EF3 tornado, Greystone to Mayday, 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 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 mphthis tornado

   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

EF3

Date

April 27, 2011

Touchdown

12:40 AM EDT (04:40 UTC)

Lifted

12:56 AM EDT (04:56 UTC)

On the ground

16 minutes

Path length

13.6 miles (21.9 km)

Path width

1,000 yards (914 m)

Deaths

2

Injuries

70

Property damage

$8.0 million

Counties

Greene and Washington counties

Touchdown point

36.106, -82.702

Lift-off point

36.205, -82.491

Record number

1104272240-01

Favorable atmospheric conditions resulted in a deadly tornado outbreak across east Tennessee on the 27th. The thunderstorms produced more than 50 tornadoes across the east Tennessee area with 32 deaths and more than 200 injured. The tornadoes produced from light to heavy damage to hundreds of homes and businesses. Hail as large as baseballs was also reported.

Horse Creek Tornado. A NWS storm survey reported an EF3 tornado touched down in Greene County in the Horse Creek area, near the path where the Camp Creek tornado had passed about 1 hour and 40 minutes before. The tornado continued northeast into Washington county. It had a total path length of about 14 miles and a path width of 1000 yards. The maximum wind of 160 mph downed trees and also damaged and destroyed many houses and trailers. Multiple barns were destroyed. Two people died in the tornado...one in Greene County and one in Washington County. The fatalities were a 63 year old women (Greene County) and a 47 year old man (Washington County), both dying in their homes. The death in Greene County occurred on Morgan Branch Road. Approximate damage was 15 houses destroyed with 40 damaged; 10 mobile homes destroyed, and around 25 farms with structures destroyed.||In total, between the Camp Creek and Horse Creek tornadoes in Greene County there were 7 deaths, 293 injuries with 10 admitted to hospitals; 54 houses destroyed with 156 damaged; 46 mobile homes destroyed and 78 damaged, one public building destroyed, and structures on 88 farms destroyed with 109 damaged.

Horse Creek Tornado. A NWS storm survey reported an EF3 tornado that initially touched in the Horse Creek area in Greene county, continued a northeast path into Washington county. The tornado had weakened to an EF2 by the time it was in Washington County with 115 mph winds, but still caused extensive damage. One 47-year-old man was killed in his home.||This tornado had a total path length in the two counties of 13.6 miles.

The deaths

2 direct deaths are recorded for this tornado, each with what Storm Data knows of it.

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

0 minutes of warning. NWS MRX issued a tornado warning for this county at 04:40 UTC, 0 minutes before the tornado touched down, in force until 04:53 UTC.

The county was under a tornado watch, issued at 20:36 UTC and running to 04:51 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 Moderate Risk, with a 0.15 chance of a tornado within 25 miles. The outlook in force was issued at 00:50 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 Knoxville radar (KMRX), 72 km away, was scanning. The volume nearest the touchdown began at 04:37 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.