EF1 tornado, Pierce to Mc Lean, Nebraska, 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 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

June 20, 2011

Touchdown

7:27 PM CDT (00:27 UTC)

Lifted

7:40 PM CDT (00:40 UTC)

On the ground

13 minutes

Path length

12.0 miles (19.4 km)

Path width

400 yards (366 m)

Deaths

0

Injuries

0

County

Pierce County

Touchdown point

42.177, -97.485

Lift-off point

42.351, -97.505

Record number

1106201827-01

11 damage points were recorded along this path by NWS OAX, in the Damage Assessment Toolkit the survey teams carry. The highest wind the damage implies is 95 mph.

• .House lost entire south side of roof. Blown across the street.
• .The house was shifted just off its foundation. Wasn't slid very far, but just shifted.
• .The house lost a small part of the roof on the north side. Also a flag pool was blown over and tree branches broke.
• .Very small, weak outbuildings distroyed.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

A large upper level low pressure system moved from northwest Kansas into south central Nebraska during the late afternoon and evening of June 20. Temperatures and dew point temperatures ahead of the low climbed to around 90 and lower 70s respectively near and south of a warm front that extended east northeast from low pressure in southwest Nebraska. Strong levels of wind shear combined with the high instability to produce several spiral bands of embedded supercell thunderstorms that produced fairly widespread wind damage and at least 2 tornadoes across the region.

An EF1 tornado was determined to cause damage from southeast of Pierce to east of Osmond. The initial damage from the tornado was noted near 522nd Avenue and 852nd Street where trees were uprooted. The tornado tracked north northwest striking a farm after it crossed Highway 98 destroying farm outbuildings and uprooting trees in the area. The tornado uprooted or caused other tree damage along its path and destroyed other farm outbuildings and flipped center pivots. In one area along its path the track became visible in a corn field. Some power poles were downed and in one case farm equipment was tossed over 300 yards while another farmstead had its debris carried nearly a quarter of a mile to the northwest. In addition, a steel bin was blown about 300 feet onto Highway 81 near the Jct. with Old Highway 98 where a car hit it injuring a man and totaling his car. A small part of a roof of a home of another farmstead was removed. A large chicken barn near Old Highway 98 had its roof blown off. The tornado appeared to weaken as it moved north toward 864th Road overturning more pivots and producing tree damage before ending near that area.

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.

The county was under a tornado watch, issued at 23:54 UTC and running to 03:03 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 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:58 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.

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

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.