A few thunderstorms developed along a cold front approaching Interstate 29 in the late afternoon, with MLCAPE of 1500-2000 J/kg. Storms quickly become outflow dominant and produced damaging wind.
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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 few thunderstorms developed along a cold front approaching Interstate 29 in the late afternoon, with MLCAPE of 1500-2000 J/kg. Storms quickly become outflow dominant and produced damaging wind.
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 Jul 3, 2:46 PM CST, 57 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 346 PM CDT Fri Jul 3 2020 .SHORT TERM...(This Evening through Saturday) Issued at 338 PM CDT Fri Jul 3 2020 A weak boundary along the I-29 corridor will be the focus for scattered showers and thunderstorms for the rest of this afternoon and into the evening hours. The air mass will be supportive of a few storms with lightning, small hail, gusty outflow winds, and brief heavy rain, given CAPE in the 1500 to 2000 J/kg range. The lift being produced by the weak weather system overhead is not expected to cause widespread convection, but should be enough to continue to overcome the capping inversion in a few places through sunset. Forcing for ascent wanes with the setting sun, and skies clear overnight. Temperatures remain mild with overnight lows in the upper 60s to low 70s. Independence Day is looking dry for those in Sioux Falls, Sioux City, and the surrounding areas. An upper level ridge over the region strengthens slightly, suppressing any surface-based, diurnal- heating lift. Temperatures will be warm, with highs in the upper 80s and low 90s combined with mostly sunny skies. .LONG TERM...(Saturday Night through Friday) Issued at 338 PM CDT Fri Jul 3 2020 Temperatures remain warm with humid dew points in the upper 60s and low 70s over the rest of the upcoming week. The ridge overhead this weekend weakens with the jet stream slowly pushing southward causing a more zonal flow pattern by Monday. Some models show a shortwave moving through the region overnight into Tuesday morning, and this looks to be the next chance for widespread rain and thunderstorms. Wednesday is forecast to be the warmest day of the next week with low to mid 90s due to enhanced mixing ahead of a larger weather system moving eastward across the Canadian border. This system will likely drape a cold front across the region Wednesday night. The surface high behind this front is not overly strong; the air mass moderates significantly as it moves southeastward down the High Plains, so don't expect a lot of relief from the muggy warmth. Another upper ridge builds next weekend keeping summery conditions in place. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1237 PM CDT Fri Jul 3 2020 Light southeast winds prevail over the next 24 hours. Scattered mid-level cumulus clouds are likely through the daytime hours, decreasing in coverage overnight. Thunderstorms are unlikely, but a few isolated storms could form along a weak boundary that stretches down the I-29 corridor through KFSD. Lightning would be the main threat with any storms that manage to form. Have kept mention of TS out of the TAFs for the time being, given a less than 20 percent of storms impacting any given location. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...VandenBoogart LONG TERM...VandenBoogart AVIATION...VandenBoogart
Hazardous Weather Outlook National Weather Service Sioux Falls SD 350 PM CDT Fri Jul 3 2020 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-042100- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-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-Bon Homme-Yankton- Union- 350 PM CDT Fri Jul 3 2020 This Hazardous Weather Outlook is for 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 thunderstorms this afternoon and evening may bring brief heavy rain, lightning, small hail, and gusty outflow winds. Heat index values this afternoon will rise into the 90s, increasing the potential for heat related illness. Those spending time outdoors will need to take precautions, such as staying hydrated and taking more frequent breaks. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Afternoon heat indices remain in the 90s Saturday into next week, increasing the potential for heat related illnesses. Be sure to drink plenty of fluids and take frequent breaks if working outside. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement National Weather Service Sioux Falls SD 327 PM CDT Fri Jul 3 2020 IAZ001-002-012-020-031-MNZ071-072-080-089-097-098-NEZ013-014- SDZ039-040-054>056-061-062-066-067-069>071-040100- Lyon-Osceola-Sioux-Plymouth-Woodbury-Lincoln-Murray-Nobles- Pipestone-Rock-Dixon-Dakota-Kingsbury-Brookings-Miner-Lake-Moody- McCook-Minnehaha-Turner-Yankton-Clay-Union- Including the cities of Rock Rapids, George, Inwood, Larchwood, Sibley, Sioux Center, Orange City, Rock Valley, Hawarden, Hull, Le Mars, Sioux City, Tyler, Hendricks, Lake Benton, Ivanhoe, Marshall, Slayton, Fulda, Worthington, Pipestone, Luverne, Wakefield, Ponca, Allen, South Sioux City, De Smet, Arlington, Lake Preston, Brookings, Howard, Madison, Orland, Flandreau, Salem, Canistota, Bridgewater, Montrose, Sioux Falls, Parker, Centerville, Marion, Viborg, Irene, Hurley, Chancellor, Canton, Lennox, Tea, Harrisburg, Yankton, Vermillion, North Sioux City, Beresford, Elk Point, Alcester, and Jefferson 327 PM CDT Fri Jul 3 2020 Isolated showers and thunderstorms along a weak boundary this afternoon and early evening may be caple of producing weak funnel clouds. These funnels are not expected to reach the ground, but if they do, will be short lived. If you feel your safety is threatened, please seek shelter.
The Sioux Falls radar (KFSD), 61 km away, was scanning. The volume nearest the first event began at 21:43 UTC.
5 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds snapped off a single power pole. Property damage costs are rough estimates.
South Dakota RWIS station SD508 measured a peak wind gust of 60 mph.
A personal weather station measured a wind gust to 74 mph.
Strong thunderstorm winds downed a few 3 inch diameter tree limbs. Property damage costs are rough estimates.
Shingles were blown off a house with a few tree limbs downed by thunderstorm winds. Property damage costs are rough estimates.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2020Every state in 2020This day in weather historyWarnings in South Dakota, July 2020
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: 907592, 907595, 907596, 907593, 907594.