EF1 tornado, Lewistown, Pennsylvania, May 23, 2011

1. EF065 to 85 mph

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

2. EF186 to 110 mphthis tornado

   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

EF1

Date

May 23, 2011

Touchdown

6:37 PM EDT (22:37 UTC)

Lifted

6:38 PM EDT (22:38 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

$20,000

County

Schuylkill County

Touchdown point

40.737, -76.050

Lift-off point

40.738, -76.046

Record number

1105231637-01

An upper level disturbance moved out of the Ohio Valley and triggered severe thunderstorms and tornadoes across portions of central and eastern Pennsylvania. A total of 3 tornadoes were confirmed ranging in magnitude from EF1-EF2.

A NWS storm survey team found evidence that a small EF1 tornado touched down just south of Brockton in Walker Township at 1837 EDT. The tornado traveled only about a quarter of a mile to the east-northeast, before dissipating near Kettle Road around 1838 EDT. The tornado was embedded in a larger area of downburst winds, which extended approximately two miles farther to the east, crossing Catawissa Road.||Damage caused by the tornado was mainly confined to a wooded area, snapping or toppling about 25 trees. The tornado appeared to dissipate on the property along Kettle Road. Here, a large awning/roof was removed from a home. A barn was completely leveled. Across Kettle Road, another home lost portions of it's roof from the wind. Moderate damage to the house was also sustained from flying debris from the collapsed barn across the road. The downburst winds next encountered a home and several barns along Catawissa Road over a mile to the east. Significant roofing loss was noted at two barns on the west side of Catawissa Road, and one on the east side of Catawissa Road. This marked the end of the concentrated downburst damage path.||The tornado and downburst winds both had damage indicators implying peak winds around 95 mph. The tornado was rated an EF1. There were no injuries or fatalities.

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.

The county was under a severe thunderstorm watch, issued at 14:48 UTC and running to 00:00 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 19:39 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 Binghamton radar (KBGM), 163 km away, was scanning. The volume nearest the touchdown began at 22:36 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 2011 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

17 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.