F1 tornado, Narberth, Pennsylvania, September 23, 2003

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

September 23, 2003

Touchdown

7:20 AM EDT (11:20 UTC)

Path length

0.8 miles (1.3 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Property damage

$1.0 million

County

Montgomery County

Touchdown point

40.020, -75.270

Lift-off point

40.020, -75.270

Record number

647

An F1 tornado touched down along the Lower Merion Township side of the Narberth Borough/Lower Merion Township line. The tornado then proceeded east into Narberth Borough and remained on the ground for three-quarters of a mile. Wind damage was mainly whole trees and wires that were knocked down. More than 100 whole trees were knocked down. Dozens of homes were damaged by fallen trees. One tree fell through one house in Narbrook Park. The parent thunderstorm produced straight line wind damage in Delaware County and southwestern parts of Lower Merion Township before the tornado formed near North Wynnewood Avenue. The tornado proceeded into Narberth Borough along Windsor Avenue before lifting. A state of emergency was declared in Lower Merion Township as five major roads were closed including most of County Line Road. Downed wires temporarily children in a school bus. They were not injured. A tree fell on the SEPTA Regional Rail R5 train as it was leaving the Wynnewood Station. The unharmed passengers were removed from the train. Service was suspended for several hours. The path length of the tornado was about three-quarters of a mile and its path width was about 100 yards. The maximum estimated wind speed was 75 mph. The preliminary property damage estimate was one million dollars. A few thousand home and businesses lost power. All power was restored by the afternoon of the 24th.

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 05:16 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 Philadelphia radar (KDIX), 74 km away, was scanning. The volume nearest the touchdown began at 11:18 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 2003 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

10 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.