F1 tornado, Willow Street, Pennsylvania, July 27, 2004

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

July 27, 2004

Touchdown

7:15 PM EDT (23:15 UTC)

Path length

4.0 miles (6.4 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Property damage

$100,000

County

Lancaster County

Touchdown point

39.980, -76.280

Lift-off point

39.980, -76.280

Record number

344

A thunderstorm spawned an F1 tornado in Lancaster County during the evening of July 27th. The tornado first touched down at 18:15 EST on an amish farm near the intersection of Byerland Church Road and Route 272 just south of the town of Willow Street. The tornado traveled east-southeast for 4 miles, crossing route 222 and dissipating south of the town of Refton at 18:20 EST.The width of the tornado damage was about 100 yards, but the strong F1 damage was limited to a path about 30 yards wide. The tornado damaged 4 or 5 homes, including partially removing the roof of one farm house. Several barns and silos were also damaged. Hundreds of trees were knocked down, and strong rotation could be seen in corn fields which the tornado crossed.The most significant damage occurred at a trucking company just east of route 272. Two tractor trailers were lifted into the air by the tornado. Security video at the trucking company captured the tornado as it moved through the truck yard. Top winds were estimated at 110 mph, putting this into the strong F1 tornado category. There were no injuries or deaths.

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

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

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 General Thunderstorms Risk. The outlook in force was issued at 20:00 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.

The live radar over the trackEvery 2004 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

1 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.