A cold front pushed into an unseasonably warm and humid airmass over northwestern Pennsylvania during the evening of September 21, 2018. Moderate shear and CAPE were observed, and the area was under an Enhanced risk from SPC.
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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.
A cold front pushed into an unseasonably warm and humid airmass over northwestern Pennsylvania during the evening of September 21, 2018. Moderate shear and CAPE were observed, and the area was under an Enhanced risk from SPC. Farther to the east, a moist southeasterly flow maintained low clouds through the day and conditions were much more stable.
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 Sep 21, 4:31 PM EST, 43 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 531 PM EDT Fri Sep 21 2018 .SYNOPSIS... A line of severe thunderstorms capable of strong to potentially damaging wind gusts are likely to impact northwest and north central Pennsylvania later this evening into early tonight. A refreshingly cooler and less humid airmass will kick- off the fall season on Saturday with dry weather persisting in most areas through the remainder of weekend. Periods of rain are likely to return Monday night into the middle of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 18Z GOES-16 visible satellite continues to show low clouds hanging tough over the eastern 1/2 of the CWA. Meanwhile, mostly sunny, warm and breezy conditions are common across the western Alleghenies to the OH border. Radar and satellite trends now confirm a pre-frontal boundary exists from western NY extending southward along the Allegheny Front, enhanced to some extent by differential heating on the edge of the low clouds. Earlier runs of the hires models did a reasonable job in depicting isolated convection developing in the lee of the Alleghenies. The main focus remains the late-day severe/damaging wind threat associated with well-defined cold front moving eastward through the Great Lakes and Ohio Valley. The damaging wind threat will arise from a relatively fast-moving line of thunderstorms (QLCS) forecast to develop by CAMS along/ahead of the cold front, accelerating southeastward downwind of Lake Erie across northwest PA into north central PA later this evening into early tonight. The most likely timing for severe wind gusts is 23Z and 03Z over the northwest 1/3 of the CWA. The line should gradually weaken and lose intensity as it continues to push southeast of I-80/99 early tonight. The threat of severe weather will also decrease, owing to limited instability and downsloping flow east of the Alleghenies. Gusty winds will remain possible along the front. Models show frontal precip breaking up and progressively dissipating into the predawn hours Saturday over the southeast 1/3 of the CWA or near the PA Turnpike. Noticeably cooler and much drier air will overspread the area from north to south late tonight. Expect temperatures around daybreak Saturday to range from the upper 40s in the northern tier to around 60 degrees in the lower Susquehanna Valley. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Cooler, less humid air will arrive behind the front for the upcoming weekend. The frontal boundary will stall just south of the Mason-Dixon line, with fair weather persisting through Saturday evening. Models hinting at moisture riding along the Mason Dixon line Saturday night into Sunday, keeping light rain going there for the second half of the weekend. && .LONG TERM /MONDAY THROUGH FRIDAY/... Model consensus supports increasing forecast confidence in a period of rain developing north to south Monday night into Tuesday as the wavy frontal boundary lifts back to the north aided by return flow around 1039 mb sfc high over Nova Scotia. There is also growing confidence/certainty in rainfall along a cold front crossing the Appalachians around mid week. Following a dry period Thursday and early Friday a second cold front looks possible later Friday. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... Late afternoon update, minor adjustments. Line of storms heading toward BFD, 40 knot gust at Erie, already have this in the BFD TAF. Low clds holding tight across the east, backed off on the low clds lifting some, prior to any shower activity late. Earlier discussion below. MVFR ceilings holding tough over the eastern 1/2 of the airspace while VFR prevails across ZOB sector. Growing less optimistic for improvement in the eastern airspace. An isolated shower or thunderstorm will be possible through the late afternoon. Winds will remain a bit gusty (15-25KT) especially across the western airspace through the evening. A relatively fast-moving line of gusty showers/storms will accompany a cold front southeastward through the airspace late this evening through tonight. The greatest risk for high wind gusts exists over the northwest airspace and included TEMPO group with 40KT gust at KBFD btwn 00-02Z. Low clouds should move in behind the cold front late tonight with MVFR cigs a good bet across the northwest 1/3 of the airspace into early Saturday morning. .Outlook... Sun...AM fog north. Light rain possible near the PA/MD border. Mon-Tue...Periods of rain spreading south to north. Wed...Showers/thunderstorms likely. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Ross/DeVoir/Steinbugl LONG TERM...Gartner/Steinbugl AVIATION...Martin/Steinbugl
Hazardous Weather Outlook National Weather Service State College PA 512 PM EDT Fri Sep 21 2018 PAZ004>006-010-011-017-222115- Warren-McKean-Potter-Elk-Cameron-Clearfield- 512 PM EDT Fri Sep 21 2018 ...SEVERE THUNDERSTORM WATCH 387 IN EFFECT UNTIL 11 PM EDT THIS EVENING... This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...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...Saturday through Thursday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ012-018-019-024>026-033>035-037-041-045-046-222115- Northern Clinton-Northern Centre-Southern Centre-Cambria-Blair- Huntingdon-Somerset-Bedford-Fulton-Tioga-Northern Lycoming- Southern Clinton-Southern Lycoming- 512 PM EDT Fri Sep 21 2018 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Tonight. A line of strong to marginally severe thunderstorms with gusty winds will move through the region late this evening into early tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ027-028-036-042-049>053-056>058-063-222115- Mifflin-Juniata-Franklin-Sullivan-Union-Snyder-Montour- Northumberland-Columbia-Perry-Dauphin-Schuylkill-Cumberland- 512 PM EDT Fri Sep 21 2018 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Tonight. A line of showers with gusty winds will move through the region between 1030 pm and 2 am. A thunderstorm with brief heavy rain is also possible within this line. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ059-064>066-222115- Lebanon-Adams-York-Lancaster- 512 PM EDT Fri Sep 21 2018 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. Lambert
The Buffalo radar (KBUF), 128 km away, was scanning. The volume nearest the first event began at 22:12 UTC.
7 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree and wires across Route 6 near Swamp Run.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree and wires along Davey Hill Road.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees in Bradford Township.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires near Lewis Run.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree across Route 6 on Hazel Hurst Hill in Hamlin Township.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees in Hastings.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees in East Carroll Township.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2018Every state in 2018This day in weather historyWarnings in Pennsylvania, September 2018
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: 779087, 779088, 779089, 779090, 779091, 779092, 779093.