A series of weak shortwaves in the mid-level flow lended support to thunderstorm development on August 20th. Daytime heating was slowed by a cirrus shield earlier in the day, but later strong heating, continued moisture advection, and up to 30 knots of mid-level flow provided support for strong to severe thunderstorms.
Every event with a place to put it. Tap one for its entry below.
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 series of weak shortwaves in the mid-level flow lended support to thunderstorm development on August 20th. Daytime heating was slowed by a cirrus shield earlier in the day, but later strong heating, continued moisture advection, and up to 30 knots of mid-level flow provided support for strong to severe thunderstorms. Shear was weak overall, but the presence of ample downdraft CAPE supported a threat of wind damage from downbursts.
Storms forming in the mid to late afternoon hours, although becoming strong, did not produce any severe weather reports. It was not until after 7 PM that storms were able to become strong enough to produce many reports of tree damage, with all of the WEst Virginia reports coming from a storm that crossed Marion 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 Aug 20, 9:06 PM EST, 24 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 1006 PM EDT Tue Aug 20 2019 .SYNOPSIS... Warmth, humidity, and daily thunderstorm chances will continue through mid-week. Less-humid air and seasonable temperature can be expected for the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Leading convection across eastern Ohio and entering western PA should continue over the next couple hours but decrease intensity with decreasing instability...lessening the severe threat. Activity should fill in back to the west with increasing upper support...shifting concern overnight to more of a relatively isolated flood threat for basins in eastern Ohio zones where a handful of basins are close to FFG values from earlier storms. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Instability will remain on Wed, but lapse rates are expected to weaken (either from being worked over by Tue storms or from advection of warmer air aloft). So, although thunderstorms can be expected ahead of a swd-advancing cold front, potential for strong updrafts is diminished by Wed afternoon. A cold front will advance toward the region on Thu, and greatest rain chances shift swd with the boundary. There is uncertainty as to where the boundary ultimately stalls, but it appears that its resting place may be along the Mason-Dixon line, providing a focus for showers and storms on Thu/Thu night in association with a strong shortwave trough prior to the front's swd departure. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As high pressure builds in behind the front amid a broad upper-level trough in the ern CONUS, and dry air erodes any low-level moisture, a seasonal end to the week is anticipated, with little humidity and minimal rain chances. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... VFR largely expected for most of the night with brief MVFR possible associated with any showers/storms that impact any TAF locations. MVFR/IFR restrictions may develop by early morning with increased moisture from overnight convection. .Outlook... Periodic restrictions are likely through Friday morning as a series of disturbances cross the region. VFR/dry weather conditions will return this weekend. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. &&
Hazardous Weather Outlook...UPDATED National Weather Service Pittsburgh PA 1030 AM EDT Tue Aug 20 2019 MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023- 029-031-073>076-WVZ001>004-012-021-509>514-211430- Garrett-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-Westmoreland Ridges- Fayette-Fayette Ridges-Hancock-Brooke-Ohio-Marshall-Wetzel-Marion- Monongalia-Ridges of Eastern Monongalia and Northwestern Preston- Preston-Eastern Preston-Western Tucker-Eastern Tucker- 1030 AM EDT Tue Aug 20 2019 This Hazardous Weather Outlook is for western Maryland, east central Ohio, northwest Pennsylvania, southwest Pennsylvania, west central Pennsylvania, western Pennsylvania, northern West Virginia and northern panhandle of West Virginia. .DAY ONE...Today and tonight. Severe thunderstorms are possible this afternoon and evening, and will be capable of producing damaging wind gusts and possibly hail. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures. Kramar
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
948 PM EDT TUE AUG 20 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0940 PM TSTM WND DMG ST. CLAIRSVILLE 40.08N 80.90W
08/20/2019 BELMONT OH LAW ENFORCEMENT
TREE DOWN ALONG ROUTE 40.
