A strong isolated storm created heavy downpours and tree damage to portions to Carnegie, PA June 8th. At the time of the storm, the region was still under a ridge.
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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 strong isolated storm created heavy downpours and tree damage to portions to Carnegie, PA June 8th. At the time of the storm, the region was still under a ridge. Day time heating and deep moisture created enough instability aloft to help thunderstorm development. Based off the radar, it looks like a shortwave over central Ohio, moving east towards I-70, helped make a non-severe storm become stronger. The road that received a flood report is prone to this hazard due to urban runoff.
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 Jun 8, 3:46 PM EST, 1 hour 4 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 446 PM EDT Tue Jun 8 2021 .SYNOPSIS... Warm and humid conditions will persist with afternoon and evening thunderstorms through the week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Convection to this point across the CWA has been fairly tame, as weak mid-level lapse rates are inhibiting the developing of robust updrafts, and a weak overall wind field is keeping activity unorganized. There is still a window for stronger to perhaps marginally severe convection during the late afternoon/early evening. A layer of drier mid-level air is accompanying a shortwave embedded in the flow on the back side of the Atlantic Seaboard ridge. If sufficiently strong updrafts can push an icy core into above this layer above 15,000 feet or so, a downburst wind threat could develop in isolated cases. Also, while overall flow is fairly weak, storm motions should remain sufficient to mitigate any widespread risk of flash flooding. However, high moisture content and warm rain processes point to efficient rainfall from these showers/storms, and downpours on poor drainage/urbanized areas could create isolated high water issues. Changes to grids were mostly minor overall, reflecting the ongoing scattered convective pattern. Activity should weaken during the evening with diurnal stabilization, although overnight showers will remain possible in this humid air mass. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/... The short term period forecast is a continuation of the aforementioned pattern as abundant moisture, and embedded disturbances-in-flow spawn clumps of showers and diurnally supported thunderstorms. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... By Fri, the upper-level low entrenched over the midwest today is progged to phase into the northern stream and ejects ewd. Rain chance thus will be maintained through the weekend as the Upper- Ohio Valley will be located in a broad baroclinic zone with prevailing nwly flow aloft. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... A CU/stratocu layer should develop by mid morning as low convective thresholds are met, with cig heights in the MVFR/low VFR category. Mixing should lift cigs to VFR by aftn, though diurnal instability and an approaching shortwave should spark sct showers/tstms through the evening. MVFR stratus is possible tonight with low lvl moisture in place, though confidence is not high on this occurrence. .Outlook... Periodic daily chances for showers/storms are anticipated in the warm, moist environment ovr the Upper OH Valley through much of the week, leading to brief, localized cig/vsby restrictions. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. &&
Hazardous Weather Outlook National Weather Service Pittsburgh PA 344 AM EDT Tue Jun 8 2021 OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-029- 031-073>076-WVZ001>004-012-021-509>514-090745- 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- 344 AM EDT Tue Jun 8 2021 This Hazardous Weather Outlook is for east central Ohio, northwest Pennsylvania, southwest Pennsylvania, western Pennsylvania, northern West Virginia and the northern panhandle of West Virginia. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement
National Weather Service Pittsburgh PA
547 PM EDT Tue Jun 8 2021
PAZ021-082215-
Allegheny-
547 PM EDT Tue Jun 8 2021
...A STRONG THUNDERSTORM CAPABLE OF PRODUCING GUSTY WIND AND HEAVY
RAIN WILL AFFECT CENTRAL ALLEGHENY COUNTY...
At 546 PM EDT, a strong thunderstorm was located over Green Tree, or
over Mount Lebanon, moving northeast at 25 mph.
Wind gusts up to 55 mph are possible with this storm.
Locations impacted include...
Pittsburgh... Penn Hills...
Mount Lebanon... Bethel Park...
Ross Township... Shaler Township...
West Mifflin... North Side Pittsburgh...
Baldwin... Upper St. Clair...
Scott Township... Whitehall...
This includes the following highways...
Interstate 79 in Pennsylvania between mile markers 53 and 62.
Interstate 376 in Pennsylvania between mile markers 61 and 76.
Torrential rainfall also is occurring with this storm and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
LAT...LON 4032 8011 4042 8021 4049 8009 4054 7986
4037 7992
TIME...MOT...LOC 2146Z 235DEG 23KT 4041 8007The Pittsburgh radar (KPBZ), 17 km away, was scanning. The volume nearest the first event began at 21:52 UTC.
1 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A tree fell down on an occupied car on Chestnut Street. One female received minor cuts and abrasions from broken glass.
Isolated heavy rain caused Washington Ave near Boden Ave to flood. A car was stuck in high water.
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, June 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: 960842, 960840.