Unrated tornado, Chancellor, South Dakota, August 28, 2021

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 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. Unratedthis tornado

   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

Unrated

Date

August 28, 2021

Touchdown

4:21 PM CDT (21:21 UTC)

Lifted

4:22 PM CDT (21:22 UTC)

On the ground

1 minutes

Path length

0.5 miles (0.7 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

County

Turner County

Touchdown point

43.342, -96.933

Lift-off point

43.344, -96.925

Record number

2108281521-01

31 damage points were recorded along this path by NWS FSD, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 95 mph.

• Shed destroyed. Sill plate attached to concrete slab completely rotten.
• East side wall blown out after west facing door failed. Soybeans laying in similar direction.
• Looking southeast. Large corn field flattened. Stalks to the east.
• Debris laid out to the northeast.

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

An unstable warm sector with MUCAPE up to 2000-2500 J/kg developed during the afternoon between an advancing cold front across southeast South Dakota and a gangly warm front extending into southwest Minnesota. An approaching weak impulse spurred rapid development of multiple rounds of storms near the warm front, initially discrete, with upscale growth into short bowing segments. Secondary development occurred during the evening along the cold front, which evolved into a slow-moving linear system with hail, wind, and heavy rainfall with shear vectors increasingly parallel to the boundary.

Based on Sentinel satellite imagery, a tornado spun up in Turner County southwest of the intersection of 279th Street and 464th Avenue. The tornado traveled east-northeast for around one-half mile through open farmland before it crossed into Lincoln County. While in Turner County, the tornado was rated EFU, but in Lincoln County it was rated EF1. The average path width in Turner County was 30 yards.

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

Sioux Falls (FSD), 30 km from the path, in the two hours either side.

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

The Sioux Falls radar (KFSD), 32 km away, was scanning. The volume nearest the touchdown began at 21:17 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.

The live radar over the trackEvery 2021 tornado in South DakotaEvery tornado in South Dakota since 1950Warnings in force in South Dakota nowThe forecast where you are

16 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.