High CAPE (>2500 J/kg) and strong speed and directional shear contributed to a significant severe weather episode across south-central Pennsylvania during the afternoon and evening of August 7, 2023. Of note, a significant bow echo produced widespread wind damage and a trio of weak (EF0-EF1) tornadoes across southern York and Lancaster Counties.
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 CTP wrote it up.
High CAPE (>2500 J/kg) and strong speed and directional shear contributed to a significant severe weather episode across south-central Pennsylvania during the afternoon and evening of August 7, 2023. Of note, a significant bow echo produced widespread wind damage and a trio of weak (EF0-EF1) tornadoes across southern York and Lancaster Counties.
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 State College, PA wrote its last area forecast discussion before the first event at Aug 7, 12:18 PM EST, 18 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 118 PM EDT Mon Aug 7 2023 .SYNOPSIS... Dangerous thunderstorms with damaging to locally destructive winds, large hail, and torrential downpours are possible this afternoon and evening across the southeastern half of central Pennsylvania. Turning breezy and less humid Tuesday with showers possible mainly over the northern tier. Dry weather is likely Tuesday night through Wednesday. Looking ahead into the late week and weekend periods, the highest odds for rain at this time are on Thursday and Saturday. && .NEAR TERM /THROUGH TONIGHT/... 1220PM/1620UTC: Update concerning severe weather potential per SPC MD#1879. A tornado watch is likely to be issued in the next hour or so pending favorable convective trends. Probability of watch issuance is 95 percent. Ample destablization ongoing late the morning with SBCAPE values >2000 j/kg across south central PA. The aforementioned buoyancy coupled with strong low and mid/upper level wind fields will support appreciable severe threat developing through the afternoon. Storm mode evolution continues to favor discrete supercells transitioning to QLCS. Damaging winds remain the most likely t-storm hazard with a few 65+ kt gusts possible. Tornado potential will exist with any supercell structures and stronger QLCS circulations. 1045AM/1445UTC: Small t-storm line segment with ltg and brief heavy rainfall moving quickly to the northeast into the middle to upper Susquehanna Valley. This activity is associated with MCV swirling from northeast OH into northwest PA. Beyond this convection, not expected much additional development until this afternoon. Severe thunderstorm risk for later today has increased with an upgrade by SPC to moderate or level 4 out of 5 now extending into far southern/southeast PA. For historical context, this is the first moderate risk in central PA since July 8, 2014 (3,317 days) and first moderate risk in all of PA since May 15, 2018 (1,910 days). Significant damaging winds are expected in this area with localized gusts above 70 mph possible. Storm mode is expected to transition from supercells to a QLCS/squall line as t-storms move eastward across and downwind of the higher terrain. Storm intensity is ramping up to the southwest across parts of OH and KY. While damaging winds are the primary threat, large hail and a few tornadoes are also possible. The wind fields and shear magnitudes are rather impressive for early August, which is not surprising given the unseasonably strong/anomalous low pressure system (-2 to -3SD below the mean) tracking from the OH Valley to the north of PA. Previous Discussion: Model soundings indicate early low clouds should give way to brightening skies later today, as the region breaks into the warm sector ahead of low pressure tracking across the lower Grt Lks. Heating of the moist/unstable airmass, combined with strong shear ahead of an upstream trough, will set the stage for a severe weather threat during the PM hours. The strongest mid level flow and best chance of severe weather appears focused over the southern tier counties. However, deep layer shear of 40kts+, combined with MLCAPE in the 1000-2000 J/kg range, will support a risk of all severe hazards over a good portion of Central PA. The amount of deep and low level shear supports supercells and the potential of an isolated tornado. Much of the convection- allowing guidance indicates upscale growth into a MCS during the afternoon, which could also spawn a brief/weak tornado given progged 0-3km shear vectors, which are 30-40kts and oriented nearly perpendicular a north-south oriented squall line. Instability and pwats surging to near 2 inches supports torrential downpours with any storms this afternoon. However, latest guidance suggests storm motions will limit the threat of flash flooding. The 00Z HREF indicates spot amounts between 2-3 inches are likely, but given the latest FFG numbers that amount of rain would probably produce minor flooding rather than significant flash flooding. The severe weather threat may last into this evening over the eastern counties, then expect the storms to wind down overnight, as the best upper level diffluence and plume of deepest moisture shifts east of the state. Scattered showers will remain possible associated with the passage of the cold front, primarily over the Allegheny Plateau. