A shortwave trough over the Great Lakes interacting with a quasi-stationary boundary over eastern Ohio and western PA spawned severe weather from mid afternoon through late evening. MLCAPE near 2000 J/kg along with a relatively strong, elongated shear profiles led to an environment for strong to severe winds and possible tornadoes.
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 shortwave trough over the Great Lakes interacting with a quasi-stationary boundary over eastern Ohio and western PA spawned severe weather from mid afternoon through late evening. MLCAPE near 2000 J/kg along with a relatively strong, elongated shear profiles led to an environment for strong to severe winds and possible tornadoes.
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 6, 1:48 PM EST, 2 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 248 PM EDT Tue Aug 6 2024 .SYNOPSIS... Showers and thunderstorms are expected into this evening as low pressure crosses the region. Some storms could be severe with damaging wind, large hail, and isolated tornadoes. Isolated instances of flash flooding are also possible from training storms. Shower chances will continue into Wednesday as the low exits. Periodic shower chances continue east of Pittsburgh until a cold front brings chances for area wide showers and thunderstorms Friday. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Showers and thunderstorms likely mainly this afternoon and evening - Severe storms possible with damaging wind, large hail, and isolated tornadoes _______________________________________________________________ Severe thunderstorms are ongoing north of Pittsburgh, generally near a quasi-stationary boundary. Instability increased rapidly by the midday hours, with 1500-2000 J/kg of MLCAPE noted north of I-70 on mesoanalysis plots. The 18Z PBZ sounding was on the higher end of this range, and included almost 3700 J/kg of surface-based CAPE along with a precipitable water value of 1.86. Although effective shear is already on the order of 30-40 knots, allowing for modest storm organization and some supercell structures, low-level shear remains tame, with only 50 m2/s2 of low-level SRH on the PBZ sounding. To this point, damaging wind and isolated large hail have been the main severe threats. The tornado threat will increase from here however, and focus more on a corridor between Pittsburgh and I-80. This is where 0-3km CAPE has increased into the 150-175 J/kg range, along with increasing stretching potential and surface vorticity. Along with expected increased hodograph curvature from the approaching shortwave, this will ramp up the potential for tornadoes between 3 PM and 6 PM. The potential for severe thunderstorms will continue to expand southward into the early evening hours to near the Mason-Dixon Line, where the current Severe Thunderstorm Watch continues. CAMs like the NAM3km and HRRR continue to depict a second round of activity approaching from the north after 21Z, associated with the shortwave and an approaching MCV. Clearing behind the initial activity should allow for some recovery of instability across the far north before then, but it may not be as impressive as when activity started a few hours ago. Nevertheless, another round of severe weather is possible in the northern part of the watch area after a possible brief lull of an hour or two. Also of note will be the potential for further instances of flash flooding. East-west training of storms, ample instability, warm cloud depths of up to 12kft, and precipitable water in the 1.6 to 1.9 inch range will continue to support efficient rainfall production and the potential for localized 2-4 inch rainfall totals in 1-3 hours. Storm intensity will begin to tail off after 8-9 PM as daytime heating wanes, but scattered showers and a few thunderstorms are still expected through the night as the shortwave crosses and pushes the frontal boundary to the south. Hot and humid weather this afternoon will produce heat indices in the lower to mid 90s south of the current convective activity. Lows tonight will drop close to seasonable levels. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... KEY MESSAGES: - Shower chances decrease on Wednesday - Dry for most locations through Thursday night, though low shower chances continue east of Pittsburgh __________________________________________________________ Remaining showers and storms will taper from west to east Wednesday as the shortwave and front depart, but some isolated activity may linger into the afternoon in the ridges. Much of the area will then be dry through Thursday night as high pressure builds to the north of the area. However, as the remnants of Debby begin to lift north from the Carolinas, shower chances will remain in the forecast east of Pittsburgh for Thursday and Thursday night. Temperatures should be closer to seasonable levels through the period. && .LONG TERM /FRIDAY THROUGH MONDAY/... KEY MESSAGES: - Unsettled to start, with dry weather later in the period - Cooler temperatures, especially over the weekend _____________________________________________________________ Model ensembles still agree overall on the fate of Debby overall, as it phases with a northern stream shortwave by Saturday. Rain chances increase Friday with the passage of the northern wave, but there is still uncertainty on how quickly the phasing occurs, and that has implications on how far west the edge of the heavier rain travels. Continued to remain close to NBM suggestions, but expect changes in the forecast. Rain chances should diminish Saturday as the initial systems exit. Another shortwave rotating around an upper low across eastern Canada should bring low chances for showers north of I 80 on Sunday, with dry weather returning for Monday and Tuesday under high pressure. Temperatures will fall below normal as the trough lingers. