Convection across southern Pennsylvania began to develop in an unstable and moist environment ahead of a shortwave trough traversing the area during the afternoon and evening hours of July 9, 2025. Storms initially were sub-severe due to lower shear parameters and low-level lapse rates; however, increasing shear and lapse rates allowed for damaging wind potential within an environment of 700-900…
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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 CTP wrote it up.
Convection across southern Pennsylvania began to develop in an unstable and moist environment ahead of a shortwave trough traversing the area during the afternoon and evening hours of July 9, 2025. Storms initially were sub-severe due to lower shear parameters and low-level lapse rates; however, increasing shear and lapse rates allowed for damaging wind potential within an environment of 700-900 J/kg of DCAPE. Shear oriented out of the southwest, parallel to surface boundaries, led to an increased risk of flash flooding in an environment that sustained over one inch an hour rainfall rates. Multiple instances of trees and wires being knocked down were reported in Lancaster and York counties during the evening hours. Increased rainfall rates falling over fairly moist soils of York County induced flash flooding, with multiple roadways closed in both counties during the evening hours. Heavy rain also caused a basement to collapse in Dover, with water and mud reported over nearby roadways.
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 Jul 9, 2:21 PM EST, 51 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 321 PM EDT Wed Jul 9 2025 .SYNOPSIS... * Scattered damaging wind gusts and flash flooding are possible across portions of south central and southeastern Pennsylvania this afternoon and evening * Continued seasonably warm and humid into mid July with daily chances for afternoon and evening thunderstorms && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Latest satellite and radar trends show convection developing and intensifying along multiple convergence boundaries ahead of a northeastward moving shortwave trough. Thus far, storms have remained below severe limits, but we do see the chance for damaging winds increasing into the early evening hours across the southern tier, where low level lapse rates are above 7C/km, MLCAPE is near 1500 J/kg, and DCAPE is between 700 and 900 J/kg. Effective wind shear is around 40 kts from the SW. This direction aligns with the orientation of many of the initiating boundaries, particularly those along the higher terrain of the central Appalachians. The alignment of the shear (and the flow) with the initiating boundaries increases the threat for training convection and ultimately flash flooding. Thus the Flash Flood Watch and Severe Thunderstorm Watch continue for the southeastern tier. Convection will likely be slow to clear out of Lancaster County, with some of the guidance depicting moderate to heavy rain continuing as late as midnight before the trough kicks it east. For the rest of the night, patchy fog is possible, particularly in places that see some clearing after earlier rainfall. Temperatures will be in the 60s to near 70 degrees. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... Diurnal heating of a seasonably moist and weakly capped boundary layer will result in at least isolated to scattered afternoon thunderstorms across central PA again on Thursday and Friday. However, precipitable water values look to trend lower vs. previous days. This will reduce the excessive rainfall and flash flood risk while remaining sufficient to support the potential for wet downbursts and isolated wind damage. SPC has maintained a MRGL risk for both D2/Thu and D3/Fri. Typical mid July summertime temperatures expected with daytime highs in the 80-90F range and lows 60-70F. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Daily chances for afternoon/evening thunderstorms continue over the weekend and into early next week with max/min temps trending near to slightly above normal for mid July. Tuesday may stand the highest chance of being a completely dry day, but even then, PoPs are 20-35 pct. