Tornadoes · United States · Pennsylvania · 1985

F4 tornado, Venango and Forest counties, Pennsylvania, May 31, 1985

This F4 tornado ran 29.0 miles across Venango and Forest counties on May 31, 1985, touching down at 6:30 PM EDT and reaching 800 yards wide. It killed 7 people and injured 30.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 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.

  4. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mphthis tornado

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 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.

  7. 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
F4
Date
May 31, 1985
Touchdown
6:30 PM EDT (22:30 UTC)
Path length
29.0 miles (46.7 km)
Path width
800 yards (732 m)
Deaths
7
Injuries
30
Counties
Venango and Forest counties
Touchdown point
41.550, -79.620
Lift-off point
41.450, -78.930
Record number
344

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.

Pittsburgh, PA (KPIT), 12:00Z

10.5 hours before the tornado, 140 km from the path. May 31, 1985.

Skew-T log-pSkew-T log-p diagram, Pittsburgh, PA at 12:00Z on 1985-05-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -7219, lifted condensation level 642 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Pittsburgh, PA at 12:00Z on 1985-05-31The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 341 square meters per square second, 0 to 6 km bulk shear 51 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-7219 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
642 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
341 m²/s²
0-3 km storm-relative helicity
519 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7
0-3 km lapse rate
4.3 K/km

Open this sounding in Storm Lab

Pittsburgh, PA (KPIT), 00:00Z

1.5 hours after it, 140 km from the path. June 1, 1985.

Skew-T log-pSkew-T log-p diagram, Pittsburgh, PA at 00:00Z on 1985-06-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN 0, lifted condensation level NaN meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Pittsburgh, PA at 00:00Z on 1985-06-01The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 215 square meters per square second, 0 to 6 km bulk shear 50 knots.19395878Sfc1 km3 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
0 J/kg
Surface CAPE
602 J/kg
Mixed-layer LCL
NaN m above ground
0-6 km bulk shear
50 kt
0-1 km bulk shear
27 kt
0-1 km storm-relative helicity
215 m²/s²
0-3 km storm-relative helicity
277 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.4
0-3 km lapse rate
7.0 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1985 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

The other tornadoes of May 31, 1985

29 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 313:59 PM CDTF4Ashtabula, OH to PA14.04001282$5 million to $50 million
May 315:05 PM EDTF3Trumbull, OH15.044030$500,000 to $5 million
May 315:10 PM EDTF2Crawford, PA4.02001
May 314:17 PM CDTF4Trumbull, OH to PA56.235016125$5 million to $50 million
May 315:23 PM EDTF3Crawford, PA23.02772
May 314:25 PM CDTF4Erie, PA to NY28.0440
May 314:28 PM CDTF2Ashtabula, OH to PA10.022015$500,000 to $5 million
May 316:12 PM EDTF3Crawford, PA8.0427$500,000 to $5 million
May 316:25 PM EDTF3Chautauqua, NY13.017710$500,000 to $5 million
May 315:30 PM CDTF5Portage, OH to PA47.045018310$50 million to $500 million
May 316:30 PM EDTF1Warren, PA5.0130
May 316:50 PM EDTF2Forest, PA19.0300
May 317:06 PM EDTF1Madison, OH0.550$50,000 to $500,000
May 317:15 PM EDTF3Licking, OH29.0150120$5 million to $50 million
May 317:30 PM EDTF3Warren, PA17.08008
May 317:35 PM EDTF4Clearfield, PA69.03,330$5 million to $50 million
May 317:35 PM EDTF2Columbiana, OH15.022020$5 million to $50 million
May 317:50 PM EDTF1Muskingum, OH11.0775$500,000 to $5 million
May 317:54 PM EDTF2Venango, PA6.01501
May 317:56 PM EDTF0Venango, PA5.0300
May 318:00 PM EDTF4Warren, PA29.01,000440
May 318:10 PM EDTF3Beaver, PA39.02439120$5 million to $50 million
May 318:45 PM EDTF1Stark, OH0.250$5,000 to $50,000
May 319:05 PM EDTF1Adams, OH2.077$5,000 to $50,000
May 319:25 PM EDTF3Lycoming, PA19.0910660$5 million to $50 million
May 319:53 PM EDTF0Indiana, PA6.027
May 3110:30 PM EDTF1St. Lawrence, NY5.050$50,000 to $500,000
May 3110:45 PM EDTF1Luzerne, PA11.0530$50,000 to $500,000
May 3112:05 AM EDTF1Monroe, PA0.217$500 to $5,000

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.