred solely in July or August.

[Ahoff]

#Summergettingcooler, lol.

[ChalkHillSnowNut]

Good riddance to this crap tomorrow night!

[TimB]

Another 90. First heat wave by definition since 2020.

Also the 4th heat wave at least partially in September since 2010. Prior to that we hadn’t had one in September since 1973.

[ChalkHillSnowNut]

Done for the season let’s hope-no more 90’s! 

[Ahoff]

Fall looks to make its entrance next week.

[Ahoff]

What's up with the sensor's at the airports?  KPIT seems to be running 2-4 degrees warmer than Allegheny County for weeks now?

[Ahoff]

Today is the first measurable rain since August 25th.

[TimB]

2 hours ago, Ahoff said:

Today is the first measurable rain since August 25th.

PIT is over an inch. About 3/4” of which fell in 8 minutes.

[KPITSnow]

Got absolutely blasted in the north hills. 

[TheClimateChanger]

Very hit or miss. Nothing in my neighborhood this evening.

[ChalkHillSnowNut]

We got 2 decent downpours with thunder and lightening-like 11AM and then again around 6pm

[TimB]

This morning’s low of 60 is our 9th low of 60+ this month, making this the 9th consecutive September with at least 9 lows of 60+. Prior to this stretch, we’d never done that more than 5 years in a row at the airport, and never at any observing site in the period of record outside of an extremely suspect stretch from 1889-1913 where every September had double digit days with lows of 60+.

[TheClimateChanger]

Chamber of commerce weather in Pittsburgh. Here is the point-click forecast centered on the official observation site at Pittsburgh International Airport:

[TimB]

PIT has to be running high. 67 at PIT, 64 at AGC right now.

[TheClimateChanger]

32 minutes ago, TimB said:

PIT has to be running high. 67 at PIT, 64 at AGC right now.

Maybe slightly, but these single point in time comparisons are not particularly helpful in making that determination. Just like the claim that: "KPIT seems to be running 2-4 degrees warmer than Allegheny County for weeks now?"

In fact, this month, the mean difference between the two sites this month has only been 0.1F:

[TheClimateChanger]

Looking at all Septembers from 1999-2022, AGC has averaged 0.5F warmer than PIT, so it's a little unusual for PIT to be warmer by 0.1F, but certainly not unprecedented. PIT was also warmer than AGC in 2004, 2009, 2013, 2017 and 2018 in the month of September. Definitely not running 2-4 degrees too warm. If anything, it was unusual AGC was running 1-1.5F warmer for awhile, so I suspect PIT's sensor was actually running 0.5-1F too low for a while, so even a slight warm bias feels exaggerated.

PIT:

AGC:

 

[TheClimateChanger]

How about daily average maximum temperatures? PIT is running 0.3F warmer than AGC this month. That's not surprising at all: PIT has averaged 0.1F warmer than AGC for daily average maximum temperature in the month of September for 1999-2022, so that's only a 0.2F difference from the long-term mean difference.

PIT: 75.6F mean daily maximum temperature

AGC: 75.5F mean daily maximum temperature

[TheClimateChanger]

Just looking over those maximum temperatures, and you can see there was a much more significant warming at PIT relative to AGC in the 2017-18 timeframe, and, on the flipside, it was highly unusual for AGC to have a September average maximum of 1.0F warmer than PIT last year.

[TimB]

1 minute ago, TheClimateChanger said:

Just looking over those maximum temperatures, and you can see there was a much more significant warming at PIT relative to AGC in the 2017-18 timeframe, and, on the flipside, it was highly unusual for AGC to have a September average maximum of 1.0F warmer than PIT last year.

2018 was the year there was an obvious sensor issue at PIT for the first 10 days of the month, so it’s tough to make any comparisons using that month. Not only was PIT 3-4 degrees warmer during the heat wave early that month, it was also 3-4 degrees warmer for the duration of the remnants of Gordon when there was no insolation, etc. to produce any variation.

[TimB]

That said, solid analysis and the rest of it probably is normal variation and not a sign of an obvious issue. Besides, why are we quibbling about a degree or two when the NWS allows the 77.3 monthly mean from September 1881 to stand as a legitimate record?

[TheClimateChanger]

1 hour ago, TimB said:

That said, solid analysis and the rest of it probably is normal variation and not a sign of an obvious issue. Besides, why are we quibbling about a degree or two when the NWS allows the 77.3 monthly mean from September 1881 to stand as a legitimate record?

Lol, no doubt. September 1881 is probably the legit warmest September in history, but that value is probably 3-5 degrees too high. I doubt that record will ever be broken.

And I did want to point out, there's a weird trend/pattern where PIT runs 2-4 degrees warmer than AGC in the late morning, but by early to mid-afternoon the two sites are equal or AGC is actually a tad warmer.

In any event, it looks like the sensor may be running a bit high at the moment - but probably no more than about a half degree. But it probably seems worse because I suspect the previous sensor was running 0.5-1F too cool for awhile.

I did notice it was running warmer until the 1"+ rainfall earlier this month, so I suspect some of the difference was legitimate. PIT was one of the drier locations in SW PA in August (nearly an inch below normal, when many spots were well above normal), and plus there's a lot of construction/turned over soil around the airport grounds, so the locally drier soils were probably helping to push the temperatures up there. Since the rains earlier this month, it's actually been running a bit cooler than AGC.

Incidentally, AGC largely escaped the storms earlier this month, and has only picked up 0.15" for the entire month to date - with little if anything on the immediate horizon.

[TimB]

No idea why the NWS decided to undercut guidance and forecast a low of 44 this morning, that busted badly and PIT didn’t get below 50.

[Ahoff]

PIT at 50 and AGC at 48 this morning...hmmm.

 

Is there anywhere to get AGC historic data like we can for PIT?  I don't know where to look.