Temperatures near normal and precipitation between 75 and 100 percent of normal across Northwest Iowa led to no change in drought status.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
Temperatures near normal and precipitation between 75 and 100 percent of normal across Northwest Iowa led to no change in drought status.
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 Apr 30, 10:11 PM CST, 1 hour 49 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1111 PM CDT Fri Apr 30 2021 .SHORT TERM...(This Evening through Saturday Night) Issued at 256 PM CDT Fri Apr 30 2021 Water vapor imagery depicts cirrus clouds moving into the region along the upper level ridge. At the surface, temperatures are in the upper 60s and lower 70s as of early afternoon, and should continue climbing another couple degrees before we lose decent radiational heating. Southeasterly surface winds are courtesy of a weak high pressure system sliding down south across MN, and is resulting in intermittent breezy conditions. As we head into the evening hours, an Alberta Clipper will begin to move into the northern plains, with a warm front expected to move into the region during the early morning hours. By Saturday morning, the forecast area will be in the warm sector throughout the day. The combination of warm air advection along with radiational heating will result in temperatures soaring into the upper 80s and lower 90s. These warm temperatures will be accompanied by breezy conditions for areas in NE NE, far SE SD, and NW IA, where gusts will be in the 30-35 mph range. North of those locations the surface pressure gradient will be much less, resulting in lower wind speeds. For the areas with the higher wind speeds, did collaborate an SPS with surrounding offices to highlight the threat for high fire danger as relative humidity values do get close to 20 percent. As the day progresses, a weak cold front associated with the aforementioned clipper will begin to slowly move southwards into the northern fringes, with no mentionable weather aside from a shift in wind direction towards northwesterly. For the evening and overnight hours, upper level flow does flatten a bit and weak shortwaves are sent towards the region. A couple weak showers and thunderstorms will be possible for locations along the MO River valley in central SD, which will be spreading eastwards throughout the overnight period and into the morning hours. .LONG TERM...(Sunday through Friday) Issued at 256 PM CDT Fri Apr 30 2021 For the rest of the morning hours on Sunday, expect the chances for rain to dwindle as the mid-level shortwave finishes pushing through the area. At the surface, the weak cold front will continue moving south bringing some slightly cooler air in behind it. Mostly cloudy skies won't make it feel like it, but afternoon temperatures will be in the lower 70s except for areas where the front won't pass through until later in the afternoon (NW IA) which could crest the 80 degree mark. Another shortwave aloft moves through the region during the afternoon and evening, likely creating another round of showers and thunderstorms. There is very little concern for any severe thunderstorms to develop, as ensemble probabilities for CAPE > 500 J/KG are fairly low and almost non-existent for 1000 J/KG, and effective shear values are similarly low due to weak mid-level flow. Upper level flow throughout the week remains fairly active as troughs will be setup across the western CONUS, with weak shortwaves being sent across the region resulting in showers and thunderstorms being possible. Current thinking is best chances occurring Wednesday morning into Thursday morning, but model agreement isn't ideal yet. Overall, temperatures do cool a bit with highs generally in the 60s and lower 70s throughout the week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1110 PM CDT Fri Apr 30 2021 Increasing flow aloft/warm advection will result in development of LLWS with a height around 1200-1500 AGL level starting late evening at KHON and spreading southeast with the advancing veering flow. By Saturday morning, areas in NW IA, and parts of SW MN, and extreme SE SD/NE NE will find developing gusty southwest surface winds, occasionally 25 to 30 kts. With decoupling ahead of a frontal boundary limping into northwest Iowa, some development of low-level wind shear is again likely on Saturday night for KSUX. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...APT LONG TERM...APT AVIATION...Chapman
Hazardous Weather Outlook National Weather Service Sioux Falls SD 437 PM CDT Fri Apr 30 2021 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-012145- 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- 437 PM CDT Fri Apr 30 2021 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...Tonight. Hazardous weather is not expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. On Saturday, a combination of low relative humidity values and strong west to southwest wind will lead to elevated fire weather concerns where dry vegetation exists. Some locations across northwest Iowa may see near critical behavior in dry vegetation areas. Wind gusts will be strongest for most areas through midday, but continued wind gusts of 20 to 30 mph will persist in parts of northwest Iowa during the afternoon. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement National Weather Service Sioux Falls SD 1000 PM CDT Fri Apr 30 2021 IAZ002-003-012>014-020>022-031-032-NEZ013-014-SDZ070-071-010900- Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Dixon-Dakota-Union- Including the cities of Sibley, Spirit Lake, Milford, Arnolds Park, Sioux Center, Orange City, Rock Valley, Hawarden, Hull, Sheldon, Hartley, Sanborn, Spencer, Le Mars, Cherokee, Storm Lake, Sioux City, Ida Grove, Holstein, Battle Creek, Wakefield, Ponca, Allen, South Sioux City, Vermillion, North Sioux City, Beresford, Elk Point, Alcester, and Jefferson 1000 PM CDT Fri Apr 30 2021 The combination of very warm temperatures, low relative humidity, and strong and gusty southwest winds will result in a high to very high fire danger on Saturday. Sustained southwest winds around 20 to 25 mph with gusts to near 35 mph are possible during the midday and afternoon Saturday when the lowest relative humidities of 18 to 30 percent will occur. It is highly recommended to not do any burning on Saturday as fires could quickly become uncontrollable.
The national radar mosaic for the moment the first event began.
2 drought. Local standard time, as filed.
Severe (D2) drought continued through May. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.
Severe (D2) drought continued through May. Crop damage is an estimate from insured losses. Information 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 2021Every state in 2021This day in weather historyWarnings in South Dakota, May 2021
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: 960270, 960271.