A broken line of showers and thunderstorms developed in a moderate CAPE and weak to moderate shear environment south of a weak frontal boundary that was draped over northern Pennsylvania during the evening of September 13, 2021. One particular cell along this line intensified over Lycoming County and produced sporadic wind damage as it progressed southeastward across eastern Lycoming, Columbia…
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.
A broken line of showers and thunderstorms developed in a moderate CAPE and weak to moderate shear environment south of a weak frontal boundary that was draped over northern Pennsylvania during the evening of September 13, 2021. One particular cell along this line intensified over Lycoming County and produced sporadic wind damage as it progressed southeastward across eastern Lycoming, Columbia and eastern Schuylkill 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 Sep 13, 1:49 PM EST, 4 hours 21 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 249 PM EDT Mon Sep 13 2021 .SYNOPSIS... A front will become nearly stationary over northern and central PA this evening. It will slowly return northward Tuesday. A cold front will try to move through on Wednesday. An upper level ridge will be building over the eastern states, and will likely stall the front out overhead or deflect it to the north. && .NEAR TERM /THROUGH TONIGHT/... The vort max driving the cluster/bow echo of storms rolling over DTX will continue to the east steadily and quickly this afternoon and evening. The cold front is in the process of stalling out over nrn PA. It could sag a little more to the south, but not far past a FIG- UNV-SEG line. Shear aloft in the lowest 10kft is respectable. Capping in mid levels and the early cloud cover have kept the cu from growing tall early this aftn. These two limiting factors will continue to play into the forecast for the next 10 hrs. The capping aloft will likely keep any deep convection confined to very close to and north of the FIG-UNV-SEG line. As the wave moves to the east, it should help flare up some SHRA/TSRA over PA even if the current storms dwindle as they cross lower ONT and LE. Day1 SLGT risk remains in place for svr storms into the early nighttime. Most scenarios have the convection off to our east by 03-04Z, before midnight. Some clearing will take place, and winds go light, so some fog and/or low stratus is again possible, mainly where it would rain, and over the Laurels in the upslope of the high dewpoint air. Mins are going to stay even higher tonight than Mon AM between 60-70F. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Early morning stability will last for much of the day. The front will be kind of washed out. Not as much forcing will move overhead Tuesday as the upper ridge along the E coast amplifies a bit, and deflects the stream of short wave troughs to the north of the CWA. Expect some daytime/diurnal convection on the high ground to get tall enough to make a shower or two. But, PoPs will be lower than today without the addition of any MCVs or other short waves to help out. Temps will be summer like with 80s spreading north all the way to the NY border. A stray bank thermometer could read 90F in the cities of the SE. As odd as it seems, those numbers are "only" 8-12F above normals. Record maxes for Tuesday at MDT and IPT are 90F and 92F respectively. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Abnormal warmth will continue into midweek ahead of the aforementioned cold front getting ready to sweep through central PA. Expect numerous showers and storms along/ahead of the front Wednesday afternoon and evening as a northern stream upper trough further aids in large scale forcing for ascent. While a linear storm mode is expected given the shear vectors oriented parallel to the front, approximately 30 knots of 0-6 km shear should help a few of these linear segments to organize/grow and thus exhibit the potential for damaging wind gusts. The degree of low level instability remains an uncertainty, especially across the Alleghenies where low clouds may be plentiful early Wednesday. Clearer skies into the Susquehanna Valley look to spell temperatures climbing into the mid-upper 80s, while locales west of the Allegheny Front only warm into the mid 70s to near 80. Rain chances will continue through late week as weak southern stream cyclonic flow lingers west of ridging across the western Atlantic. Additionally, a low approaching the mid Atlantic Coast will help to keep mid level height fields above normal, with the frontal boundary returning north across PA and subsequently maintaining the mid September warm/humid airmass. Ridging does look to build in at some point this weekend, but still a tough call as to whether it will arrive quick enough on Saturday to negate rain chances. Sunday currently looks warm and dry with return flow setting up for early week and thus leading to renewed shower/storm chances and continued above normal temperatures. