An afternoon trough passage supported a few clusters of thunderstorms in an environment characterized by 1000-2000 J/kg of surface-based instability and up to 1500 J/kg of downdraft CAPE. This supported the development of downdraft-aided wind gusts that caused several instances of damage.
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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.
An afternoon trough passage supported a few clusters of thunderstorms in an environment characterized by 1000-2000 J/kg of surface-based instability and up to 1500 J/kg of downdraft CAPE. This supported the development of downdraft-aided wind gusts that caused several instances of damage.
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 15, 12:27 PM EST, 37 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 127 PM EDT Mon Jul 15 2024 .SYNOPSIS... Multiple chances of storms with severe potential will arrive this afternoon, early Tuesday morning, and Tuesday afternoon. A passing cold front Wednesday will keep storm chances, and bring temperatures closer to normal. A warming trend is expected into the weekend. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - There is a 1 out of 5 risk of severe weather this afternoon and late tonight. - Heat indices well into the 90s will maintain heat risk concerns. __________________________________________________________________ Morning observations show dew points running a bit lower than the prior forecast, so opted to nudge values down slightly into the day today. Nonetheless, there is minimal low-level dry air to tap into today. Combined with mostly clear-sky radiative heating for most into the low 90s and upper 80s, the current forecast calls for apparent temperatures well into the mid 90s. Thus, a heat advisory was not issued for today. Nonetheless, valleys, urban centers, and areas south of I-70 may peak in the afternoon with a few hours where apparent temperature is in the upper 90s. The secondary threat today will be the 1 out of 5 risk of severe weather. The prominent MCV embedded within a shortwave is expected to pass well off to the north through Buffalo today, where the primary threat is centered. Weak PVA in the mid-level trough passes through this afternoon, primarily between 4pm and 9pm, providing the most likely, but still lack-luster, forcing for initiation. With broad ascent, coverage is expected to be spotty, if at all. There is roughly a 50% to 70% chance that bulk shear remain below 20kts south of I-80, with 20kts-30kts favored north of I-80. With high confidence in surface-base instability ranging from 1000-2000 J/kg, convective character may tend to resolve to more pulse convection than anything else. Mid-level dry air will act as a double edged sword to convection. If healthy updrafts develop, they may utilize 1000-1500 J/kg DCAPE, though that is conditional. On the flip side, the dry air may limit updraft development, especially with weaker forcing. That being said, wind will remain the primary threat today within the collapse of mature storms. This is conditional on storm formation. Tonight, a brief reprieve in precipitation is expected before a weak wave may allow for nocturnal convection ahead of a decaying MCS. All ensemble guidance supports that this rebound will remain elevated, which may suggest low severe potential, but there is still a low chance that these become surface-based with cold pool development. Most likely timing is between 2am and 8am. Winds once again remain the primary threat. Nocturnal hodographs do look impressive, but this is largely a result of the implied decoupling. Should storms become surface based, tornadoes remain possible, but the shear profile would tend a tad weaker, and most of the instability is not packed in the low-levels. At this time, the tornado threat is unlikely, but could not be ruled out. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Active weather with several convective rounds presenting potential severe hazards until the passage of a cold front on Wednesday. - Continued well above normal temperatures. _________________________________________________________________ Uncertainty in the forecast continues as upstream development will largely dictate our weather until the passage of a Wednesday cold front. Further rounds of convection are expected but timing is uncertain. Damaging wind will continue to be the primary threat mode. A more stout shortwave trough dropping into the Great Lakes on Wednesday will finally help to push a cold front along for an eventual Wednesday afternoon/night passage, bringing a more concentrated precipitation area Wednesday, but then an end to the convective threat behind it. Heat and humidity will continue to be part of the story during the early part of the week. The potential for advisory-level heat index values of 100 or more on Tuesday depending on convective extent and timing. With 850mb temperatures expected to reach or exceed 20C over a good portion of the region, a lack of cloud cover could lead to sufficient sunshine to get surface temperatures into the mid 90s for some on either day, leading to the higher heat index values. However, more abundant cloud cover could keep temperatures below 90 and therefore stunt the heat impact. Due to this, will hold off on any heat-related headlines for now, hoping that time and additional near-term information will lead to increased clarity. More concentrated clouds and precipitation on Wednesday should limit heating below advisory thresholds. && .LONG TERM /THURSDAY THROUGH MONDAY/... KEY MESSAGES: - A drier and cooler pattern will ensue on Thursday and continue into next