F1 tornado, Norristown, Pennsylvania, August 14, 1994

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

August 14, 1994

Touchdown

2:10 PM EDT (18:10 UTC)

Path length

1.0 miles (1.6 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

County

Montgomery County

Touchdown point

40.080, -75.380

Record number

878

,,,,,,,,Lightning A F1 (Fujita Scale) tornado touched down in the Brandywine Village/Lafayette Park area of Upper Merion Township on Allendale Road just to the north of the Pennsylvania Turnpike (Interstate 276). The tornado sighting was phoned into the National Weather Service by a SKYWARN Spotter. The tornado stayed on the ground for about one mile before lifting around Crossfield Road. Most of the wind damage was downed or snapped (40 to 50) trees. The bulk of the uprooted trees were either in poor health or very old. Two houses were damaged by trees falling on them. The worse one sustained about $6,000 in damage to its roof, porch, upstairs bathroom and gutters. The tornado touched down within one mile of the King of Prussia Mall. No injuries were reported. This was the 12th confirmed tornado in the Greater Philadelphia Metropolitan Area this year. Elsewhere in Montgomery County damaging winds knocked over a centerfield fence and uprooted between 12 and 18 trees in Upper Gwynedd Township. A lightning strike ignited a fire in an Upper Gwynedd house. It apparently entered through the electrical box and started a fire in the basement. Damage was estimated between $25,000 and $30,000. Thunderstorm winds uprooted a large pear tree in Audubon. Frequent lightning resulted in power outages to 55,000 Philadelphia Electric Company (PECO) customers throughout their service area.

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 Moderate Risk. The outlook in force was issued at 06:00 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.

Willow Grove Nas (NXX), 24 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 1994 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

3 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.