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.

Tornado in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:22:00 to 28-AUG-21 15:25:00 (CST-6)
Location: LENNOX
Tornado F-scale: EF1
Property damage: 75.00K
Reported by: NWS Storm Survey

Based on Sentinel satellite imagery, the tornado spun up in Turner County around 2 miles west southwest of Lennox in a field southwest of the intersection of 464th Avenue and 279th Street. The tornado tracked east-northeast for around one-half mile and crossed into Lincoln County just south of the intersection of 279th Street and 464th Avenue. After another half mile, the tornado uprooted seven large cottonwood trees and damaged numerous others at the Lenkota Country Club.  The tornado continued into the western portions of Lennox north of the city park, with a majority of damage to large trees between 4th and 5th Avenue as the path turned more eastward and eventually a bit southeastward.  The most significant damage occurred as the tornado approached State Highway 17, with a trampoline deposited high in a gnarled tree along South Cherry Street, and the complete destruction of a shed just east of Highway 17.  The tornado lifted about a quarter mile east of Highway 17, just east of Lennox.  Areas south of the path experienced strong rear-flank winds. While in Turner County, the tornado was rated EFU, while in Lincoln County it was rated EF1. The average path width for the tornado was 100 yards. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:23:00 to 28-AUG-21 15:25:00 (CST-6)
Location: LENNOX
Magnitude: 74.00 EG
Property damage: 3.00M
Reported by: NWS Storm Survey

Most of the rubber roof liner on the section of Lennox High School with the band and shop classrooms was removed by thunderstorm winds. Interior ceilings and equipment incurred water damage. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:40:00 to 28-AUG-21 15:42:00 (CST-6)
Location: HARRISBURG
Magnitude: 53.00 MG
Reported by: Mesonet

Wind gust was measured by a personal weather station.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:40:00 to 28-AUG-21 15:42:00 (CST-6)
Location: CANTON
Magnitude: 61.00 EG
Reported by: Social Media

Thunderstorm wind gusts downed a large tree.

Funnel Cloud in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:45:00 to 28-AUG-21 15:47:00 (CST-6)
Location: HARRISBURG
Reported by: Trained Spotter

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:45:00 to 28-AUG-21 15:48:00 (CST-6)
Location: HARRISBURG
Magnitude: 61.00 EG
Reported by: Trained Spotter

Branches from a large cottonwood tree were blown upward and landed on the roof of a house.

Flash Flood in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 21:14:00 to 28-AUG-21 22:00:00 (CST-6)
Location: TEA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Significant street flooding continued along Heritage Parkway and 271st Street.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:24:00 to 28-AUG-21 15:26:00 (CST-6)
Location: LENNOX
Magnitude: 83.00 EG
Property damage: 30.00K
Reported by: NWS Storm Survey

One shed was completely destroyed, and two were left with damaged doors, roofs and east facing walls when strong thunderstorm wind gusts plowed through a business on the south edge of Lennox. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:28:00 to 28-AUG-21 15:30:00 (CST-6)
Location: WORTHING
Magnitude: 69.00 EG
Property damage: 10.00K
Reported by: NWS Storm Survey

Metal roof pieces from a house were blown across the county road to the east.  Several trees were gnarled with limbs down. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:26:00 to 28-AUG-21 15:28:00 (CST-6)
Location: LENNOX SKIE ARPT
Magnitude: 74.00 EG
Property damage: 10.00K
Reported by: NWS Storm Survey

Thunderstorms winds ripped the west end off a barn roof after door failure. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:30:00 to 28-AUG-21 15:32:00 (CST-6)
Location: WORTHING
Magnitude: 70.00 EG
Property damage: 15.00K
Reported by: Public

Two semi-trucks were flipped by thunderstorm wind gusts a little south of Exit 68 on Interstate 29. Property damage costs are a rough estimate.

Hail in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 17:55:00 to 28-AUG-21 17:58:00 (CST-6)
Location: HARRISBURG
Magnitude: 1.00 
Reported by: Public

Hail in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 17:55:00 to 28-AUG-21 17:58:00 (CST-6)
Location: HARRISBURG
Magnitude: 1.00 
Reported by: Public

Hail in MCCOOK, SOUTH DAKOTA
From 28-AUG-21 17:58:00 to 28-AUG-21 18:00:00 (CST-6)
Location: SALEM
Magnitude: 1.75 
Reported by: NWS Employee

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:26:00 to 28-AUG-21 15:27:00 (CST-6)
Location: LENNOX
Magnitude: 52.00 EG
Reported by: NWS Storm Survey