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... A relatively cool and breezy Tuesday appears likely for Central PA, as unseasonably strong low pressure passes north of the state. Passage of the upper trough should support mainly cloudy skies and scattered showers across the N Mtns, with brighter skies and only an outside chance of a shower in the south. Bukfit soundings indicate wind gusts between 25-30kts are likely from late morning into the afternoon hours. Ensemble mean 850mb temps around 13C supports highs mostly in the 70s. Fair weather and a diminishing wind is expected Tuesday night, as the low pulls away, then fair and seasonable conditions appear likely Wednesday as surface ridging and its associated low-pwat air mass build into PA. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Wednesday will see dryer conditions as upper-level zonal flow takes over for the day. The dry air coming in behind the remnants of Tuesdays storms will keep dewpoints down and provide comfortable conditions. The next system will arrive on Thursday as a shortwave disturbance approaches from the Ohio Valley during the early afternoon hours. This trough will provide enough synoptic lift and moisture to promote the development of scattered showers and thunderstorms. Friday looks to be seasonable and generally dry, before an approaching upper-level trough and weak cold front reintroduces the chance of at least diurnal showers/storms for the weekend. Temperatures should remain seasonable through the extended. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... Convective showers and thunderstorms are forming across western PA ahead of a potent cold front that will bring SHRA/TSRA to central PA this afternoon and evening. Signals are in place for widespread restrictions as showers and thunderstorms traverse across CPA. TSRA will bring potential for gusty winds, heavy rainfall impacting visibility, and hail across central PA with an isolated tornado possible across the southern tier. SHRA will continue into the overnight hours before some clearing, although restrictions are still expected to be MVFR- to-IFR at this time. Fog is possible to bring vis/cigs down even further, but there is not enough confidence at this time to outline in the forecast package. Outlook... Tue...Scattered -SHRA, isolated TSRA remain poss. Wind gusts to 30+ mph poss across the SW. Tue night-Wed...AM fog poss, otherwise VFR. Thurs...Scattered SHRA/TSRA, with brief restrictions poss. Fri...Generally VFR. Isolated PM SHRA/TSRA, with brief restrictions poss. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...Steinbugl NEAR TERM...Fitzgerald/Steinbugl SHORT TERM...Fitzgerald LONG TERM...Bowen AVIATION...Travis/NPB
Hazardous Weather Outlook National Weather Service State College PA 123 PM EDT Mon Aug 7 2023 PAZ006-011-012-017>019-024>028-033>037-041-042-045-046-049>053- 056>059-063>066-081730- Potter-Cameron-Northern Clinton-Clearfield-Northern Centre- Southern Centre-Cambria-Blair-Huntingdon-Mifflin-Juniata-Somerset- Bedford-Fulton-Franklin-Tioga-Northern Lycoming-Sullivan- Southern Clinton-Southern Lycoming-Union-Snyder-Montour- Northumberland-Columbia-Perry-Dauphin-Schuylkill-Lebanon-Cumberland- Adams-York-Lancaster- 123 PM EDT Mon Aug 7 2023 ...TORNADO WATCH 602 IN EFFECT UNTIL 9 PM EDT THIS EVENING... This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Tornado Watch. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ004-005-010-081730- Warren-McKean-Elk- 123 PM EDT Mon Aug 7 2023 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. A few strong thunderstorms with isolated damaging winds are possible this afternoon. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. MRS
Special Weather Statement National Weather Service State College PA 104 PM EDT Mon Aug 7 2023 PAZ033>036-064-071815- Somerset-Bedford-Fulton-Franklin-Adams- 104 PM EDT Mon Aug 7 2023 ...SEVERE WEATHER EXPECTED TO ARRIVE IN THE SOUTHERN TIER OF CENTRAL PENNSYLVANIA IN THE NEXT HOUR... Severe storms are expected to arrive between 1 and 2 PM this afternoon. There is a significant threat for damaging winds, along with the potential for large hail and a few tornadoes. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. If a Severe Thunderstorm Warning or Tornado Warning is issued for your area, move to a place of safety, ideally in an interior room on the lowest level of a sturdy building. MRS
The Sterling radar (KLWX), 111 km away, was scanning. The volume nearest the first event began at 17:33 UTC.
36 thunderstorm wind, 5 flood, 3 hail. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph knocked down power poles and trees across Path Valley Road and Main Street in Fort Loudon.
A severe thunderstorm produced quarter-sized hail near Fort Loudon.
A severe thunderstorm producing winds estimated near 60 mph knocked a tree across Halfmoon Valley Road southwest of Stormstown.
A severe thunderstorm produced golf ball sized hail near Metal.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees in Meyersdale.
A severe thunderstorm producing winds estimated near 60 mph knocked down a large tree on the southwestern end of State College.
A severe thunderstorm produced quarter-sized hail on the northwest side of Centre Hall.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees along Anthony Highway south of Quincy.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees around Clearville.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees across Mallard Run Road east of Buck Valley.
A severe thunderstorm producing winds estimated near 60 mph knocked down road signs and blew them across Interstate 70 south of Crystal Spring.
