EF0 tornado, Ralphton, Pennsylvania, August 7, 2013

1. EF065 to 85 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 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. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 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

EF0

Date

August 7, 2013

Touchdown

7:20 PM EDT (23:20 UTC)

Lifted

7:21 PM EDT (23:21 UTC)

On the ground

1 minutes

Path length

0.2 miles (0.4 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$2,000

County

Somerset County

Touchdown point

40.110, -79.007

Lift-off point

40.113, -79.005

Record number

1308071720-01

Severe thunderstorm clusters across western Pennsylvania organized into bowing line segments as they moved east-southeast across the southern Alleghenies and Laurel Highlands during the late afternoon and early evening. The line of storms produced isolated wind damage and sub-severe hail. A more discrete thunderstorm cell just ahead of the main line of storms produced a brief, weak EF0 tornado in Somerset County. An area of locally heavy rain produced flash flooding in York County during the late evening, with areal flooding persisting into the early morning on 8/8.

A storm survey conducted in Quemahoning Township in Somerset County confirmed a brief, weak EF0 tornado occurred a few miles east of Ralphton near Horner Church Road. One home sustained minor damage and one barn roof was partially torn off. Over 2 dozen trees were knocked down or damaged. The estimated maximum wind speed was between 70-80 mph. The maximum path width was 75 yards with a path length of about 0.25 mile. There were no injuries or fatalities.

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

7 minutes of warning. NWS CTP issued a tornado warning for this county at 23:13 UTC, 7 minutes before the tornado touched down, in force until 00:00 UTC.

The county was under a severe thunderstorm watch, issued at 19:53 UTC and running to 01:49 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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:57 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 Pittsburgh radar (KPBZ), 113 km away, was scanning. The volume nearest the touchdown began at 23:22 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.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2013 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.