An intense thunderstorm moved from northeastern Wyoming into the foothills of the northern Black Hills. Massive downburst winds estimated at 90 to 110 mph hit areas from eight miles west of Spearfish to several miles east of Spearfish. Hail to golfball size accompanied the high winds and damaged roofs and siding throughout the region, although the winds caused the worst damage. In town, the intense winds shattered signs, blew over gas station awnings and the wind driven hail caused major damage to automotive and mobile home dealerships.  A retirement home had a quarter of its roof torn off and a hotel had to evacuate all its guests as a portion of their roof was blown off. At least ten mobile homes were unlivable, and over 100 mobile homes had damage to siding, roofing and skirting. The airport at Spearfish had 27 planes damaged, and seven of those were destroyed beyond repair.  Seven hangers at the airport were also damaged or destroyed. A massive amount of trees in Spearfish were either snapped in half or completely knocked over, leaving many roads unpassable after the event.  Roofing material sliced through an oxygen valve at the Spearfish Trout Farm and killed 100,000 out of 120,000 trout that the family raised.  In the Spearfish city campground, more then 150 campers were there, in anticipation of the 60th Annual Sturgis Motorcycle Rally the following week.  Over 100 trees were blown over and many people had camping equipment, vehicles or motorcycles damaged by the falling trees. None of the trees fell on  occupied tents, although several fell within inches of where people were sleeping in their tents. 4 injuries were reported.  One of the injuries required treatment at Rapid City Medical Center after someone was injured when his camper flipped over on the interstate. East of Spearfish, highway signs were blown over, large round bales of hay were blown several yards, and more trees were blown down or snapped off.  Numerous outbuildings were also damaged, with debris scattered nearly a hundred yards downstream.  In Sturgis, the damage was not as intense.  The majority of the damage occurred to tents that were set up by vendors selling merchandise for the motorcycle rally. The most critical injury from the entire event occurred in Sturgis when a vendor was trying to keep his tent from being blown away, and he was thrown into metal scaffolding.  He was treated at the Rapid City Regional Hospital.  As the storm moved to the southeast, high winds over 60 mph were reported for nearly 45 minuted between Sturgis and Rapid City.  In Rapid City, the National Weather Service office measured wind gusts of 70 mph.  The only damage reported were tree limbs down. The storm weakened as it moved southeast of Rapid City, but was still at severe limits as it passed over the Badlands National Park and went southward into Bennett County.  Observers in Martin reported 60 mph wind gusts. The storm dissipated before reaching Nebraska.

Hail in BUTTE, SOUTH DAKOTA
From 01-AUG-00 21:31:00 to 01-AUG-00 21:31:00 (MST)
Location: BELLE FOURCHE
Magnitude: 0.75 
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in LAWRENCE, SOUTH DAKOTA
From 01-AUG-00 21:31:00 to 01-AUG-00 22:00:00 (MST)
Location: SPEARFISH
Magnitude: 95 E
Property damage: 9.5M
Reported by: NWS STORM SURVEY

Hail in LAWRENCE, SOUTH DAKOTA
From 01-AUG-00 21:31:00 to 01-AUG-00 22:00:00 (MST)
Location: SPEARFISH
Magnitude: 1.75 
Reported by: NWS STORM SURVEY

Thunderstorm Wind in MEADE, SOUTH DAKOTA
From 01-AUG-00 22:00:00 to 01-AUG-00 22:20:00 (MST)
Location: STURGIS
Magnitude: 78 E
Property damage: 500K
Reported by: NWS STORM SURVEY

Thunderstorm Wind in MEADE, SOUTH DAKOTA
From 01-AUG-00 22:10:00 to 01-AUG-00 22:45:00 (MST)
Location: PIEDMONT
Magnitude: 61 E
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in PENNINGTON, SOUTH DAKOTA
From 01-AUG-00 22:23:00 to 01-AUG-00 22:50:00 (MST)
Location: RAPID CITY
Magnitude: 61 M
Reported by: OFFICIAL NWS OBS.

Thunderstorm Wind in PENNINGTON, SOUTH DAKOTA
From 01-AUG-00 22:34:00 to 01-AUG-00 22:34:00 (MST)
Location: RAPID CITY ARPT
Magnitude: 50 M
Reported by: OFFICIAL NWS OBS.

Thunderstorm Wind in BENNETT, SOUTH DAKOTA
From 02-AUG-00 00:15:00 to 02-AUG-00 00:15:00 (MST)
Location: MARTIN
Magnitude: 52 M
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MEADE, SOUTH DAKOTA
From 01-AUG-00 22:34:00 to 01-AUG-00 22:55:00 (MST)
Location: ELLSWORTH AFB
Magnitude: 56 M
Reported by: OTHER FEDERAL AGENCY

Thunderstorm Wind in OGLALA LAKOTA, SOUTH DAKOTA
From 01-AUG-00 22:55:00 to 01-AUG-00 23:10:00 (MST)
Location: KYLE
Magnitude: 58 E
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in JACKSON, SOUTH DAKOTA
From 01-AUG-00 22:50:00 to 01-AUG-00 22:50:00 (MST)
Location: CEDAR PASS
Magnitude: 52 E
Reported by: OTHER FEDERAL AGENCY

Thunderstorm Wind in BUTTE, SOUTH DAKOTA
From 01-AUG-00 21:25:00 to 01-AUG-00 21:35:00 (MST)
Location: BELLE FOURCHE
Magnitude: 75 E
Reported by: NWS STORM SURVEY

Thunderstorm Wind in LAWRENCE, SOUTH DAKOTA
From 01-AUG-00 21:25:00 to 01-AUG-00 21:25:00 (MST)
Location: SPEARFISH
Magnitude: 59 M
Reported by: TRAINED SPOTTER

Thunderstorm Wind in LAWRENCE, SOUTH DAKOTA
From 01-AUG-00 21:25:00 to 01-AUG-00 21:30:00 (MST)
Location: SPEARFISH
Magnitude: 68 M
Reported by: TRAINED SPOTTER