A thunderstorm producing winds estimated near 50 mph knocked down tree limbs that fell onto and destroyed a chicken coop north-northeast of Woodland.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires throughout Hamilton Township.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree across Red Hill Road southeast of New Oxford.
A severe thunderstorm moved across southern Union County on the afternoon of August 7th, 2023. This thunderstorm caused a swath of straight line wind damage in Union Township just south of State Route 304. Damage began roughly 150 yards south of Route 304 in a wooded area where several trees were snapped or uprooted. The|storm then moved across Amish Rd and destroyed an outbuilding. Several trees were also snapped or uprooted in the vicinity of the outbuilding. Tree damage extended to a wooded area along Felmey Rd as well. The trees were largely laying in the same direction as was debris from the damaged outbuilding, consistent with straight|line wind damage.
Water flowing across the roadway led to the closure of Route 45 west of Mifflinburg.
Flooding led to the closing of roads in Lewisburg, as Limestone Run left it's banks in the vicinity of 15th Street and Saint Mary's Street.
Flooding caused possible damage to the Loomis Street Bridge in Lewisburg.
Flooding caused possible damage to the a bridge on Turtle Creek Road near in Lewisburg.
Flooding led to a washed out culvert on Felmey Road near Winfield, closing the road until repairs can be made.
A severe thunderstorm producing estimated winds near 60mph knocked down trees onto Route 15 east of Greenmount.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree across Baltimore Pike south of Parkville, blocking the road.
A severe thunderstorm producing winds estimated near 70 mph knocked down numerous trees and powerlines in the Black Rock area.
A severe thunderstorm producing winds estimated near 60 mph knocked down numerous trees north of Bloomsburg.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto wires north of Elysburg.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees in Shrewsbury, with one falling onto a vehicle and causing one injury.
A severe thunderstorm producing winds estimated near 70 mph blew the roof off of a pole barn and blew a garage door in.
A severe thunderstorm producing winds estimated near 75 mph knocked down high tension power lines north of Stewartstown.
A severe thunderstorm producing winds estimated near 80 mph uprooted and snapped multiple trees along Harvey Court north of Shrewsbury, with tree debris across the roadway.
A severe thunderstorm producing winds estimated near 70 mph produced numerous reports of trees down and widespread damage in Stewartstown.
A severe thunderstorm producing winds estimated near 60 mph snapped 3 inch diameter tree limbs, and snapped power poles.
A severe thunderstorm producing winds estimated near 70 mph knocked down several trees and large limbs near New Salem.
A severe thunderstorm producing winds estimated near 75 mph knocked down produced significant damage, including structural damage, on the 14000 block of Sally Ann Road near Cross Roads.
A severe thunderstorm producing winds estimated near 80 mph produced extensive tree damage with trees uprooted and snapped. A considerable amount of tree damage was strewn across roadways. Additionally, a chicken coop was crushed and a sheet metal barn had it's roof partially torn off. The duration of the strong winds was more than 5 minutes.
A severe thunderstorm producing winds estimated near 75 mph knocked down numerous trees, blocking several roadways north of Fawn Grove.
A severe thunderstorm producing winds estimated near 70 mph snapped or uprooted more than 20 trees mostly soft wood trees, some 50-60 feet in height.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree, completely blocking Park Street between Brighton Drive and Ness Court in Loganville.
A severe thunderstorm producing winds estimated near 60 mph produced isolated tree damage and knocked down large (3 inch diameter) limbs to the east of Susquehanna Trails.
A severe thunderstorm producing winds estimated near 75 mph produced multiple reports of roofs off of buildings east of Holtwood.
A severe thunderstorm producing winds estimated near 70 mph knocked down a tree onto a home and a barn was also damaged by the wind.
A severe thunderstorm producing winds estimated near 70 mph knocked down multiple trees across Springfield Township.
A severe thunderstorm producing winds estimated near 70 mph knocked down trees, causing considerable damage to a home east of Susquehanna Trails.
A severe thunderstorm producing winds estimated near 60 mph knocked down snapped limbs and power lines south of Bloomsburg.
A severe thunderstorm producing winds estimated near 75 mph knocked down trees in a yard and produced a lot of tree debris in the yard and adjacent roadway. The duration of the strong winds was nearly 5 minutes.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2023Every state in 2023This day in weather historyWarnings in Pennsylvania, August 2023
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: 1121882, 1120286, 1121907, 1120297, 1121922, 1121917, 1120301, 1122216, 1121923, 1122290, 1122304, 1122579, 1122568, 1122580, 1128503, 1119669, 1117356, 1128483, 1128486, 1128490, 1122585, 1128429, 1128434, 1128443, 1128441, 1128430, 1128449, 1128451, 1128462, 1128433, 1128444, 1128447, 1128435, 1128459, 1128438, 1128472, 1128454, 1128464, 1128437, 1128439, and more.