A back building storm developed along the I-80 region and caused flash flooding to occur in isolated areas.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PBZ wrote it up.
A back building storm developed along the I-80 region and caused flash flooding to occur in isolated areas.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Pittsburgh, PA wrote its last area forecast discussion before the first event at Aug 26, 7:38 PM EST, 2 hours 52 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 838 PM EDT Thu Aug 26 2021 .SYNOPSIS... Warm and humid conditions are expected through the weekend with daily afternoon shower and thunderstorm chances. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Most of the ongoing activity to the south and east of Pittsburgh was generated by an impressive outflow boundary generated by the earlier convection along the ridges. This boundary is taking advantage of the present instability (2700 CAPE on the 00Z PIT sounding) in the generation of new storms as it propagates north and west. While there is not a severe weather threat from these storms are not a their slow motion to the north and west is generating locally heavy rainfall, which could generate localized water issues. A Flood Advisory has already been issued in Wetzel County. Coverage and intensity will wane over the next few hours as instability is lost. Expect rain to mostly end by 06Z, although the far southeast may have to be watched for a stray shower overnight as an shortwave makes a slow exit across the Appalachians. Another muggy overnight period with patchy fog is anticipated, with overnight lows some 7 to 10 degrees above normal. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... After a similar start to the day on Friday, convection is expected to develop mainly east of Pittsburgh Friday afternoon and evening as vorticity advection interacts with the ridges. High pressure off the SE coast will keep temperature nearly stagnant, with oppressive humidity. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Long range deterministic models indicate that high pressure will remain near the SE CONUS/just off the coast, and if that is the case that would continue to pump heat and moisture into the Ohio Valley, while not providing enough subsidence to inhibit ascent. If this high pressure pattern were to remain as low pressure develops over the Great Lakes, thunderstorm activity is likely to continue in the long term. The wild card to this forecast would be any rapid intensification and propagation of the tropical system currently residing in the caribbean, which is unknown at this juncture. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... Low confidence forecast, due to inconsistencies in models handling of the overall pattern. General VFR forecast, with afternoon and evening convection in the east decaying during the evening hours. The VFR forecast will be interrupted by pre-dawn IFR/MVFR fog and stratus, which look to be confined to ports near river valleys. Fog will burn of Friday morning and low confidence remains on additional tsra developing during the afternoon. .Outlook... General VFR is expected through the TAF period with restrictions limited to instances of peri-dawn fog and diurnally supported moist convection. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. &&
Hazardous Weather Outlook National Weather Service Pittsburgh PA 323 AM EDT Thu Aug 26 2021 OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-029- 031-073>076-WVZ001>004-012-021-509>514-270730- Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH- Muskingum-Guernsey-Belmont-Noble-Monroe-Mercer-Venango-Forest- Lawrence-Butler-Clarion-Jefferson PA-Beaver-Allegheny-Armstrong- Indiana-Washington-Greene-Westmoreland- Higher Elevations of Westmoreland-Fayette- Higher Elevations of Fayette-Hancock-Brooke-Ohio-Marshall-Wetzel- Marion-Monongalia- Ridges of Eastern Monongalia and Northwestern Preston-Preston- Eastern Preston-Western Tucker-Eastern Tucker- 323 AM EDT Thu Aug 26 2021 This Hazardous Weather Outlook is for east central Ohio, western Pennsylvania, and northern West Virginia. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The State College radar (KCCX), 100 km away, was scanning. The volume nearest the first event began at 03:31 UTC.
1 flash flood. Local standard time, as filed.
Businesses along Route 36 affected by flooding, including Dale Smith Campers Sale.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2021Every state in 2021This day in weather historyWarnings in Pennsylvania, August 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 981673.