EF1 tornado, Big Spg to North Four Corners, Kentucky, May 21, 2010

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 21, 2010

Touchdown

7:28 PM CDT (00:28 UTC)

Lifted

7:30 PM CDT (00:30 UTC)

On the ground

2 minutes

Path length

1.8 miles (2.8 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$35,000

Counties

Hardin and Breckinridge counties

Touchdown point

37.803, -86.171

Lift-off point

37.790, -86.144

Record number

1005211828-01

A cold front from an occluded low over the Great Lakes was swinging southward toward central Kentucky during the afternoon hours of May 21. A shortwave progressing across the region helped to spawn strong thunderstorms. With ample shear one of these storms was able to produce a tornado that touched down multiple times across Breckinridge and Hardin counties.

An NWS storm survey and interviews with residents confirmed a tornado touched down at approximately 828 PM EDT just west of Big Springs. A large barn suffered significant roof and wall damage resulting in the tornado to be rated EF-1 here with 85-90 mph winds. Additional damage to hardwood trees was noted along Highway 333 south. The tornado appeared to be skipping along the path at this time. The tornado lifted above the community of Big Springs, then touched down again along High Plains Road before lifting again. It then touched down again along Rineyville-Big Springs road in Harding county where it damaged a double wide mobile home. The damage at this location was consistent with EF-0 tornado damage with winds of 80-85 mph.

An NWS storm survey and interviews with residents confirmed a tornado touched down at approximately 828 PM EDT just west of Big Springs. A large barn suffered significant roof and wall damage resulting in the tornado to be rated EF-1 here with 85-90 mph winds. Additional damage to hardwood trees was noted along Highway 333 south. The tornado appeared to be skipping along the path at this time. The tornado lifted above the community of Big Springs, then touched down again along High Plains Road before lifting again. It then touched down again along Rineyville-Big Springs road in Harding county where it damaged a double wide mobile home. The damage at this location was consistent with EF-0 tornado damage with winds of 80-85 mph.

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

0 minutes of warning. NWS LMK issued a tornado warning for this county at 00:28 UTC, 0 minutes before the tornado touched down, in force until 00:44 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 General Thunderstorms Risk. The outlook in force was issued at 19:53 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.

Fort Knox/Godman (FTK), 20 km from the path, in the two hours either side.

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

The Louisville radar (KLVX), 27 km away, was scanning. The volume nearest the touchdown began at 00:30 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 2010 tornado in KentuckyEvery tornado in Kentucky since 1950Warnings in force in Kentucky nowThe forecast where you are

5 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.