&&
EVENT NUMBER PBZ1902907
SKHSpecial Weather Statement National Weather Service Pittsburgh PA 958 PM EDT Tue Aug 20 2019 OHZ041-PAZ020-021-029-WVZ001-002-210245- Columbiana-Beaver-Washington-Allegheny-Brooke-Hancock- 958 PM EDT Tue Aug 20 2019 ...AN AREA OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT SOUTHEASTERN COLUMBIANA...NORTHWESTERN WASHINGTON... SOUTHERN BEAVER...NORTHWESTERN ALLEGHENY...NORTHEASTERN BROOKE AND EASTERN HANCOCK COUNTIES... At 958 PM EDT, strong thunderstorms were clustered over New Cumberland, or near Weirton, moving east at 35 mph. Wind gusts up to 45 mph are possible with this storm. Locations impacted include... Moon Township... Weirton... East Liverpool... Aliquippa... Monaca... Robinson Township... Cecil-Bishop... Economy... Ambridge... Coraopolis... Calcutta... Baden... This includes Interstate 376 in Pennsylvania between mile markers 39 and 60. Campers should consider seeking sturdy shelter until this storm passes. LAT...LON 4034 8058 4068 8058 4068 8015 4032 8017 TIME...MOT...LOC 0158Z 257DEG 28KT 4050 8057
Special Weather Statement
National Weather Service Pittsburgh PA
1000 PM EDT Tue Aug 20 2019
PAZ007-008-013>015-020>022-210245-
Armstrong-Butler-Clarion-Venango-Lawrence-Mercer-Beaver-Allegheny-
1000 PM EDT Tue Aug 20 2019
...A STRONG THUNDERSTORM CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT
EASTERN MERCER...NORTHEASTERN BEAVER...SOUTHWESTERN VENANGO...EASTERN
LAWRENCE...BUTLER...NORTHEASTERN ALLEGHENY...NORTHWESTERN ARMSTRONG
AND WEST CENTRAL CLARION COUNTIES...
At 1000 PM EDT, a strong thunderstorm was located near Zelienople, or
12 miles west of Butler, moving east at 30 mph.
Wind gusts up to 45 mph are possible with this storm.
Locations impacted include...
Cranberry... Butler...
Oil City... Beaver Falls...
Grove City... Franklin...
Monaca... Harrison Township...
Economy... Ellwood City...
Homeacre-Lyndora... New Brighton...
This includes the following highways...
Pennsylvania Turnpike between mile markers 10 and 33.
Interstate 79 in Pennsylvania between mile markers 77 and 132.
Interstate 80 in Pennsylvania between mile markers 14 and 47.
Interstate 376 in Pennsylvania between mile markers 31 and 39.
LAT...LON 4067 8043 4101 8031 4141 8021 4142 7961
4063 7971
TIME...MOT...LOC 0200Z 257DEG 28KT 4089 8013Special Weather Statement
National Weather Service Pittsburgh PA
1006 PM EDT Tue Aug 20 2019
OHZ059-PAZ029-031-WVZ003-004-012-021-509-510-210245-
Belmont-Greene-Washington-Marshall-Ridges of Eastern Monongalia and
Northwestern Preston-Ohio-Marion-Monongalia-Wetzel-
1006 PM EDT Tue Aug 20 2019
...A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WIND
WILL AFFECT SOUTHEASTERN BELMONT...SOUTHWESTERN WASHINGTON...
GREENE...MONONGALIA...SOUTHEASTERN OHIO...NORTHEASTERN WETZEL...WEST
CENTRAL PRESTON...MARSHALL AND MARION COUNTIES...
At 1006 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Powhatan Point to Enterprise.
Movement was northeast at 30 mph.
Wind gusts up to 45 mph are possible with these storms.
Locations impacted include...
Morgantown... Fairmont...
Moundsville... Waynesburg...
Westover... Mannington...
Star City... Triadelphia...
Valley Grove... Pleasant Valley...
