EF1 tornado, Summertown, Tennessee, April 27, 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

April 27, 2011

Touchdown

5:50 AM CDT (10:50 UTC)

Lifted

5:55 AM CDT (10:55 UTC)

On the ground

5 minutes

Path length

2.7 miles (4.3 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

1

Property damage

$11,000

Crop damage

$75,000

County

Lawrence County

Touchdown point

35.412, -87.321

Lift-off point

35.431, -87.280

Record number

1104270450-02

During the early morning hours on Wednesday, April 27th, twelve tornadoes occurred across Middle Tennessee. Seven of these were EF0 tornadoes and five of these were EF1 tornadoes. Numerous thunderstorm wind damage events, along with several flash flooding events, occurred across the mid state also. This severe weather outbreak was the result of a very unstable airmass across Middle Tennessee ahead of a strong frontal system, with a warm front positioned near the Tennessee/Alabama border. As this frontal system pushed across the area through the remainder of the morning through the early evening hours, several thunderstorm wind and flash flood events also occurred as additional severe thunderstorms developed.

The tornado first touched down near the intersection of Gresham and Moore Roads and lifted near the intersections of State Highways 240 and U.S. Highway 43. Hundreds of trees were snapped and several building suffered damage. A man suffered minor injuries when part of his home on Gresham Road collapsed.

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 tornado watch, issued at 10:10 UTC and running to 12:23 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 High Risk, with a 0.30 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 06:10 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.

Columbia (MRC), 18 km from the path, in the two hours either side.

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

The Nashville radar (KOHX), 113 km away, was scanning. The volume nearest the touchdown began at 10:47 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 TennesseeEvery tornado in Tennessee since 1950Warnings in force in Tennessee nowThe forecast where you are

209 more were confirmed in the United States that day.

All 210 of them

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.