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Medium confidence forecast of 50-60% this afternoon with storm coverage and timing for airports. Higher confidence 70-80% of IFR clouds developing after 6Z and lasting through 14-15Z Wednesday area wide. Scattered to numerous showers and thunderstorms are forecast through this evening. There is disagreement on the CAMS with the timing and location, especially with the main line that will develop just south of Lake Erie. For now, continue with 19Z-23Z timing at most airports and skew it later for MGW. There will be a lull in the activity for part of the evening before isolated to scattered showers form along the front as it drops south into the region. For now, opted not to include any vicinity mention. NBM and LAMP continue with higher probabilities for IFR CIGS and MVFR VIS after 6Z. NBM numbers of CIGS less than 1KFT are between 45-65% with VIS <5SM around the same percentiles. Ongoing forecast already hinted at this and will continue with that trend. Values should stay above threshold B minimums save for FKL and maybe DUJ. IFR lifts into a stratocu field Wednesday with little improvement as northeast wind continues to funnel in cold air advection. In fact, most airports should stay BKN015-025 the duration of the day. Wind will be light less than 10 knots the duration of the forecast. Wind direction starts out westerly than moves to northeast after 0Z. .Outlook... Restrictions are possible again by Friday as moisture streams north along a crossing cold front. VFR should return Saturday as high pressure builds in. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && SYNOPSIS...WM/CL NEAR TERM...CL SHORT TERM...CL LONG TERM...WM/CL AVIATION...McMullen
Hazardous Weather Outlook National Weather Service Pittsburgh PA 1202 PM EDT Tue Aug 6 2024 OHZ039>041-048>050-058-059-PAZ007>009-013>016-020>022-029-031- 073>078-WVZ001>004-071615- Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH- Guernsey-Belmont-Mercer-Venango-Forest-Lawrence-Butler-Clarion- Jefferson PA-Beaver-Allegheny-Armstrong-Washington-Greene- Westmoreland-Higher Elevations of Westmoreland-Fayette- Higher Elevations of Fayette-Indiana-Higher Elevations of Indiana- Hancock-Brooke-Ohio-Marshall- 1202 PM EDT Tue Aug 6 2024 ...SEVERE THUNDERSTORM WATCH 605 IN EFFECT UNTIL 7 PM EDT THIS EVENING... This Hazardous Weather Outlook is for east central Ohio, western Pennsylvania, and northern West Virginia. .DAY ONE...This afternoon and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Severe Thunderstorm Watch. .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. OHZ057-068-069-WVZ012-021-509>514-071615- Muskingum-Noble-Monroe-Wetzel-Marion-Monongalia- Ridges of Eastern Monongalia and Northwestern Preston-Preston- Eastern Preston-Western Tucker-Eastern Tucker- 1202 PM EDT Tue Aug 6 2024 This Hazardous Weather Outlook is for east central Ohio and northern West Virginia. .DAY ONE...This afternoon and tonight. There is a Marginal Risk (or level 1 out of 5) for severe thunderstorms this afternoon and evening. The main hazard is expected to be damaging wind. .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.
Preliminary Local Storm Report
National Weather Service Pittsburgh PA
333 PM EDT Tue Aug 06 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0256 PM Hail Brackenridge 40.61N 79.74W
08/06/2024 E1.00 inch Allegheny PA Public
Observed at 9th Ave and Prospect St
&&
Event Number PBZ2405887
KramarPreliminary Local Storm Report
National Weather Service Pittsburgh PA
334 PM EDT Tue Aug 06 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0255 PM Hail Tarentum 40.61N 79.76W
08/06/2024 M1.00 inch Allegheny PA Trained Spotter
&&
Event Number PBZ2405890
KramarPreliminary Local Storm Report
National Weather Service Pittsburgh PA
335 PM EDT Tue Aug 06 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0252 PM Hail 1 NW Arnold 40.59N 79.78W
08/06/2024 E0.75 inch Allegheny PA Public
&&
Event Number PBZ2405891
KramarPreliminary Local Storm Report
National Weather Service Pittsburgh PA
336 PM EDT Tue Aug 06 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0254 PM Tstm Wnd Dmg Arnold 40.58N 79.76W
08/06/2024 Westmoreland PA 911 Call Center
Trees and wires down in Arnold. Time estimated via
radar.
&&
Event Number PBZ2405893
MLBPreliminary Local Storm Report
National Weather Service Pittsburgh PA
341 PM EDT Tue Aug 06 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0230 PM Tstm Wnd Dmg 1 W Homeacre-Lyndora 40.88N 79.95W
08/06/2024 Butler PA Public
Large limbs broken. Reported via mPING
&&
Event Number PBZ2405894
KramarPreliminary Local Storm Report
National Weather Service Pittsburgh PA
433 PM EDT Tue Aug 06 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0310 PM Tstm Wnd Dmg 1 NNE McCandless Townsh 40.60N 80.02W
08/06/2024 Allegheny PA Public
Tree down along Kummer Road near Hilltop Drive. Time
estimated via radar.
&&
Event Number PBZ2405895
MLBThe Pittsburgh radar (KPBZ), 67 km away, was scanning. The volume nearest the first event began at 21:40 UTC.
1 thunderstorm wind. Local standard time, as filed.
Trees and powerlines were reported down along Beechwood road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Ohio in 2024Every state in 2024This day in weather historyWarnings in Ohio, August 2024
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: 1200937.