F1 tornado, Mercer to Raymilton, Pennsylvania, April 28, 2002

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 mphthis tornado

   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 mph

   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.

Rating

F1

Date

April 28, 2002

Touchdown

2:45 PM EDT (18:45 UTC)

Path length

16.0 miles (25.7 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

Property damage

$1.0 million

Counties

Mercer and Venango counties

Touchdown point

41.280, -80.170

Lift-off point

41.380, -79.880

Record number

521

A storm producing two separate tornadoes moved across Mercer and Venango counties. The first tornado spawned by this storm, an F0, touched down in Mercer County at 1:35 PM EST near the community of Hermitage (approximately 2 miles east of Sharon) and moved to the east-northeast for about 6 miles before dissipating at approximately 1:40 PM EST. The maximum estimated winds were about 70 MPH. Some of the damage observed from this first tornado included a downed fire tower near Hermitage. The windward side of a barn in Jefferson Township was blown apart and the adjacent building exhibited large holes in the metal sides from flying debris. A garage that was under construction also suffered major damage. Numerous trees and telephone poles were either toppled or snapped along the path of the tornado. There were also some trees toppled onto houses. The same storm continued moving to the east-northeast and produced another tornado in Mercer County, an F1, which touched down about 5 miles northeast of Mercer near Lake Latonka at 1:45 PM EST. It moved to the east-northeast along Routes 65 and 965, eventually crossing over into Venango County at 2:00 PM EST approximately 5 miles east of the town of Stoneboro. The tornado continued traveling to the east-northeast in Venango County, passing just south of the town of Polk, then dissipating about 2 miles southwest of Franklin at approximately 2:06 PM EST. Even though the tornado dissipated, sporadic downburst wind damage continued for several more miles in Venango County. The total path length of this tornado was about 16 miles, with 10 of those miles in Mercer County and 6 miles in Venango County. The maximum estimated winds were 105 MPH with a maximum width of about 200 yards. In Mercer County, this tornado produced structural damage to several houses at Lake Latonka. Also, there were several decks and porches destroyed. Some sheds and small garages were damaged, and there were numerous trees toppled or snapped. One boat was blown over, and siding and shingles were blown off houses. Near Jackson Corners, there were numerous large trees downed, as well as power lines and telephone poles. Also, several trees were toppled onto houses. Several signs were destroyed, and roofs, siding and shingles were ripped from several houses and out-buildings. The fish hatchery building had about a 100-square foot piece of its metal roof ripped off and thrown several hundred yards. A relatively new garage was completely destroyed. Also, a wooden 2x4 board was found thrown into a mobile home and pieces of wood were also driven into the front of a car. As the tornado approached the Venango County line, the damage pattern widened considerably. Thousands of trees and branches were snapped or toppled. At this point the path width of damage stretched to nearly nearly one-half mile, as the tornado track was joined by microburst damage.In Venango County, this tornado caused minor damage to 3 homes; moderate damage to another, and totally destroyed 4 barns. There were also 2 tree farms that suffered major damage and one-half of a double-wide mobile home was turned completely over onto its roof.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

2 minutes of warning. NWS PBZ issued a tornado warning for this county at 18:43 UTC, 2 minutes before the tornado touched down, in force until 19:30 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Moderate Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 16:56 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

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.

Franklin(Awos) (FKL), 15 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Pittsburgh radar (KPBZ), 90 km away, was scanning. The volume nearest the touchdown began at 18:45 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.

The live radar over the trackEvery 2002 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

37 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.