A deadly tornadic storm moved across southwest South Dakota during the late afternoon and evening of 4 June, 1999. Multiple tornadoes were observed from several supercells which moved toward the northeast from west of Chadron, NE, to near Kyle, SD between 5:30 and 8:00 PM MDT. The most severe damage occurred where the paths of these storms passed near the community of Oglala, SD.
The figure below illustrates the preliminary locations of sighted tornadoes and/or tornadic damage, as well as the path of the primary circulation (mesocyclone) within the Oglala storm which produced the tornadoes. As can be seen in the graphic, the storm which affected Oglala was initiated west of Chadron, NE (radar imagery indicated it was a "classic" supercell). The first sighting of a tornado was around 5:30 PM, north of the town of Whitney. This storm (and another supercell which developed close to the southwest) moved into extreme southeast Fall River county and southwest Shannon county between 5:45 and 6:00 PM MDT. Several sightings of tornadoes were made around 6:30 as the storms moved to the west-northwest of Pine Ridge (5-10 miles southeast of Oglala).
As the storm moved toward Oglala between 6:33 and 6:40, heavy rain and hail wrapped around the tornado making sighting difficult if not impossible. As the tornadic storm moved through the Oglala area between 6:40 and 6:50 PM, residents observed that the sky was black with rain and hail with very low visibility. After the storm passed Oglala, the WSR-88D radar indicated that the storm circulation weakened somewhat as it merged with the other supercell storm just to the south. The storm re-organized into a larger, "high-precipitation" supercell storm south of Sharps Corner around 7:15 PM. Soon after this time, several tornadoes formed east of Sharps Corner, about 5 miles to the southwest of Kyle, SD. These were the last observed tornadoes from this storm, though radar indications were that it may have remained tornadic as it approached the Hisle area in Jackson County.
Brian Klimowski and Matthew Bunkers from the NWS office in Rapid City, SD, went to the Oglala area early on June 5 to conduct a damage survey and assess the severity of this event. The damage which was observed was generally in the F1-F2 range, with the most severe damage just to the east of the main intersection in Oglala. One, perhaps two tornadoes were responsible for the most severe damage observed.
The area in and around Oglala also experienced very strong straight-line winds from the north to northwest, which accounted for F1-type damage on the western and northern parts of Oglala. The image below is typical of what was observed north and south of the main intersection in Oglala, where F1-type damage was observed.
Further to the east, several locations experienced F2-type damage. The spread of the debris indicated that there was one, and perhaps two F2 tornadoes which affected the area. One such area was near the primary church in town. Below, you can see a mix of F1 and F2 damage - from the movement of framed structures off their foundations (first below), to the destruction of an unsecured framed structure which was tossed 80 feet (second below), and the destruction of a mobile home which was sheltered within trees (third below).
One-half to three-quarters of a mile further to the east there was a more continuous region of severe (F2) damage. In this area, all of the telephone and utility poles were snapped and tossed, mobile homes were thrown over 100 yards (first below, second below) with debris strewn over a quarter of a mile, and a relatively "new" framed house was leveled (third below), with wood projectiles in the ground 100 yards downstream.
With the lack of trees and structures in the area, it was difficult to identify any "path" of the tornado(s). If the tornado was retrograding at the time it struck Oglala (moving westward as it was rotating around the mesocyclone), the damage could have been caused by one tornado. However, if the tornado(s) were moving with the storm and low-level circulation, there would likely have to be two tornadoes to explain the damage that was observed over the Oglala area.