weekend. ------------------------------------------------------------------- The cold front should complete its passage Thursday morning, perhaps stalling over the Central Appalachians/Middle Ohio Valley, with expanding high pressure across the Great Lakes and northeast CONUS into next weekend. Drier weather and cooler temperatures, perhaps falling a few degrees below normal, can be expected through Friday night. The shallow upper troughing in place Thursday and Friday may be replaced by rising heights Saturday/Sunday in response to increased troughing over the Central Plains. This could also bring moisture back from the south, leading to increased diurnal precipitation chances, mainly southeast of Pittsburgh. A warmup back to seasonable temperatures can also be anticipated. && .AVIATION /18Z MONDAY THROUGH FRIDAY/... A weak mid-level mesoscale convective vortex (MCV) is moving through the area to start the TAF period, bringing with it a BKN/OVC mid-level cloud deck with cigs around 15kft and a scattered cu field with cigs around 4-5kft. Away from this feature, most of the area remains under mostly clear skies with only a few high clouds and/or fair weather cu to note. Low (but non-zero) chances for showers and thunderstorms continue through the late afternoon and early evening, possibly focused along the leading southeast edge of the aforementioned MCV as it tracks towards the ridges southeast of PIT. Better rain chances are expected during the pre-dawn hours Tuesday, between roughly 06Z-12Z, when a weak disturbance moves through the area ahead of a decaying MCS. Elevated instability should support a few rumbles of thunder intermixed with the heavier showers. Morning convection clears the area around or shortly after 12Z, giving way to a lull in activity through the rest of the morning before more showers and storms are expected to develop just beyond the TAF period Tuesday afternoon. Southwest winds remain breezy this afternoon, around 10-15 knots with gusts up to 20-25 knots. Winds then relax some tonight before picking back up Tuesday, possibly stronger with gusts closer to 30 knots. .Outlook... Periodic shortwave troughs lead to thunderstorm chances through mid-week, peaking Tue into Wed with the approach and passage of a cold front. Timing and coverage will be difficult to predict due to the strong impact of prior days' convective evolution on moisture, instability, and ascent. High pressure is favored Thu through the end of the week with high confidence VFR and dry weather. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && SYNOPSIS...Milcarek NEAR TERM...Milcarek SHORT TERM...CL/88 LONG TERM...CL AVIATION...Cermak
Hazardous Weather Outlook National Weather Service Pittsburgh PA 157 PM EDT Mon Jul 15 2024 OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>022-029- 031-073>078-WVZ001>004-012-021-509>514-161800- Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH- Muskingum-Guernsey-Belmont-Noble-Monroe-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-Wetzel- Marion-Monongalia- Ridges of Eastern Monongalia and Northwestern Preston-Preston- Eastern Preston-Western Tucker-Eastern Tucker- 157 PM EDT Mon Jul 15 2024 This Hazardous Weather Outlook is for east central Ohio, western Pennsylvania, and northern West Virginia. .DAY ONE...This afternoon and tonight. Damaging wind gusts will be possible with stronger thunderstorms this afternoon and early evening. There is a low chance of damaging winds late tonight, an isolated spin up could not be ruled out. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Strong to severe storms are anticipated to track through the region again on Tuesday. Damaging wind gusts will again be the main threat, but large hail, a few tornadoes, and flash flooding will all be possible as well. If strong to severe storms are absent across the region on Tuesday, there is the potential for dangerous heat. Max temperatures could range in the mid to upper-90s and heat indices could range from 100F to 105F. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures. Milcarek
Special Weather Statement
National Weather Service Pittsburgh PA
159 PM EDT Mon Jul 15 2024
PAZ014-151830-
Butler PA-
159 PM EDT Mon Jul 15 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN BUTLER COUNTY THROUGH
230 PM EDT...
At 159 PM EDT, Doppler radar was tracking a strong thunderstorm near
Meridian, or near Butler, moving east at 25 mph.
HAZARD...Wind gusts up to 50 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Butler, Homeacre-Lyndora, Shanor-Northvue, Meridian, Meadowood, Oak
Hills, Nixon, East Butler, and Connoquenessing.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4074 8003 4083 8008 4093 7983 4080 7974
TIME...MOT...LOC 1759Z 248DEG 20KT 4080 7999
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
MilcarekThe Pittsburgh radar (KPBZ), 44 km away, was scanning. The volume nearest the first event began at 18:04 UTC.
9 thunderstorm wind. Local standard time, as filed.
A large tree was blown down on to McQuistion Road.
Trees and wires were blown down.
A tree was downed on to Highway 66 near Mechanicsville.
Near New Bethlehem, trees and wires were blown down.
Trees and wires were blown down in the vicinity of Brookville.
Trees and wires were downed in Brockway.
Trees and power lines were downed in Westmoreland City.
Trees were blown down in the vicinity of Manor.
At least 10 trees were blown down with tops sheared off.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2024Every state in 2024This day in weather historyWarnings in Pennsylvania, July 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: 1200803, 1200804, 1200805, 1200806, 1200807, 1200808, 1200809, 1200810, 1200811.