TheClimateChanger

GFS suggests the dry pattern persists through at least the end of the month. Will need to keep an eye out for any rogue tropical development, however. Here is the total QPF on the 12z run through 6z on 10-1:

While not the official observational site anymore, Allegheny County Airport (AGC) has received only 0.22 of an inch of rainfall so far this month. Looking through the observational records, which encompass 502 months of data [July 1, 1935 to September 15, 1952, as the official observational site; and February 1, 1999 to present with the installation of the ASOS], the driest month recorded at AGC is 0.53" in November 1939. Here are the 10 driest and wettest months observed at AGC (obviously September 2023 is not yet done). September is a month that can be very wet or very dry. It is generally a drier period of the calendar year, but occasional visits from remnant tropical cyclones can produce copious amounts of rainfall. Officially, at Pittsburgh International Airport (PIT), there has been 1.30" of rain this month, with 1.14" of that occurring on the 7th (the bulk of which fell in a single hour).

Incredible Starlink pass this evening. They were very bright in the night sky.

Nice.

Interesting. Although by 10 am, it's running right in line with all of the other local airports. I did look at some local PWS in the western Allegheny area, and they were mostly in the upper 30s to mid 40s this morning. But by 10:15 am, upper 50s and low 60s areawide. I do think it might be running a bit warm, but PIT has never done well in radiational cooling compared to much of the area. A lot of asphalt and its site on a flattened hilltop are not exactly conducive for radiational cooling. Many of the traditionally cooler sites are in valleys or at least on valley slopes with higher terrain in the vicinity.

Chilly morning, especially outside of Allegheny County with some upper 30s noted in the north. Some of the coldest lows in the region include 39 at Zelienople (PJC), Youngstown (YNG), and Franklin (FKL), 40 at New Castle (UCP), 41 at Washington (AFJ), 42 at Butler (BTP), and 43 at New Philadelphia, Ohio (PHD). The Virginia Tech mesonet site in the Canaan Valley National Wildlife Refuge (an elevated frost hollow) dropped to 30.6F.

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.

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.

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

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:

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:

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

Incredible turnaround from recent years. Again looking only at airport data, you can see the top 20 years are dominated by recent years (2018, 2019, 2022, 2017, 2021, with 2020 not far behind). Two other years from the 21st century also appear (#1, 2004; and 2009).

Just goes to show how difficult it is to have a drought in this state. Looking at airport data only for the Pittsburgh area (AGC: 1935-1952; PIT: 1953-2023), this is the 20th driest year [out of 89 years]. Only three years so far in the 21st century have been drier to date (2009, 2016 and 2002), and, of those three, just one significantly drier (2002). It is also the sixth warmest (of the past 89 years): You would think with those statistics, it would at least be "abnormally dry."

I feel like these radar estimates usually come in high, especially over long periods. Pittsburgh Airport has had 24.83" and nowhere in western Pennsylvania is shown below 25 inches. Around the airport, it shows 30-35" with an area of 25-30" just east of there over the city and river valleys. Morgantown is at 26.12", but everywhere in Monongalia County is shown in 30-35" except a small area of 25-30" well west of there and 35-40" in the ridges. It's been a fairly dry year in most of western Pennsylvania too, especially compared to recent years. No drought, but it certainly hasn't been wet.

Since August 3rd, only 7 days have been below normal at Pittsburgh, and only 2 have been more than 3 degrees cooler than normal: August 16 (-1); August 18 (-6); August 19 (-7); August 23 (-2); August 30 (-3); August 31 (-2); and September 1 (-2).

Was reading up on the Mississippi levels last year, and came across this gem from the New Orleans media published in December. The Mississippi River is low, but nowhere near its record | Environment | nola.com Do they realize the Mississippi River is a tidal reach at New Orleans? The levels are maintained by the tides. And sea levels have risen considerably since 1872. It's not at all comparing apples to apples. Here is the past several days worth of river levels at NOLA, which illustrates the tidal component. Levels dropped below 2' overnight, approaching the 1.6' from last year. These values cannot be compared to 19th century values, as sea level rises would prevent those numbers from being possible (except perhaps if drought were to be accompanied by a period of extreme northerly winds and/or a tsunami wave that would pull the water out to sea).