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... Variable cloudiness is expected this afternoon with scattered mid level clouds area wide and a deck of high level clouds moving in across the northwest. VFR conditions will prevail until scattered showers and thunderstorms begin to build later this afternoon and evening. A few light showers are possible at JST and AOO, perhaps even as far north as UNV, but any restrictions should be brief. Farther southeast, heavier showers and stronger storms are expected in MDT and LNS between 22 and 02Z with reductions to MVFR or IFR vis expected as storms move through. The forecast for tonight gets a bit more complicated in terms of cigs and vis. High clouds should limit the potential for radiation fog tonight, but moisture pooling as a result of recent rains could still lead to some fog/low ceiling potential. At this point, the best chance for radiation fog will be BFD and JST where clearing may build in before daybreak. Have indicated at least a period of MVFR restrictions at all airfields tonight, but confidence remains fairly low in the extent and duration of such impacts. Outlook... Thu...Restrictions in possible in scattered PM storms. Fri-Sat...Scattered afternoon/evening storms, mainly south. Sun...More widespread showers/storms likely. Mon...Still storms around. && .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch until 11 PM EDT this evening for PAZ064>066. && SYNOPSIS...Steinbugl/Colbert NEAR TERM...Steinbugl/Colbert SHORT TERM...Steinbugl/Colbert LONG TERM...Lambert/Colbert AVIATION...Banghoff
Hazardous Weather Outlook National Weather Service State College PA 220 PM EDT Wed Jul 9 2025 PAZ004>006-010>012-017>019-024>028-033-037-041-042-045-046-049>053- 056>059-063-101830- Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield- Northern Centre-Southern Centre-Cambria-Blair-Huntingdon-Mifflin- Juniata-Somerset-Tioga-Northern Lycoming-Sullivan-Southern Clinton- Southern Lycoming-Union-Snyder-Montour-Northumberland-Columbia-Perry- Dauphin-Schuylkill-Lebanon-Cumberland- 220 PM EDT Wed Jul 9 2025 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Isolated severe storms containing damaging winds are possible during the afternoon and evening on Thursday and Friday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. PAZ034>036-101830- Bedford-Fulton-Franklin- 220 PM EDT Wed Jul 9 2025 ...SEVERE THUNDERSTORM WATCH 497 IN EFFECT UNTIL 10 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. Severe Thunderstorm Watch. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Isolated severe storms containing damaging winds and heavy rain are possible during the afternoon and evening on Thursday and Friday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ064>066-101830- Adams-York-Lancaster- 220 PM EDT Wed Jul 9 2025 ...SEVERE THUNDERSTORM WATCH 497 IN EFFECT UNTIL 10 PM EDT THIS EVENING... ...FLOOD WATCH IN EFFECT UNTIL 11 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. Severe Thunderstorm Watch. Flood Watch. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Isolated severe storms containing damaging winds and heavy rain are possible during the afternoon and evening on Thursday and Friday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather.
The Sterling radar (KLWX), 142 km away, was scanning. The volume nearest the first event began at 20:12 UTC.
7 thunderstorm wind, 5 flash flood. Local standard time, as filed.
A severe thunderstorm producing wind gusts estimated at 70 mph blew the roof off of a structure approximately 4 miles northwest of Safe Harbor. Multiple trees were also knocked down.
Flash flooding led to a vehicle taking on water at the intersection of West Market Street and Kreutz Creek Road in Hallam.
A severe thunderstorm producing wind gusts estimated at 60 mph knocked wires down onto Lake Road approximately 1 mile east of Jacbous.
A severe thunderstorm producing wind gusts estimated at 60 mph knocked trees and wires down at the intersection of Blue Ridge Drive and Oak Ridge Drive in Millersville.
A severe thunderstorm producing wind gusts estimated at 60 mph knocked trees and wires down at the intersection of New Danville Pike and Marticville Road near Millersville which caused a brief closure of PA-741.
A severe thunderstorm producing wind gusts estimated at 60 mph knocked trees and wires down at the intersection of Beaver Valley Pike and Penn Grant Road in Willow Street.
Flash flooding covered a roadway with debris in Hellam Township.
A line of severe thunderstorms producing wind gusts estimated at 60 mph knocked a tree down onto Cross Roads Avenue approximately 3 miles southeast of Winterstown.
A line of severe thunderstorms producing wind gusts estimated at 60 mph knocked a tree down onto Century Farms Road approximately 2 miles southeast of Felton.
Flash flooding was observed from the creek along Rippling Run Road between Felton and Winterstown.
Flash flooding led to a basement foundation collapse in the 1700 block of Oakley Drive near Weigelstown, with water and mud reported across roadways in the area.
Flash flooding pushed water across the bridge at Herbst Road near Felton.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2025Every state in 2025This day in weather historyWarnings in Pennsylvania, July 2025
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 2026-09-30. Each event’s entry at NCEI: 1276110, 1278555, 1276112, 1276117, 1276119, 1276120, 1278557, 1276121, 1276122, 1278558, 1278561, 1278563.