On the evening of 26 June 2008, a compact upper level low pressure system tracking through the Northern Plains interacted with a very moist and unstable airmass over western and central South Dakota resulting in a widespread severe weather outbreak.  Three confirmed tornadoes occurred briefly in western Dewey County.  Little or no damage was reported and all three tornadoes were rated EF-0. In addition to the tornadoes, multiple reports of large hail were received over Corson and Dewey Counties, including some to the size of baseballs near the communities of McLaughlin and Isabel.  The large hail broke out many home and vehicle windows and damaged many roofs in Dewey, Corson, and Sully Counties.
Significant wind damage occurred over sections of Sully County.  There were multiple reports of wind gusts in excess of 70 mph, with the most concentrated swath of damaging winds extending from near Sutton Bay, eastward to the city of Onida, then southeast to the community of Harrold.
The storm survey began near Sutton Bay on Lake Oahe, where a wind gust of 92 mph was recorded. The most significant property damage was found further east near the community of Agar where multiple grain bins were either damaged or destroyed.  Nine miles west of Agar, a barn was destroyed and a large pine tree was snapped in half. Winds in this area were estimated to range from 80 to 100 mph.  Near the intersection of Highways 1804 and 175th Street, several Western Area Power Administration (WAPA) electrical transmission towers were completely collapsed. This is consistent with wind speeds ranging from 130-140 mph. In the city of Onida a bank roof was damaged and the city was without power until the next day.  Four miles north of Onida, a feed wagon was tossed nearly 40 feet. In Harrold, several railroad cars were tipped over.
Also of great significance during the event was the peak wind speed of 124 mph recorded at the Onida airport.  This wind speed is the strongest wind gust ever measured in the Aberdeen County Warning Area (CWA) and the 4th strongest wind speed ever reported in South Dakota.

Hail in CORSON, SOUTH DAKOTA
From 26-JUN-08 17:39:00 to 26-JUN-08 17:39:00 (MST-7)
Location: BLACK HORSE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in CORSON, SOUTH DAKOTA
From 26-JUN-08 17:45:00 to 26-JUN-08 17:45:00 (MST-7)
Location: BLACK HORSE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 17:29:00 to 26-JUN-08 17:29:00 (MST-7)
Location: WHITEHORSE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:11:00 to 26-JUN-08 18:11:00 (MST-7)
Location: TIMBER LAKE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:13:00 to 26-JUN-08 18:13:00 (MST-7)
Location: TIMBER LAKE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:05:00 to 26-JUN-08 18:05:00 (MST-7)
Location: TIMBER LAKE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:45:00 to 26-JUN-08 18:45:00 (MST-7)
Location: BEAR CREEK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in DEWEY, SOUTH DAKOTA
From 26-JUN-08 19:45:00 to 26-JUN-08 19:45:00 (MST-7)
Location: THATCHER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in STANLEY, SOUTH DAKOTA
From 26-JUN-08 21:00:00 to 26-JUN-08 21:00:00 (MST-7)
Location: FT PIERRE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in STANLEY, SOUTH DAKOTA
From 26-JUN-08 20:55:00 to 26-JUN-08 20:55:00 (MST-7)
Location: SANSARC
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in SULLY, SOUTH DAKOTA
From 26-JUN-08 20:55:00 to 26-JUN-08 20:55:00 (CST-6)
Location: AGAR
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in SULLY, SOUTH DAKOTA
From 26-JUN-08 20:59:00 to 26-JUN-08 20:59:00 (CST-6)
Location: AGAR
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tornado in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:40:00 to 26-JUN-08 18:42:00 (MST-7)
Location: RIDGEVIEW JEWETT ARP
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A tornado touched down briefly in an open field with no damage reported.

Thunderstorm Wind in HUGHES, SOUTH DAKOTA
From 26-JUN-08 21:55:00 to 26-JUN-08 21:55:00 (CST-6)
Location: HARROLD
Magnitude: 86.00 MG
Reported by: Mesonet

Thunderstorm Wind in HYDE, SOUTH DAKOTA
From 26-JUN-08 21:45:00 to 26-JUN-08 21:45:00 (CST-6)
Location: HOLABIRD
Magnitude: 61.00 EG
Reported by: Trained Spotter

Thunderstorm Wind in HYDE, SOUTH DAKOTA
From 26-JUN-08 22:00:00 to 26-JUN-08 22:00:00 (CST-6)
Location: HOLABIRD
Magnitude: 70.00 EG
Reported by: Public

Thunderstorm Wind in SULLY, SOUTH DAKOTA
From 26-JUN-08 21:15:00 to 26-JUN-08 21:15:00 (CST-6)
Location: ONIDA
Magnitude: 78.00 EG
Reported by: Law Enforcement

Damaging winds took part of the roof off the bank in Onida, knocked out the power to the city, and downed many trees in and around town.

Thunderstorm Wind in SULLY, SOUTH DAKOTA
From 26-JUN-08 21:15:00 to 26-JUN-08 21:15:00 (CST-6)
Location: ONIDA
Magnitude: 78.00 EG
Reported by: Law Enforcement

A feed wagon was tossed 40 feet by an estimated 90 mph wind.

Thunderstorm Wind in SULLY, SOUTH DAKOTA
From 26-JUN-08 21:12:00 to 26-JUN-08 21:12:00 (CST-6)
Location: ONIDA MUNI ARPT
Magnitude: 108.00 MG
Reported by: Mesonet

Hail in CORSON, SOUTH DAKOTA
From 26-JUN-08 15:42:00 to 26-JUN-08 15:42:00 (MST-7)
Location: MAPLE LEAF
Magnitude: 2.75 
Reported by: Public

Hail in CORSON, SOUTH DAKOTA
From 26-JUN-08 17:41:00 to 26-JUN-08 17:41:00 (MST-7)
Location: BLACK HORSE
Magnitude: 1.75 
Reported by: Public

Hail in CORSON, SOUTH DAKOTA
From 26-JUN-08 17:45:00 to 26-JUN-08 17:45:00 (MST-7)
Location: BLACK HORSE
Magnitude: 2.50 
Reported by: Law Enforcement

Hail in CORSON, SOUTH DAKOTA
From 26-JUN-08 17:44:00 to 26-JUN-08 17:44:00 (MST-7)
Location: BLACK HORSE
Magnitude: 2.75 
Reported by: Law Enforcement

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 17:59:00 to 26-JUN-08 17:59:00 (MST-7)
Location: FIRESTEEL
Magnitude: 2.00 
Reported by: Law Enforcement

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:02:00 to 26-JUN-08 18:02:00 (MST-7)
Location: FIRESTEEL
Magnitude: 1.75 
Reported by: Trained Spotter

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 17:50:00 to 26-JUN-08 17:50:00 (MST-7)
Location: FIRESTEEL
Magnitude: 1.75 
Reported by: Public

Hail in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:39:00 to 26-JUN-08 18:39:00 (MST-7)
Location: RIDGEVIEW
Magnitude: 2.50 
Reported by: Public

Tornado in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:10:00 to 26-JUN-08 18:14:00 (MST-7)
Location: PARADE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

A tornado touched downed in an open field for several minutes. No damage occurred.

Tornado in DEWEY, SOUTH DAKOTA
From 26-JUN-08 18:54:00 to 26-JUN-08 18:55:00 (MST-7)
Location: EAGLE BUTTE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

A third tornado touched down briefly in Dewey county. No damage was reported.