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... MVFR cigs at BFD and JST continue, but much more clearing/mixing/scattering is seen in the sat pics over the last hour. The frontal zone over the nrn tier is tough to pick out, but likely over or just south of BFD and IPT. A few SHRA/TSRA could flare up as far S as a FIG-UNV-SEG line. These would be the most-likely terminals to see any TSRA if they can manage to form. The risk of SHRA/TSRA reduces later this evening, prob before midnight local (04Z), as the forcing from a potent convective vortex moves to the east. Some fog may form if the air fields get wet, and some lower clouds are again possible over the Laurels (JST) due to the slow upslope flow of high dewpoint air and decoupling of the night. Less SHRA are anticipated Tues with almost no forcing seen aloft. A low pressure area crossing nrn ONT in mid week will likely push a cold front into the state on Wed, and yield perhaps the best chc of SHRA/TSRA this week. The front doesn't look like it will push all the way through the CWA, though, hanging up overhead thru the end of the week. Outlook... Tues...Isold/Sct PM SHRA and brief MVFR conditions possible north. Otherwise VFR. Wed...CFRONT arrives. SHRA/TSRA likely. Restrictions likely. Thurs-Sat...Sct PM SHRA/TSRA. Localized restrictions possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Guseman AVIATION...Dangelo/RXR/Gartner
Hazardous Weather Outlook National Weather Service State College PA 554 PM EDT Mon Sep 13 2021 PAZ005-006-011-012-037-041-042-045-046-049-051>053-058-142200- McKean-Potter-Cameron-Northern Clinton-Tioga-Northern Lycoming- Sullivan-Southern Clinton-Southern Lycoming-Union-Montour- Northumberland-Columbia-Schuylkill- 554 PM EDT Mon Sep 13 2021 ...SEVERE THUNDERSTORM WATCH 496 IN EFFECT UNTIL 1 AM EDT TUESDAY... 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...Tuesday through Sunday. Another round of potentially severe thunderstorms, containing damaging winds 60 mph or greater and large hail exceeding 1 inch in diameter are possible Wednesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ004-142200- Warren- 554 PM EDT Mon Sep 13 2021 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Another round of potentially severe thunderstorms, containing damaging winds 60 mph or greater and large hail exceeding 1 inch in diameter are possible Wednesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ010-017>019-050-142200- Elk-Clearfield-Northern Centre-Southern Centre-Snyder- 554 PM EDT Mon Sep 13 2021 ...SEVERE THUNDERSTORM WATCH 496 IN EFFECT UNTIL 1 AM EDT TUESDAY... 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...Tuesday through Sunday. Another round of potentially severe thunderstorms, containing damaging winds 60 mph or greater and large hail exceeding 1 inch in diameter are possible Wednesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ024>028-033>036-056-057-059-063>066-142200- Cambria-Blair-Huntingdon-Mifflin-Juniata-Somerset-Bedford-Fulton- Franklin-Perry-Dauphin-Lebanon-Cumberland-Adams-York-Lancaster- 554 PM EDT Mon Sep 13 2021 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...Tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Another round of potentially severe thunderstorms, containing damaging winds 60 mph or greater and large hail exceeding 1 inch in diameter are possible Wednesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement
National Weather Service State College PA
515 PM EDT Mon Sep 13 2021
PAZ004-132145-
Warren PA-
515 PM EDT Mon Sep 13 2021
...Strong thunderstorms will impact portions of Warren County through
545 PM EDT...
At 514 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Long Point State Park to near Corry to 6
miles northeast of Cambridge Springs. Movement was east at 55 mph.
HAZARD...Wind gusts of 50 to 55 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Warren, Columbus, Youngsville, Russell, Spring Creek, Scandia,
Lottsville, Grand Valley, Warren South, Garland, Chapman State Park,
Tidioute, Sugar Grove, Starbrick and Bear Lake.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in State College PA.
&&
LAT...LON 4200 7892 4189 7892 4167 7938 4172 7961
4200 7960
TIME...MOT...LOC 2114Z 277DEG 46KT 4212 7944 4197 7967 4184 7995
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH
BanghoffSpecial Weather Statement
National Weather Service State College PA
545 PM EDT Mon Sep 13 2021
PAZ006-037-132215-
Potter PA-Tioga PA-
545 PM EDT Mon Sep 13 2021
...A strong thunderstorm will impact portions of southeastern Potter
and southwestern Tioga Counties through 615 PM EDT...
At 544 PM EDT, Doppler radar was tracking a strong thunderstorm near
Cherry Springs State Park, moving east at 35 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 damage to outdoor objects is
possible.
Locations impacted include...