A narrow path of crop damage, possibly related to a miso vortex within a broader wind field, was identified using Sentinel satellite imagery.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:30:00 to 28-AUG-21 15:31:00 (CST-6)
Location: WORTHING
Magnitude: 61.00 EG
Property damage: 10.00K
Reported by: NWS Storm Survey

A car dealership sign was destroyed by thunderstorm wind gusts. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:31:00 to 28-AUG-21 15:33:00 (CST-6)
Location: WORTHING
Magnitude: 78.00 EG
Property damage: 25.00K
Reported by: NWS Storm Survey

Several power poles were snapped by thunderstorm winds. Property damage costs are a rough estimate.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:36:00 to 28-AUG-21 15:38:00 (CST-6)
Location: HARRISBURG
Magnitude: 70.00 EG
Property damage: 30.00K
Reported by: NWS Storm Survey

Thunderstorm wind gusts caused partial collapse of a pair of grain bins. Property damage costs are a rough estimate.

Flash Flood in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 21:30:00 to 28-AUG-21 23:30:00 (CST-6)
Location: SOUTH SIOUX FALLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

As a response to 3 to 5 inches of rainfall across the southern portions of Sioux Falls, the Big Sioux at Western Avenue (gage site WAVS2) climbed into flood stage at 2130CST, with a crest 0.94 feet above flood stage at 2230CST.  The Sioux Falls Marathon, which was scheduled to begin at 0530CST, was cancelled due to the overnight flash flooding.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:22:00 to 28-AUG-21 15:23:00 (CST-6)
Location: LENNOX
Magnitude: 70.00 EG
Reported by: NWS Storm Survey

Thunderstorms winds uprooted several pine trees in a row at the Lennox Cemetery.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:23:00 to 28-AUG-21 15:25:00 (CST-6)
Location: LENNOX
Magnitude: 81.00 EG
Reported by: NWS Storm Survey

Several large trees trunks were snapped in the city park.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:23:00 to 28-AUG-21 15:25:00 (CST-6)
Location: LENNOX
Magnitude: 74.00 EG
Property damage: 15.00K
Reported by: NWS Storm Survey

The west facing roof was removed from a metal outbuilding by strong thunderstorm wind gusts. Property damage costs are a rough estimate.

Hail in MCCOOK, SOUTH DAKOTA
From 28-AUG-21 18:20:00 to 28-AUG-21 18:23:00 (CST-6)
Location: SALEM
Magnitude: 1.75 
Reported by: Public

Hail varied from half-dollar to golf ball size.

Hail in MCCOOK, SOUTH DAKOTA
From 28-AUG-21 18:50:00 to 28-AUG-21 18:53:00 (CST-6)
Location: CANISTOTA
Magnitude: 1.50 
Reported by: Social Media

Flash Flood in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 20:02:00 to 28-AUG-21 21:15:00 (CST-6)
Location: TEA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Numerous roads in Tea were under water. Significant flooding with up to 2 feet of water was reported on portions of 271st Street and Heritage Parkway.

Flash Flood in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 20:51:00 to 28-AUG-21 22:00:00 (CST-6)
Location: SIOUX FALLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

The roadway of 6th Street and Cliff Avenue was estimated to around a foot deep.

Flash Flood in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 20:50:00 to 28-AUG-21 22:50:00 (CST-6)
Location: EAST SIOUX FALLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Water pooled up to two feet deep in the backyard of an apartment complex near 41st Street and South Dakota Highway 11.

Flash Flood in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 20:54:00 to 28-AUG-21 22:00:00 (CST-6)
Location: ELLIS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Ponding of water caused water to reach basements.

Flash Flood in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 20:57:00 to 28-AUG-21 22:00:00 (CST-6)
Location: ELLIS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Significant ponding of water resulted in some basement flooding.

Tornado in TURNER, SOUTH DAKOTA
From 28-AUG-21 15:21:00 to 28-AUG-21 15:22:00 (CST-6)
Location: CHANCELLOR
Tornado F-scale: EFU
Reported by: NWS Storm Survey

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.

Hail in TURNER, SOUTH DAKOTA
From 28-AUG-21 15:15:00 to 28-AUG-21 15:17:00 (CST-6)
Location: HURLEY
Magnitude: 1.00 
Crop damage: 11.00K
Reported by: Emergency Manager

Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.

