EF3 tornado, (Hlc)Hill City Muni to Almena, Kansas, June 20, 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

June 20, 2011

Touchdown

1:54 PM CDT (18:54 UTC)

Lifted

2:12 PM CDT (19:12 UTC)

On the ground

18 minutes

Path length

11.9 miles (19.1 km)

Path width

600 yards (549 m)

Deaths

0

Injuries

0

Property damage

$6.0 million

Counties

Graham and Norton counties

Touchdown point

39.490, -99.872

Lift-off point

39.643, -99.778

Record number

1106201254-01

A strong, slow-moving low pressure system moved across northwest Kansas during the afternoon, resulting in over a dozen tornadoes, some strong and long-lived. The strongest tornadoes occurred over Graham and Norton counties. Other reports of baseball sized hail were received.

A strong tornado developed just west of U.S. Highway 283 north of Hill City and moved northeast into southern Norton County. The tornado produced extensive damage, including irrigation pivots overturned, utility poles destroyed, and farm implements rolled/tossed nearly 3/4 of a mile. The worst damage occurred in northern Graham County just east of Highway 283. Storm chasers reported at least one satellite tornado rotating around this main tornadic circulation.

This large tornado moved from northern Graham County into Norton County, dissipating near Norton County Road E-6 and Highway 9 west of Densmore. The tornado was still producing EF2 damage in Norton County as it destroyed utility poles, grain bins and tree rows. A farmstead suffered significant damage west of Densmore. The roof was heavily damaged, vehicles and farm implements were moved, with grain bins and outbuildings damaged or destroyed.

Storm survey team located a four-mile track of significant damage along and just south of Road S from Road 6 to Road 10. Major damage occurred to a grove of large cottonwood trees. Nearby, a farmstead received damage to outbuildings, utility poles, with the south-facing wall of the home bowed out as a result of the tornado.

A four mile path of storm damage was surveyed southeast of Calvert. A large outbuilding at a residence was completely destroyed, irrigation pivots overturned, utility poles damaged, and the back section of a house was also of heavily damaged.

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

28 minutes of warning. NWS GLD issued a tornado warning for this county at 18:26 UTC, 28 minutes before the tornado touched down, in force until 19:18 UTC.

The county was under a tornado watch, issued at 18:03 UTC and running to 03:33 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 16:04 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 Grand Island radar (KUEX), 145 km away, was scanning. The volume nearest the touchdown began at 18:57 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 KansasEvery tornado in Kansas since 1950Warnings in force in Kansas nowThe forecast where you are

37 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.