Galeton, Lyman Run State Park, Denton Hill State Park, Cherry Springs
State Park, Leonard Harrison State Park and Sweden Valley.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4176 7741 4154 7754 4154 7760 4167 7805
4176 7799
TIME...MOT...LOC 2144Z 280DEG 31KT 4170 7792
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
BanghoffSpecial Weather Statement
National Weather Service State College PA
614 PM EDT Mon Sep 13 2021
PAZ006-037-041-132245-
Potter PA-Northern Lycoming PA-Tioga PA-
614 PM EDT Mon Sep 13 2021
...Strong thunderstorms will impact portions of northwestern
Lycoming, southeastern Potter and southwestern Tioga Counties through
645 PM EDT...
At 614 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Ole Bull State Park to 6 miles southwest
of Cherry Springs State Park. Movement was east at 30 mph.
HAZARD...Wind gusts of 50 to 55 mph and nickel size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Ole Bull State Park, Slate Run, Leetonia, Cedar Run and Ski Sawmill
Ski Area.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in State College PA.
A Severe Thunderstorm Watch remains in effect until 100 AM EDT for
north central Pennsylvania.
&&
LAT...LON 4154 7713 4145 7759 4148 7760 4148 7776
4159 7803 4167 7768
TIME...MOT...LOC 2214Z 289DEG 25KT 4162 7767 4159 7789
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...55 MPH
BanghoffSpecial Weather Statement
National Weather Service State College PA
621 PM EDT Mon Sep 13 2021
PAZ010-132245-
Elk PA-
621 PM EDT Mon Sep 13 2021
...A strong thunderstorm will impact portions of southwestern Elk
County through 645 PM EDT...
At 621 PM EDT, Doppler radar was tracking a strong thunderstorm over
Marienville, moving east at 40 mph.
HAZARD...Wind gusts up to 50 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Ridgway, Johnsonburg, Brandy Camp, Portland Mills and Brockport.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in State College PA.
A Severe Thunderstorm Watch remains in effect until 100 AM EDT for
north central Pennsylvania.
&&
LAT...LON 4142 7909 4143 7906 4145 7906 4145 7898
4144 7896 4153 7896 4149 7860 4123 7872
4123 7874 4126 7874 4137 7897 4135 7902
4136 7904 4134 7910 4141 7910
TIME...MOT...LOC 2221Z 285DEG 33KT 4144 7909
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH
BanghoffSpecial Weather Statement
National Weather Service State College PA
636 PM EDT Mon Sep 13 2021
PAZ037-041-132300-
Northern Lycoming PA-Tioga PA-
636 PM EDT Mon Sep 13 2021
...Strong thunderstorms will impact portions of northwestern Lycoming
and south central Tioga Counties through 700 PM EDT...
At 636 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Cedar Run to Slate Run. Movement was
southeast at 35 mph.
HAZARD...Wind gusts of 50 to 55 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Ralston, Cedar Run, Slate Run, English Center, Trout Run, Buttonwood
and Ski Sawmill Ski Area.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in State College PA.
A Severe Thunderstorm Watch remains in effect until 100 AM EDT for
north central Pennsylvania.
&&
LAT...LON 4148 7679 4147 7677 4146 7677 4130 7715
4146 7760 4148 7760 4160 7738
TIME...MOT...LOC 2236Z 292DEG 31KT 4155 7737 4147 7753
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...55 MPH
BanghoffThe State College radar (KCCX), 102 km away, was scanning. The volume nearest the first event began at 23:10 UTC.
14 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires along Wallis Run Road.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto wires northeast of Montoursville.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires northwest of Hughsville.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees near Picture Rocks.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees onto wires east of Hughsville.
A severe thunderstorm producing winds estimated near 60 mph knocked down numerous trees in far southeastern Lycoming County.
A severe thunderstorm producing winds estimated near 60 mph knocked down several trees and damaged a roof in far northwestern Columbia County.
A severe thunderstorm producing winds estimated near 60 mph knocked down multiple trees, including some on homes, in Orangeville.
A severe thunderstorm producing winds estimated near 60 mph knocked down a tree onto a home in Berwick.
A severe thunderstorm producing winds estimated near 60 mph knocked down trees and wires in the Mifflinville area.
A severe thunderstorm producing winds estimated near 80 mph uprooted numerous trees near Mountain Grove.
A severe thunderstorm producing winds estimated near 60 mph knocked down two large trees south of Nuremburg.
A severe thunderstorm producing winds estimated near 70 mph knocked down numerous trees and produced widespread crop damage northwest of Hometown.
A severe thunderstorm produced a 68 mph wind gust measured by a PennDOT station at the Delano exit on I-81.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2021Every state in 2021This day in weather historyWarnings in Pennsylvania, September 2021
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: 984708, 984714, 984713, 984715, 984716, 984717, 984718, 984720, 984719, 984721, 984741, 984747, 984746, 984748.