F1 tornado, Daleville to West Chester, Pennsylvania, May 31, 1998

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

May 31, 1998

Touchdown

12:52 AM EDT (04:52 UTC)

Path length

3.0 miles (4.8 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Property damage

$300,000

County

Chester County

Touchdown point

39.900, -75.630

Lift-off point

39.900, -75.620

Record number

1192

A line of severe thunderstorms pounded the southern half of Chester County mainly to the south of U.S. Route 30 (Lincoln Highway) the night of May 31st with wind gusts to near hurricane force and two tornadoes. A weak tornado (F1 on the Fujita Scale) moved through Londonderry and West Marlborough Townships. A second tornado (F1 on the Fujita Scale also) moved through eastern Pocopson and Birmingham Townships. Damage estimates were around one million dollars and included road clearance, clearing trees from houses and automobiles as well as damage to homes. Throughout the county one mobile home was destroyed, five homes had major damage or were destroyed, 19 homes had minor to moderate damage and 24 homes had minor or less damage. The hardest hit communities included Birmingham Township, Cochranville (part of West Fallowfield Township), Highland Township, Kenneth (including Kenneth Square) Township, Londonderry Township and New Garden Township. Only two persons were injured in Cochranville. Cochranville, Highland Township, Londonderry Township, Lower Oxford Township, West Fallowfield Township and West Marlborough Township all were declared either local disaster or county emergency areas. Governor Tom Ridge also declared Chester County a disaster emergency. About 115,000 homes and businesses lost power. About 28,000 customers were still without power during the night of June 1st. Power was not completely restored until the evening of the 4th. This was the fourth worst and the greatest non-winter storm to affect the PECO Energy service area in its 50 year history. About 336,000 customers lost power throughout their service area and PECO Energy distributed about 365,000 pounds of dry ice. Sections of major roads such as U.S. Route 1, and Pennsylvania State Routes 41, 52, 82 and 926 were closed by downed trees and wires. Even in open sections, traffic crawled due to non working traffic lights. Roads were still closed in Birmingham, East Fallowfield, Highland, London Grove, Londonderry and New Garden Townships the night of June 1st. Five southern Chester County School districts had to cancel classes on Monday, June 1st. One could not reopen until Wednesday, June 3rd. The line of severe thunderstorms entered the county in West Fallowfield and Lower Oxford Townships about 1240 a.m. EDT on June 1st and wasted no time causing damage. In Lower Oxford Township poles along Pennsylvania State Route 10 were snapped and Pennsylvania State Route 896 was partially blocked by downed trees. In West Fallowfield Township, the thunderstorms hit the King Road area of Cochranville the hardest. About 30 homes were damaged. A couple of mobile homes were either crushed or severely damaged by fallen trees. One woman was temporarily trapped. Several barns or silos were also destroyed. On one plot over 100 trees were uprooted. The Red Cross worked with thirteen displaced families in the area. The first tornado of the night touched down in Londonderry Township at about 12:43 a.m. EDT on June 1st. The touchdown occurred just north of the intersection of Fernwood and Jackson Roads. The tornado moved west to east into West Marlborough Township. It was there it reached its maximum intensity. The tornado continued to travel almost due east and lifted in the extreme eastern part of the township near Pennsylvania State Route 842. Hundreds of trees were knocked down, but structural damage since this tornado passed through relatively rural areas was minimal. The tornado stayed on the ground for about 6 miles and its width was about 100 yards. Even though the tornado lifted, wind damage continued farther east into East Marlborough Township. Hundreds of trees were uprooted, at least one vehicle was crushed and a flag pole was bent to the ground. In northern parts of London Grove Township, a couple of mobile homes were overturned and a tree crushed a garage. At one point during the night, all major roads were closed in New Garden Township due to downed trees and wires. As the line headed farther east, almost all of Kenneth Square lost power as large trees were uprooted. Many homes and vehicles were hit by trees. Included in the tree casualties, was a 140-year-old Kentucky Coffee Tree, which was one of the oldest in the eastern part of Pennsylvania. As the line went farther east, it dropped the second tornado of the night. At about 12:52 a.m. EDT a tornado touched down in the far eastern part of Pocopson Township along Pennsylvania State Route 52 just to the west of the Brandywine River and the intersections of Pennsylvania State Routes 52 and 100. The tornado moved northwest to southeast into Birmingham Township and intensified into a F1 tornado and caused damage. The tornado lifted just west of the Dilworthtown Inn in Dilworthtown near the Delaware County line. Hundreds of trees were down with power lines down in over one hundred locations. At least five homes had roof and window damage. The Spring Meadows Development had some of the worst damage with a couple of homes and several vehicles struck by fallen trees. The tornado was on the ground for about 3 miles and its width was about 100 yards. It appears as though the winds in this tornado reached near the high end of the F1 scale and probably were close to 100 mph at its maximum intensity.The wind damage was not done in Chester County. The line of severe thunderstorms sheared off part of the side of a house in West Chester. In Easttown, eight roads were closed because of downed trees. While most of the wind damage was in the southern half of the county, a thunderstorm in the far northern part of the county also turned severe in East and South Coventry Townships. In Bucktown in South Coventry Township, one tree fell on a home and damaged some of its shingles and rain spouts. In East Coventry Township, six roads were at least partially blocked by downed trees.

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. One was issued for the county at another hour that day.

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 Slight Risk. The outlook in force was issued at 10:32 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.

Wilmington Airport (ILG), 25 km from the path, in the two hours either side.

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

The live radar over the trackEvery 1998 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

45 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.