Diurnal destabilization produced a narrow corridor of 600-1000 J/kg MLCAPE across south central South Dakota by late afternoon on May 5. A reinforcing trough in northwest flow dropped southeast across the area in the late afternoon.
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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.
Diurnal destabilization produced a narrow corridor of 600-1000 J/kg MLCAPE across south central South Dakota by late afternoon on May 5. A reinforcing trough in northwest flow dropped southeast across the area in the late afternoon. Despite fairly weak deep-layer shear, an isolated storm briefly produced large hail.
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 May 5, 2:35 PM CST, 1 hour 22 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 335 PM CDT Tue May 5 2020 .SHORT TERM...(This Evening through Wednesday Night) Issued at 334 PM CDT Tue May 5 2020 Stubborn cloud coverage has kept us from reaching our expected highs, keeping us on the cooler side of the guidance. Light stratiform rain, primarily along and east of I-29, will continue into the evening hours and dissipate overnight. An area of scattered thunderstorms are currently heading across central SD, and will clip our far western counties (primarily: Brule, Gregory, and Charles Mix). Not expecting these storms to become strong, but some pea- sized hail and brief gusty winds are possible. The stronger wind gusts will be decreasing shortly after sunset, but will remain breezy with sustained winds between 5-10 mph. Overnight low temperatures will be in the lower 40s, with clouds remaining partly cloudy along the Missouri River Valley to mostly cloudy in SW MN. Wednesday will likely start off fairly breezy, as the departing low and entering high pressure system keep the pressure gradient strong over the area. Mid-level moisture will keep some cloud coverage around for most of the day. As the departing jet moves southeastwards, we enter the right-entrance region which provides enough lift for the global models to spit out some very light rain. High-res guidance, along with the HREF, support this but keep the activity limited to the NW IA area. To cover this possibility, have added chance for sprinkles in portions of NW IA. As the aforementioned high reaches us late in the afternoon, clouds begin clearing and the winds will be decreasing and becoming light and variable into the evening hours. Given the calm winds and recent moisture, could see some patchy fog overnight into Thursday. .LONG TERM...(Thursday through Tuesday) Issued at 334 PM CDT Tue May 5 2020 Thursday morning we enter split flow aloft with the main wave sitting over central Ontario, and a secondary wave moving towards us over the Montana/Wyoming border. At the surface, along the front edge of the inverted trough and area of weak warm air advection, rain showers begin to enter the area and work there way eastwards. Areas along the Missouri River Valley in central SD could see 3/4 of an inch of rain, becoming less as you head north and east towards I-29. Overnight lows into Friday are hovering around freezing along the I- 90 corridor, with below freezing temperatures looking likely north of I-90. Friday is looking to be dry, but due to a surface high pressure temperatures will be limited to the mid to upper 50s. Northwesterly flow aloft through the weekend continues to send shortwaves over the region, keeping us below average temperatures with chances for precipitation seemingly every other day into early next week. Due to the cooler temperatures, below freezing low temperatures are again possible Friday into Saturday and Sunday into Monday. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1203 PM CDT Tue May 5 2020 MVFR and isolated IFR ceilings will continue into the afternoon, with light rain gradually shifting east across southwest MN and northwest IA. Southwest MN will be the last to see conditions improve. Isolated afternoon thunderstorms will be possible west of the James River with small hail and wind gusts to 50 mph possible. There is a chance that MVFR ceilings copuld linger into late Wednesday morning, especially along and east of I-29. A small chance for fog west of the James River late tonight into early Wednesday morning. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...APT LONG TERM...APT AVIATION...08
Hazardous Weather Outlook National Weather Service Sioux Falls SD 333 PM CDT Tue May 5 2020 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-062045- 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- 333 PM CDT Tue May 5 2020 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 Showers and isolated thunderstorms will continue into this evening. While severe weather is not expected, any stronger storms could produce small hail and brief gusty winds, mainly west of Interstate 29. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Areas of frost are possible later this week with overnight low temperatures in the lower to mid 30s. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The Sioux Falls radar (KFSD), 148 km away, was scanning. The volume nearest the first event began at 21:56 UTC.
1 hail. Local standard time, as filed.
Crop damages are insured losses. Information is provided by the United States Department of Agriculture.
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, May 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 2026-09-30. Each event’s entry at NCEI: 889528.