A mid-level trough sliding southeast across the Northern Plains generated numerous thunderstorms during the later afternoon and evening hours across central South Dakota. While the environment was less favorable with a much weaker shear profile toward southeast South Dakota, an isolated storm pulsed in strength near Chamberlain and produced wind damage before rapidly weakening.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS FSD wrote it up.
A mid-level trough sliding southeast across the Northern Plains generated numerous thunderstorms during the later afternoon and evening hours across central South Dakota. While the environment was less favorable with a much weaker shear profile toward southeast South Dakota, an isolated storm pulsed in strength near Chamberlain and produced wind damage before rapidly weakening.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Sioux Falls, SD wrote its last area forecast discussion before the first event at Aug 6, 5:19 PM CST, 1 hour 26 minutes earlier.
Area Forecast Discussion National Weather Service Sioux Falls SD 619 PM CDT Mon Aug 6 2018 .SHORT TERM...(This evening through Tuesday) Issued at 301 PM CDT Mon Aug 6 2018 Unsettled weather will continue this afternoon into Tuesday, influenced by a shortwave trough slowly digging east-southeast across the northern Plains. This afternoon and early evening, ahead of the approaching shortwave, daytime heating and destabilization will allow isolated thunderstorms to pop up, mainly across southeast South Dakota into the Buffalo Ridge area of MN late afternoon into the early evening. This activity will be small and unorganized spotty "popcorn" type thunderstorms and are not expected to be severe. A few stronger storms may contain gusty winds to 45 mph or small hail, but should remain below severe limits. A better chance of showers and storms will arrive mid to late evening with the shortwave slowly working into the area from the west-northwest. Scattered thunderstorm activity works its way into the area from central portions of South Dakota and Nebraska late this evening into the early morning hours. While marginally strong to severe storms will be possible west and south of the forecast area, the low level jet is much less favorable for our forecast area. This along with diminishing instability will keep the severe threat very low for areas north and east of the Missouri River (across our forecast area). Scattered showers and storms will continue to weaken through the overnight hours with brief heavy downpours and lightning being the main threats. There may be a brief break in activity Tuesday morning, however with the trough hanging over southwest Minnesota and northwest Iowa, isolated to to scattered showers will remain possible mainly east of I-29 through the afternoon, before finally exiting to the east. Not expecting a total wash-out by any means, nor is severe weather expected. Highs will be in the 80s with relatively light winds and partly cloudy skies. .LONG TERM...(Tuesday night through Monday) Issued at 301 PM CDT Mon Aug 6 2018 Recent wet weather pattern will finally come to an end as the long wave pattern gradually shifts a well amplified ridge eastward into the central US. This will direct warmer and drier weather to the region, with temperatures returning to near or slightly above normal Wednesday into the weekend. Most days will be in the 80s to lower 90s, with a few mid 90s readings in south central SD. Humidity will be reasonable, with dewpoints in the 60s, which will keep heat index values in check. Presently, there is no precipitation in the forecast Tuesday night into day 7. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 616 PM CDT Mon Aug 6 2018 Diurnal based activity will slowly diminish this evening, however more concentrated area of showers and thunderstorms over central and western South Dakota will likely continue southeast as it is more synoptically driven. Will include a prevailing mention later this evening as this activity moves through. For Tuesday, will continue to advertise dry conditions given low probability of redevelopment by mid-day. Will however add in a diurnal based CU layer through the afternoon. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM... LONG TERM... AVIATION...Dux
Hazardous Weather Outlook National Weather Service Sioux Falls SD 341 PM CDT Mon Aug 6 2018 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-072045- Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln MN-Lyon MN-Murray-Cottonwood- Nobles-Jackson-Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury- Brookings-Gregory-Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora- Davison-Hanson-McCook-Minnehaha-Charles Mix-Douglas-Hutchinson- Turner-Lincoln SD-Bon Homme-Yankton-Clay SD-Union- 341 PM CDT Mon Aug 6 2018 This Hazardous Weather Outlook is for portions of northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota, and southeast South Dakota. .DAY ONE...This Afternoon and Tonight Scattered showers and thunderstorms are possible this afternoon into the overnight hours. Severe weather is not expected. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The Aberdeen radar (KABR), 205 km away, was scanning. The volume nearest the first event began at 00:46 UTC.
2 thunderstorm wind, 1 hail. Local standard time, as filed.
Strong wind gusts at the leading edge of the storm blew a plastic play set across the yard, ripped numerous shingles off the roof and broke drain spouts. Ground was also covered by pea size hail.
Wind gusts occurred at the leading edge of the storm. Hail up to penny size also occurred, followed by heavy rainfall.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2018Every state in 2018This day in weather historyWarnings in South Dakota, August 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 779806, 779807, 779808.