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Wintry Conditions Over The Rockies, Heavy Rainfall And Flash Flooding Threat Over The Desert Southwest

Remnant moisture from what was once Tropical Storm Raymond will continue to produce heavy rainfall and the threat for flash flooding over the Desert Southwest into Thursday. Some of the flooding could be locally significant. Heavy snow will be common over the Rockies and will likely cause hazardous travel conditions. Read More >

Overview

A deadly tornadic storm moved across southwestern South Dakota during the late afternoon and evening of 4 June, 1999. Multiple tornadoes were observed from several supercells that moved toward the northeast from west of Chadron, NE, to near Kyle, SD between 5:30 and 8 pm MDT. The most severe damage occurred where the paths of these storms passed near the community of Oglala, SD.

The figure to the right 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 that produced the tornadoes. As can be seen in the graphic, the storm that affected Oglala initiated to the 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 Whitney, NE. This storm (and another supercell that developed close to its southwest) moved into extreme southeastern Fall River county and southwestern Oglala Lakota county between 5:45 and 6:00 pm MDT. Several sightings of tornadoes (likely of the same one or two 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 pm, 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 Rapid City WSR-88D radar indicated that the storm circulation weakened somewhat as it merged with the other supercell storm just to its south. The storm reorganized into a larger, "high-precipitation" supercell south of Sharps Corner around 7:15 pm. Soon after this time, another tornado (with multiple sightings) formed east of Sharps Corner, about 5 miles to the southwest of Kyle, SD. This was the last observed tornado from this storm, though radar indications suggest that it may have remained tornadic as it approached the Hisle area in Jackson County.

Preliminary locations of sighted tornadoes and/or tornadic damage
Storm damage photo

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