A crossing shortwave trough combined with 2000 J/kg of CAPE and sufficient shear to produce a crossing line of showers and thunderstorms on July 11th. Storm strength ended up being lower than anticipated, although an isolated instance of damaging wind occurred in Westmoreland County.
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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 crossing shortwave trough combined with 2000 J/kg of CAPE and sufficient shear to produce a crossing line of showers and thunderstorms on July 11th. Storm strength ended up being lower than anticipated, although an isolated instance of damaging wind occurred in Westmoreland County.
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 Jul 11, 2:00 PM EST, 1 hour 33 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 300 PM EDT Sun Jul 11 2021 .SYNOPSIS... Showers and thunderstorms appear promising today and tomorrow as a low pressure system stalls to our west. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Increasing jet ascent, with frontogenesis in the low levels will support continued thunderstorm development this afternoon. Coincident with southerly sfc winds, northeasterly moving cells will ingest SRH. The best favored area for rotating discrete cells will be near the I-80 corridor as it interacts with a warm front situated west to east in that area. By 8pm, the potential for strong thunderstorms should reduce significantly as the atmosphere stabilizes from remnant showers/storms. However, isolated showers will likely prevail as we continue to reside in the warm sector. With regards to flooding: PWAT values will linger close to 2 inches, so moderate to heavy downpours have the potential to occur. However, with high wind shear, periods of showers and storms should continue to progress quickly across the area. Training storms in urban areas would be the only chance for localized flooding. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... Isolated thunderstorms will once again look promising tomorrow as the region reside under the warm sector. Convection will likely begin around the late afternoon/early evening after prolong sfc heating. Based on DCAPE values, wind would likely be the threat form downbursts. By Tuesday morning, a ridge to our east will amplify and the risk for storms/showers will decrease. However, hot and humid conditions will prevail. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Warm and humid conditions will prevail throughout the week under southwest flow. Thunderstorm chances will remain in the forecast as weak shortwaves periodically advance through the Ohio River Valley. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... Shower and thunderstorm chances expected this afternoon as a warm front lifts north across the region. .Outlook... Periodic restrictions with showers and storms will be possible into next week. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. &&
Hazardous Weather Outlook National Weather Service Pittsburgh PA 354 AM EDT Sun Jul 11 2021 OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-029- 031-073>076-WVZ001>004-012-021-509>514-120800- 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- 354 AM EDT Sun Jul 11 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. Isolated severe storms are possible this afternoon and evening. In addition to the severe threat, any storms will produce heavy downpours. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Isolated severe storms are possible Monday. In addition to the severe threat, any storms will produce heavy downpours. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement
National Weather Service Pittsburgh PA
127 PM EDT Sun Jul 11 2021
OHZ049-050-058-059-068-069-WVZ002>004-012-111800-
Guernsey-Monroe-Jefferson-Noble-Harrison-Belmont-Marshall-Brooke-
Ohio-Wetzel-
127 PM EDT Sun Jul 11 2021
...A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WIND AND
HEAVY RAIN WILL AFFECT EASTERN HARRISON...SOUTHERN JEFFERSON...
SOUTHEASTERN GUERNSEY...MONROE...BELMONT...EASTERN NOBLE...OHIO...
NORTHWESTERN WETZEL...MARSHALL AND BROOKE COUNTIES...
At 126 PM EDT, radar indicated strong thunderstorms were located
along a line extending from 6 miles east of Byesville to 6 miles east
of Caldwell to 9 miles north of Marietta. Movement was northeast at
40 mph.
Wind gusts up to 45 mph are possible with these storms.
Locations impacted include...
Wheeling... Moundsville...
Martins Ferry... New Martinsville...
St. Clairsville... Bellaire...
Barnesville... Cadiz...
Warwood... Bethlehem...
Woodsfield... West Liberty...
This includes the following highways...
Interstate 70 in Ohio between mile markers 188 and 225.
Interstate 70 in West Virginia between mile markers 0 and 11.
Torrential rainfall also is occurring with these storms and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
LAT...LON 3956 8081 3960 8085 3958 8089 3961 8095
3954 8104 3957 8105 3958 8126 3961 8127
3961 8128 3959 8129 3960 8139 3963 8143
3973 8143 3999 8149 4045 8090 4018 8054
3955 8064 3953 8078
TIME...MOT...LOC 1726Z 244DEG 34KT 3995 8142 3975 8138 3954 8138Special Weather Statement
National Weather Service Pittsburgh PA
331 PM EDT Sun Jul 11 2021
PAZ014-021-022-073-112000-
Armstrong-Butler-Westmoreland-Allegheny-
331 PM EDT Sun Jul 11 2021
...A STRONG THUNDERSTORM CAPABLE OF PRODUCING GUSTY WIND AND HEAVY
RAIN WILL AFFECT SOUTHEASTERN BUTLER...NORTHEASTERN ALLEGHENY...
NORTHWESTERN WESTMORELAND AND SOUTHWESTERN ARMSTRONG COUNTIES...
At 331 PM EDT, a strong thunderstorm was located near Sarver, or 11
miles south of Butler, moving northeast at 45 mph.
Wind gusts up to 45 mph are possible with this storm.
Locations impacted include...
Kittanning... Lower Burrell...
Harrison Township... Tarentum...
Natrona Heights... Brackenridge...
Ford City... Sarver...
Freeport... West Kittanning...
Saxonburg... Russellton...
Torrential rainfall also is occurring with this storm and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so monitor local radio or television
stations for additional information and possible warnings from the
National Weather Service.
LAT...LON 4058 7987 4074 7990 4095 7967 4089 7944
4070 7933
TIME...MOT...LOC 1931Z 227DEG 37KT 4071 7981
BrownThe Pittsburgh radar (KPBZ), 62 km away, was scanning. The volume nearest the first event began at 20:33 UTC.
1 thunderstorm wind. Local standard time, as filed.
Trees were reported to be blown down on to power lines in the northern part of Greensburg.
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, July 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: 972951.