A United States record setting hailstone fell from a very strong supercell thunderstorm moving southeast across central South Dakota.  The record setting hailstone fell near Vivian, South Dakota and measured 8 inches in diameter, 18.625 inches in circumference, and weighed 1.9375 pounds. This hailstone broke the previous United States record for diameter (7.0 inches - 22 June 2003 in Aurora, NE) and weight (1.67 pounds - 3 September 1970 in Coffeyville, KS).  The Aurora, Nebraska hailstone will retain the record for circumference (18.75 inches).  Several other stones of 6 inches or more in diameter were measured during the storm survey.
Along with the very large hail, damaging winds in excess of 70 mph along with an isolated tornado occurred. The large hail and high winds caused extensive damage to homes, outbuildings, and vehicles as it moved southeast across the region. Some of the hail went completely through car windshields, roofs, garages, and campers. The hail caused five minor injuries to motorists on Interstate-90 as it went through their windshields. A minor was severely injured when the glass in the mini-van he was traveling was completely shattered by the large hail. The child suffered numerous cuts, many requiring stitches.

Hail in FAULK, SOUTH DAKOTA
From 23-JUL-10 17:15:00 to 23-JUL-10 17:15:00 (CST-6)
Location: SENECA
Magnitude: 1.75 
Reported by: COOP Observer

Hail in LYMAN, SOUTH DAKOTA
From 23-JUL-10 17:22:00 to 23-JUL-10 17:22:00 (CST-6)
Location: PRESHO
Magnitude: 1.75 
Reported by: COOP Observer

Thunderstorm Wind in JONES, SOUTH DAKOTA
From 23-JUL-10 16:48:00 to 23-JUL-10 16:48:00 (CST-6)
Location: DRAPER
Magnitude: 74.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in LYMAN, SOUTH DAKOTA
From 23-JUL-10 18:04:00 to 23-JUL-10 18:04:00 (CST-6)
Location: OACOMA
Magnitude: 63.00 MG
Reported by: Mesonet

Hail in LYMAN, SOUTH DAKOTA
From 23-JUL-10 17:35:00 to 23-JUL-10 17:35:00 (CST-6)
Location: LYMAN
Magnitude: 2.00 
Reported by: Storm Chaser

Hail in LYMAN, SOUTH DAKOTA
From 23-JUL-10 18:00:00 to 23-JUL-10 18:00:00 (CST-6)
Location: KENNEBEC
Magnitude: 3.00 
Reported by: Trained Spotter

Tornado in SPINK, SOUTH DAKOTA
From 23-JUL-10 18:50:00 to 23-JUL-10 18:55:00 (CST-6)
Location: DOLAND
Tornado F-scale: EF0
Reported by: Public

A tornado touched down south of Doland and caused minor damage to trees and a farm.

Thunderstorm Wind in SPINK, SOUTH DAKOTA
From 23-JUL-10 18:49:00 to 23-JUL-10 18:49:00 (CST-6)
Location: DOLAND
Magnitude: 52.00 EG
Reported by: Public

Sixty mph winds were estimated near Doland.

Hail in POTTER, SOUTH DAKOTA
From 23-JUL-10 16:15:00 to 23-JUL-10 16:15:00 (CST-6)
Location: GETTYSBURG
Magnitude: 1.50 
Reported by: Trained Spotter

Hail in SPINK, SOUTH DAKOTA
From 23-JUL-10 18:50:00 to 23-JUL-10 18:50:00 (CST-6)
Location: DOLAND
Magnitude: 1.75 
Reported by: Public

Tornado in LYMAN, SOUTH DAKOTA
From 23-JUL-10 16:57:00 to 23-JUL-10 16:59:00 (CST-6)
Location: VIVIAN
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A tornado touched down briefly west of Vivian with no damage reported.

Hail in LYMAN, SOUTH DAKOTA
From 23-JUL-10 17:05:00 to 23-JUL-10 17:05:00 (CST-6)
Location: VIVIAN
Magnitude: 8.00 
Reported by: NWS Storm Survey

The eight inch diameter hailstone was a United States record. The hailstone also had a circumference of 18.625 inches and weighed 1.9375 pounds. The hailstone broke the previous United States record for diameter (7.0 inches - 22 June 2003 in Aurora, NE) and weight (1.67 pounds - 3 September 1970 in Coffeyville, KS).  The Aurora, Nebraska hailstone will retain the record for circumference (18.75 inches).  Extensive damage to buildings and vehicles had occurred with this record setting stone.  Five minor injuries occurred on Interstate-90 as the large hailstones went through car windshields.

Thunderstorm Wind in CLARK, SOUTH DAKOTA
From 23-JUL-10 19:00:00 to 23-JUL-10 19:00:00 (CST-6)
Location: RAYMOND
Magnitude: 52.00 EG
Reported by: Public

Sixty mph winds were estimated southwest of Raymond.

Thunderstorm Wind in HAMLIN, SOUTH DAKOTA
From 23-JUL-10 19:58:00 to 23-JUL-10 19:58:00 (CST-6)
Location: BRYANT
Magnitude: 52.00 EG
Reported by: Trained Spotter

Sixty mph winds were estimated north of Bryant.

Hail in STANLEY, SOUTH DAKOTA
From 23-JUL-10 15:33:00 to 23-JUL-10 15:33:00 (MST-7)
Location: HAYES AIRSTRIP
Magnitude: 1.00 
Reported by: COOP Observer

Hail in STANLEY, SOUTH DAKOTA
From 23-JUL-10 15:35:00 to 23-JUL-10 15:35:00 (MST-7)
Location: HAYES AIRSTRIP
Magnitude: 1.25 
Reported by: Trained Spotter

Hail in STANLEY, SOUTH DAKOTA
From 23-JUL-10 15:35:00 to 23-JUL-10 15:35:00 (MST-7)
Location: HAYES AIRSTRIP
Magnitude: 1.75 
Reported by: Trained Spotter

Hail in JONES, SOUTH DAKOTA
From 23-JUL-10 16:45:00 to 23-JUL-10 16:45:00 (CST-6)
Location: VAN METRE
Magnitude: 1.50 
Reported by: Public

Large hail damaged the siding and broke windows in a home.

Hail in LYMAN, SOUTH DAKOTA
From 23-JUL-10 17:00:00 to 23-JUL-10 17:00:00 (CST-6)
Location: MC CLURE
Magnitude: 1.75 
Reported by: Public

Hail in FAULK, SOUTH DAKOTA
From 23-JUL-10 17:10:00 to 23-JUL-10 17:10:00 (CST-6)
Location: SENECA
Magnitude: 1.75 
Reported by: Law Enforcement

Hail in LYMAN, SOUTH DAKOTA
From 23-JUL-10 17:10:00 to 23-JUL-10 17:10:00 (CST-6)
Location: VIVIAN
Magnitude: 4.25 
Reported by: Law Enforcement