More climate mayhem. The mighty Mississippi is drying up for a second consecutive year. Current gage level on the Mississippi River down to -9.9 feet. This is already third lowest on record, behind 10/21/2022 (-10.81') and 7/10/1988 (-10.70'), but is forecast to continue falling to -10.6 feet by Wednesday. Next week, the river level is supposed to continue below -10 feet, so we could see the lowest flow on record at Memphis in two consecutive autumns. The long-range forecast favors drier than normal conditions across almost the entire basin in the 6-10 day and 8-14 day periods.

Impressive. The gage at Memphis is down to -9.9 feet. This appears to be the third lowest level on record beind 10/21/2022 (-10.81') and 7/10/1988 (-10.7'). It's forecast to drop to -10.6' by Wednesday, before recovering somewhat, but maintaining -9 to -10 feet, before dropping back below -10 feet early next week. The long-range forecast calls for dry weather over much of the basin, so we could make a run at lowest level on record later this month.

Big shocker there. Plan B is to block out the sun. Opinion: We're very far off course in meeting global climate goals. Get ready for Plan B (yahoo.com)nb

NOAA's NCEI has released the August 2023 and Summer 2023 rankings for the contiguous U.S. It was the 9th warmest August, and 15th warmest summer nationally. In Pennsylvania, it was a rather pedestrian 58th warmest summer on record, with a mean temperature of 68.5F, just 0.2F above the 20th century mean. In Chester County, NOAA's official ranking says that it was the 47th warmest summer on record countywide with a mean temperature of 72.5F, 1.0F above the 20th century mean.

Digging a little deeper into the contiguous U.S. data, Louisiana had its hottest summer on record. Texas and Florida both had their 2nd hottest summers on record. The hottest summer on record in Texas was 2011 and the hottest summer on record in Florida was 1998. New Mexico had its third hottest summer on record, behind only 2011 and 2020. Only 5 states were cooler than the 20th century mean (Indiana, Ohio, Kentucky, West Virginia and Tennessee).

With today's data release, NOAA's NCEI has confirmed this to be the 15th warmest summer on record nationally, with a nationwide mean temperature of 73.01F - placing slightly ahead of 1933 and just a hair behind 2007. As noted, only three summers of the 20th century were warmer (1934, 1936 & 1988). National Time Series | Climate at a Glance | National Centers for Environmental Information (NCEI) (noaa.gov)

August was the 9th warmest on record nationwide, with meteorological summer coming in 15th place. While the final ranking is not terribly impressive, it's important to note that only three summers of the 20th century were warmer than this summer nationally (1934, 1936 & 1988).

For more context, the HO-83 artificially inflated daytime maxima by up to 2C in the southwest US on sunny days with light winds (the kind of days characteristic of a place like Tuscon). 2C is huge... it's possible with current instrumentation, there may have only been 4-6 days of 110F+ in those summers. So this is incredibly impressive to be blowing away these old records like this. The HO-83 Hygro- thermometer « Climate AuditThe HO-83 Hygro- thermometer « Climate Audit Inside the HO83 Hygrothermometer « Climate Audit Note: I don't normally link to Climate Audit, but they had some excellent information on this bias in 2007/2008, with a number of links to scientific papers exploring the issue. Their angle was the recent warming was biased by this issue, but obviously time has shown this to be nonsense as it has continued to warm even with improved instrumentation. Of course, as they noted, these ASOS sites are only about 5% of the USHCN sites, so it was a negligible issue to begin with. With that said, it does give reason to be a bit skeptical of some of the extreme heat records set in that era, and there were a number of them.