Tornado in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:35:00 to 28-AUG-21 15:36:00 (CST-6)
Location: WORTHING
Tornado F-scale: EFU
Reported by: NWS Storm Survey

A tornado spun up 4 miles northeast of Worthing, one-half mile north of 278th Street just east of 475th Avenue. The tornado tracked northeast for a little over a mile before it lifted 4 miles south of Harrisburg, just southwest of the intersection of 277th Street and 476th Avenue.  Damage was limited to crops with the path defined on Sentinel satellite imagery. The average path width was 20 yards.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:39:00 to 28-AUG-21 15:40:00 (CST-6)
Location: HARRISBURG
Magnitude: 52.00 EG
Crop damage: 42.00K
Reported by: NWS Storm Survey

A narrow path of crop damage, possibly related to a miso vortex within a broader wind field, was identified using Sentinel satellite imagery. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:26:00 to 28-AUG-21 15:28:00 (CST-6)
Location: LENNOX
Magnitude: 64.00 EG
Reported by: NWS Storm Survey

Several trees had large limbs of 3 to 6 inch diameter broken off by thunderstorm winds.  A flag pole was bent.

Thunderstorm Wind in TURNER, SOUTH DAKOTA
From 28-AUG-21 15:19:00 to 28-AUG-21 15:21:00 (CST-6)
Location: HURLEY
Magnitude: 61.00 EG
Crop damage: 5.00K
Reported by: Emergency Manager

Wind gusts estimated by Emergency Manager. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.

Flash Flood in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 21:13:00 to 28-AUG-21 22:30:00 (CST-6)
Location: ELLIS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Significant ponding and flooding of a small creek resulted in some basement flooding in lower spots.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:31:00 to 28-AUG-21 15:32:00 (CST-6)
Location: WORTHING
Magnitude: 64.00 EG
Reported by: NWS Storm Survey

Thunderstorm winds snapped several 6 to 12 inch diameter limbs.

Hail in MCCOOK, SOUTH DAKOTA
From 28-AUG-21 14:32:00 to 28-AUG-21 14:34:00 (CST-6)
Location: CENTER
Magnitude: 1.00 
Reported by: Trained Spotter

Tornado in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:25:00 to 28-AUG-21 15:26:00 (CST-6)
Location: LENNOX
Tornado F-scale: EFU
Reported by: NWS Storm Survey

Based on Sentinel satellite imagery and confirmed with ground survey, a brief tornado spun up around 2 miles east of Lennox, just west of the Mount Olivet Cemetery.  The tornado tracked east-northeast for less than one mile across open fields and wetlands, and dissipated 3 miles east-northeast of Lennox near the intersection of 278th Street and 468th Avenue. The average path width was 20 yards.

Tornado in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:30:00 to 28-AUG-21 15:32:00 (CST-6)
Location: WORTHING
Tornado F-scale: EFU
Reported by: NWS Storm Survey

This tornado formed 2 miles north-northwest of Worthing, around one-half mile east of Interstate 29 and north of 278th Street.  The tornado tracked northeast and then east-northeast for around one and one-half miles across open farmland and lifted 3 miles north-northeast of Worthing just south of 277th Street. The average path width, identified by crop damage in Sentinel satellite imagery, was 20 yards.

Hail in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 17:52:00 to 28-AUG-21 17:55:00 (CST-6)
Location: CANTON
Magnitude: 1.25 
Reported by: Social Media

Hail in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 18:16:00 to 28-AUG-21 18:19:00 (CST-6)
Location: CANTON MUNI ARPT
Magnitude: 1.00 
Crop damage: 575.00K
Reported by: Trained Spotter

Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.

Thunderstorm Wind in TURNER, SOUTH DAKOTA
From 28-AUG-21 15:07:00 to 28-AUG-21 15:10:00 (CST-6)
Location: HURLEY
Magnitude: 61.00 EG
Reported by: Trained Spotter

Pickup truck was blown around the road by thunderstorm wind gusts.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:24:00 to 28-AUG-21 15:27:00 (CST-6)
Location: LENNOX
Magnitude: 63.00 MG
Reported by: Mesonet

Thunderstorm wind gust was measured by a personal weather station.

Thunderstorm Wind in MINNEHAHA, SOUTH DAKOTA
From 28-AUG-21 15:38:00 to 28-AUG-21 15:40:00 (CST-6)
Location: SIOUX FALLS
Magnitude: 56.00 EG
Reported by: Public

A large tree was knocked onto a fence at the Spencer Dog Park.

Thunderstorm Wind in LINCOLN, SOUTH DAKOTA
From 28-AUG-21 15:40:00 to 28-AUG-21 15:42:00 (CST-6)
Location: HARRISBURG
Magnitude: 56.00 EG
Reported by: Public

Thunderstorm wind gusts resulted in significant tree damage.

Thunderstorm Wind in TURNER, SOUTH DAKOTA
From 28-AUG-21 15:18:00 to 28-AUG-21 15:19:00 (CST-6)
Location: CHANCELLOR
Magnitude: 74.00 EG
Property damage: 25.00K
Reported by: NWS Storm Survey

Several power poles snapped by thunderstorm wind gusts. Property damage costs are a rough estimate.