EF0 tornado, (Anw)Ainsworth Muni to Johnstown, Nebraska, August 11, 2011

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 11, 2011

Touchdown

8:22 PM CDT (01:22 UTC)

Lifted

8:23 PM CDT (01:23 UTC)

On the ground

1 minutes

Path length

0.0 miles (0.0 km)

Path width

20 yards (18 m)

Deaths

0

Injuries

0

County

Brown County

Touchdown point

42.640, -100.060

Lift-off point

42.640, -100.060

Record number

1108111922-01

Severe thunderstorms developed in north central Nebraska on the afternoon of August 11th in the vicinity of a warm front draped from southwest South Dakota into northeast Nebraska. The storms quickly became tornadic with six tornados occurring by the end of the evening. The largest tornado was classified as an EF3 and touched down over southeast Cherry county and traveled into Brown county before lifting. The other tornadoes produced minimal damage and were rated EF0's and EF1's. Large hail also impacted these areas, with the largest size being tennis ball size.

A tornado briefly touched down in an open field eight miles north-northwest of Ainsworth. No damage occurred from this tornado and it was rated an EF0.

A tornado briefly touched down five miles north of Johnstown. No damage occurred from this tornado.

A tornado touched down and traveled southeast about one mile, crossed a road and moved another two miles before lifting. Two trees were twisted off close to the point of touch down, with no additional damage noted. The maximum wind speed was 75 m.p.h., and the tornado was rated a EF0.

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

15 minutes of warning. NWS LBF issued a tornado warning for this county at 01:07 UTC, 15 minutes before the tornado touched down, in force until 01:30 UTC.

The county was under a tornado watch, issued at 21:38 UTC and running to 07:00 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. The outlook in force was issued at 00:52 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.

Ainsworth Munici (ANW), 9 km from the path, in the two hours either side.

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

The North Platte radar (KLNX), 87 km away, was scanning. The volume nearest the touchdown began at 01:22 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 2011 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

7 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.