Winfield... Powhatan Point...
This includes the following highways...
Interstate 68 in West Virginia between mile markers 1 and 5.
Interstate 70 in West Virginia between mile markers 7 and 14.
Interstate 70 in Pennsylvania between mile markers 0 and 6.
Interstate 79 in Pennsylvania between mile markers 0 and 5.
Interstate 79 in West Virginia between mile markers 130 and 160.
LAT...LON 3944 8028 3943 8029 3944 8033 3945 8038
3989 8084 4017 8048 3955 7982 3939 8018
TIME...MOT...LOC 0206Z 230DEG 24KT 3984 8073 3944 8030Special Weather Statement National Weather Service Pittsburgh PA 1010 PM EDT Tue Aug 20 2019 OHZ050-PAZ021-029-031-WVZ002>004-210245- Jefferson-Greene-Washington-Allegheny-Marshall-Brooke-Ohio- 1010 PM EDT Tue Aug 20 2019 ...A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT SOUTHEASTERN JEFFERSON...WESTERN WASHINGTON...WEST CENTRAL ALLEGHENY...NORTH CENTRAL GREENE...OHIO...NORTHEASTERN MARSHALL AND BROOKE COUNTIES... At 1010 PM EDT, radar indicated strong thunderstorms were located along a line extending from Mingo Junction to Triadelphia. Movement was northeast at 30 mph. Wind gusts up to 45 mph are possible with these storms. Locations impacted include... Wheeling... Weirton... Steubenville... Washington... Warwood... Wellsburg... Bethlehem... West Liberty... Triadelphia... Avella... Clearview... Valley Grove... This includes the following highways... Interstate 70 in West Virginia between mile markers 2 and 14. Interstate 70 in Pennsylvania between mile markers 0 and 19. Interstate 79 in Pennsylvania between mile markers 37 and 41. LAT...LON 4042 8018 4001 8025 4000 8071 4037 8069 TIME...MOT...LOC 0210Z 246DEG 25KT 4034 8062 4004 8065
Special Weather Statement National Weather Service Pittsburgh PA 1025 PM EDT Tue Aug 20 2019 PAZ020>022-029-073-075-210300- Armstrong-Westmoreland-Beaver-Washington-Allegheny-Fayette- 1025 PM EDT Tue Aug 20 2019 ...A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT CENTRAL WASHINGTON...SOUTHEASTERN BEAVER...ALLEGHENY... WESTERN WESTMORELAND...SOUTHWESTERN ARMSTRONG AND NORTHWESTERN FAYETTE COUNTIES... At 1025 PM EDT, radar indicated strong thunderstorms were located along a line extending from Wexford to 6 miles south of Washington. Movement was east at 40 mph. Wind gusts up to 45 mph are possible with these storms. Locations impacted include... Pittsburgh... Penn Hills... Mount Lebanon... Bethel Park... Ross Township... McCandless Township... Monroeville... Moon Township... McMurray... McKeesport... Washington... Franklin Park... This includes the following highways... Interstate 70 in Pennsylvania between mile markers 14 and 50. Pennsylvania Turnpike between mile markers 31 and 67. Interstate 79 in Pennsylvania between mile markers 25 and 77. Interstate 376 in Pennsylvania between mile markers 57 and 84. LAT...LON 3994 7979 4007 8032 4066 8016 4066 7956 TIME...MOT...LOC 0225Z 260DEG 34KT 4064 8008 4009 8025
The Pittsburgh radar (KPBZ), 112 km away, was scanning. The volume nearest the first event began at 02:30 UTC.
3 thunderstorm wind. Local standard time, as filed.
County 911 officials reported a number of trees down across Marion County.
A county 911 official reported multiple trees down in Carolina.
County 911 officials reported multiple trees down in Fairmont.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in West Virginia in 2019Every state in 2019This day in weather historyWarnings in West Virginia, August 2019
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: 853490, 853491, 853492.