Tornadoes · United States · Pennsylvania · 2025
EF0 tornado, Mechanics Grove, Pennsylvania, September 4, 2025
This EF0 tornado ran 0.1 miles across Lancaster County on September 4, 2025, touching down at 9:31 PM EDT and reaching 30 yards wide. It killed nobody, and did $10,000 of property damage.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.
The record
- Rating
- EF0
- Date
- September 4, 2025
- Touchdown
- 9:31 PM EDT (01:31 UTC)
- Lifted
- 9:32 PM EDT (01:32 UTC)
- On the ground
- 1 minutes
- Path length
- 0.1 miles (0.2 km)
- Path width
- 30 yards (27 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $10,000
- County
- Lancaster County
- Touchdown point
- 39.873, -76.124
- Lift-off point
- 39.874, -76.121
- Record number
- 2509041931-01
The damage survey
2 damage points were recorded along this path by NWS CTP, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 70 mph.
- Dugout roof lifted up and concrete block wall partially knocked over (likely because dugout was open in the direction the wind was coming from and lifted the roof).
- Corn crop damage - laying down toward the center of the circulation.
Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.
What the Weather Service recorded
A surface cold front stationed across west-central Pennsylvania produced scattered thunderstorms into central and eastern Pennsylvania during the afternoon and evening hours of September 4, 2025. Thunderstorms remained strong-to-severe across north-central Pennsylvania, producing isolated wind damage. Shear in the lowest levels allowed for a brief, weak tornado to form in Lancaster County.
An EF-0 tornado with an estimated peak wind of 70 mph occurred southeast of Collins, PA on the evening of Thursday, September 4, 2025. It lifted the roof off of a dugout at the Solanco Youth Baseball Association and then continued across Kirkwood Pike, where it caused minor crop damage.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
What forecasters said that day
The local office's own words before the tornado touched down, 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 tornado touched down at Sep 4, 5:02 PM EDT, 4 hours 29 minutes earlier.
Area forecast discussion, Sep 4, 5:02 PM EDT, 4 hours 29 minutes before
Area Forecast Discussion National Weather Service State College PA 502 PM EDT Thu Sep 4 2025 .SYNOPSIS... * A series of cold fronts will bring a risk for strong thunderstorms Thursday and again Saturday. * Two rounds of storms are expected today, one ahead of the cold front and the second along the front as it pushes southeast. * Temperatures trend below normal again next week with high pressure and dry weather prevailing. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Under a prevailing upper trough, a mid-level vorticity maximum will rotate through the Mid Atlantic today accompanied by a surface cold front. Morning radar and satellite imagery shows weak convection moving across western Pennsylvania ahead of the main cold front currently draped over the southern Great Lakes region and into central Ohio. As the front moves east, these showers and storm should re- intensify as they encounter sufficient moisture with dewpoints in the upper 50s to low 60s, marginal instability (up to 750 J/kg), and ample shear (30 - 40kts). Convection allowing models depict potential for two distinct rounds of showers/storms. The first would be associated with the aforementioned line of storms that will advance into southeast PA by later afternoon and evening. The second would be along the surface cold front, which likely struggles to get past the I-99/I-80 corridor by Thursday evening. The SPC has issued a Marginal Risk for nearly all of Pennsylvania. The best shear will be across northern PA into New York, while the best instability will be well south of the region (Southern Appalachians). Pennsylvania will have sufficient amounts of instability and shear to support a marginal threat of damaging winds. Highs today will range from the mid 60s in northwest PA where more clouds/precipitation will keep temperatures at bay, to the mid 80s in southeast PA where most of the day should remain sunny or at least partly cloudy before convection arrives. Tonight, lower dewpoints will filter into northwest PA behind the cold front allowing temperatures to drop into the mid 40s. Farther southeast, more clouds/lingering showers will keep temperatures much more mild in the upper 50s to lower 60s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... On Friday, high pressure will briefly regain control of the region giving way to mostly sunny skies, dry conditions, and another seasonably mild day. Friday morning will be relatively mild with patchy valley fog likely over most of the CWA. It is worth noting that Thursday's cold front will get hung up across the Central Mountains, it will still be rather humid on Friday afternoon in southeast PA. Given that the front is expected to stall out highs on Friday will be slightly warmer than Thursday with parts of the southeast reaching to mid 80s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... For the long term period, a prevailing upper trough across the eastern US will remain in place, perhaps lifting a bit by the middle of next week. By Saturday, a stronger cold front (compared to Thursday) will sweep through the Commonwealth and bring a renewed chance for showers and thunderstorms. There remains some uncertainty regarding how much instability will be in place ahead of the front, but scattered strong to severe thunderstorms seem like a good bet. As is typical with these systems, the best chance for severe will likely be in southeast PA and an SPC Marginal Risk is probable for Saturday. After the cold front sweeps through, another fall-like pattern will settle in for the second half of the weekend and into next week. The airmass moving overhead will be the coolest of the season so far. Highs in the 60s and 70s will pair with lows in the 30s to 50s. Frost or freeze conditions seem like a good bet for the typical cool spots in northwest PA early next week along with river valley fog. Abundant sunshine and dry conditions are favored, with increasing moisture and chances for rain toward the middle to end of the week. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... 21Z/5pm EDT Update: A quick 21Z/5pm EDT update to the TAF package has been issued for all terminals. This update has deviated slightly from the 18Z TAF package due to current radar trends which will allow for extended windows of relatively dry conditions over the next hours for the bulk of central Pennsylvania's airfields. The next batch of precipitation associated with the surface cold front stationed east of BFD will continue tracking east and impact JST/AOO closer to the 22-23Z timeframe and gradually overspread the area. The most recent suite of hi-res model guidance does indicate some decay of precipitation closer to MDT/LNS so have trimmed back mentions of precipitation this evening at MDT; however, SHRA/TSRA from MD is expected to make a run at LNS for a two- hour period near sunset. Given the precipitation expected and that has already hit the ground, have decided to increase low-level cloud mentions across much of the area outside of AOO where precipitation chances are slightly lower over the next couple of hours. Low confidence at MDT/LNS as GLAMP model guidance deviates from RAP/HREF model guidance with respect to low clouds overnight with higher confidence at JST/BFD/UNV/IPT overnight. Clearing will be relatively quick with southwesterly flow; however, IPT will likely hold onto lower ceilings/visibilities through ~14Z Friday. Clearing skies are projected by the bulk of model guidance allowing for widespread VFR conditions through 18Z Fri. Outlook... Sat...Chance of SHRA w/ TSRA possible, especially SE. Sun-Mon...Clearing with VFR conditions. Breezy. Tue-Wed...Clear. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...Banghoff/Bowen NEAR TERM...Bowen SHORT TERM...Bowen LONG TERM...Banghoff/Bowen AVIATION...NPB
Hazardous weather outlook, Sep 4, 1:37 PM EDT, 7 hours 54 minutes before
Hazardous Weather Outlook National Weather Service State College PA 137 PM EDT Thu Sep 4 2025 PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053- 056>059-063>066-051745- Warren-McKean-Potter-Elk-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- 137 PM EDT Thu Sep 4 2025 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. Strong to severe thunderstorms with damaging winds are possible today. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather.
In the hours before
Special weather statement, Sep 4, 3:43 PM EDT, 5 hours 48 minutes before
Special Weather Statement National Weather Service State College PA 343 PM EDT Thu Sep 4 2025 PAZ065-066-042345- York-Lancaster- 343 PM EDT Thu Sep 4 2025 ...STRONG THUNDERSTORMS EXPECTED... Strong thunderstorms are expected to move through York and Lancaster Counties through 5 PM EDT. These storms will have the potential to make wind gusts near 55 MPH. A few of the storms could intensify, and make damaging wind gusts or large hail. Be certain to monitor local radio stations and available media sources for additional information and possible warnings from your National Weather Service.
Local storm report, Sep 4, 7:55 PM EDT, 1 hour 36 minutes before
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</html>The air that afternoon
The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.
Washington/Dulle, VA (KIAD), 00:00Z
1.5 hours before the tornado, 150 km from the path. September 5, 2025.
- Mixed-layer CAPE
- 829 J/kg
- Mixed-layer CIN
- -7 J/kg
- Surface CAPE
- 1777 J/kg
- Mixed-layer LCL
- 1281 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 113 m²/s²
- 0-3 km storm-relative helicity
- 157 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 4.3
- 0-3 km lapse rate
- 7.7 K/km
The surface observations
Coatesville (MQS), 25 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Dover AFB radar (KDOX), 130 km away, was scanning. The volume nearest the touchdown began at 01:33 UTC.
Open the radar archive at this moment, over the track
Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.
This ground now
The live radar over the trackEvery 2025 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are
The other tornadoes of September 4, 2025
4 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| September 4 | 4:51 PM EDT | EF1 | Halifax, VA | 0.3 | 225 | $75,000 | ||
| September 4 | 5:57 PM EDT | EF0 | Oneida, NY | 3.0 | 100 | $13,000 | ||
| September 4 | 6:29 PM CDT | EF0 | Nicollet, MN | 3.5 | 40 | $5,000 | ||
| September 4 | 6:45 PM CDT | EF0 | Nicollet, MN | 1.0 | 40 |
What this means
Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.