An upper-level low pressure area dropped southeast across southern Minnesota through the day. A few storms popped up along a weak low-level convergence zone with up to 1500 J/kg MLCAPE and generally weak deep-layer shear in proximity to the boundary.
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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.
An upper-level low pressure area dropped southeast across southern Minnesota through the day. A few storms popped up along a weak low-level convergence zone with up to 1500 J/kg MLCAPE and generally weak deep-layer shear in proximity to the boundary. Storms organized briefly into supercells with deviant motions and produced large hail and torrential rainfall.
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 10, 11:25 AM CST, 2 hours 5 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Sioux Falls SD 1225 PM CDT Wed Jul 10 2024 .KEY MESSAGES... - Additional showers and storms are expected to develop this afternoon into the evening, mainly east of I-29. Severe storms are not anticipated, but one or two could produce localized wind gusts and small hail. - Wildfire smoke aloft will be transported into the region via upper level northerly winds. There may be some reduced visibility west of the James River as some smoke may be mixed to the surface. Smoke should track further east as the flow shifts this weekend. - Convection risks for Friday night into Saturday morning. Storms look to be focused along and east of I-29. There remains uncertainty in the severity of the storms. - Temperatures rise by the end of the week and through next weekend. Confidence is high in widespread moderate heat risk levels with potential for major levels. Sunday is the most likely timeframe for headline conditions. && .DISCUSSION... Issued at 347 AM CDT Wed Jul 10 2024 Some areas of patchy, dense fog are possible this morning in low laying areas and along river and creek beds. Any fog is expected to burn off quickly after sunrise. Water vapor imagery clearly shows a short wave working it's way southeast into eastern South Dakota, western Minnesota and Iowa. This wave is associated with an area of increased vorticity advection and weak WAA which is triggering showers and thunderstorms. As the morning continues, these showers and storms are expected to continue to move southeast into western Minnesota and Iowa through the day. Severe weather is not anticipated as the best shear looks to remain just west of the area of showers and storms. However, increasing mid-level lapse rates and 500-1300 J/kg of MLCAPE along with the aforementioned vorticity could support a few storms capable of producing small hail, gusty winds, and possibly brief funnels/landspouts. East of I-29, showers linger into the evening before clearing out overnight. Rainfall totals should remain on the light side, a tenth or two. Under stronger showers up to a half inch is possible. A thicker plume of smoke from the Canadian wildfires will be brought south on the upper level northerly winds. Subsidence behind the shortwave will bring some smoke nearer to the surface. This is indicated as well by the HRRR and RAP13 near surface integrated smoke models. Both indicate enough smoke being brought to the surface that it may begin to impact air quality. Sensitive populations may need to take precautions. Heights rise as a ridge builds in from the west Thursday into Friday. Surface winds turn southerly and WAA begin to warm things up considerably. 850 mb temperatures Thursday afternoon reach the upper teens to low 20 degrees C. With good afternoon mixing expected, surface temperatures will warm into the low 80s east of the James River, and upper 80s to the west. Additional subsidence is evident in model soundings for Friday. Compressional heating of the 900-850 mb layer coupled with another day of good mixing will warm temperatures at the surface into the mid 80s east of the James River, and 90s west. While we look to remain strongly capped, there is enough elevated instability to support some strong to severe thunderstorms Friday afternoon/evening. This far out uncertainty on placement and timing is high, but it is something to keep in mind if you have outdoor plans this Friday night. This weekend will be hot and humid. Highs are forecasted to soar into the upper 80s to mid 90s Saturday, and low to upper 90s Sunday. A few 100 degree temps are possible out toward central South Dakota. Ensemble guidance for Sunday continue to indicate a >90% probability for highs of 90+ degrees and a 20-40% probability of exceeding 100 degrees over central South Dakota. These highs are at the 90th and 99th percentile for climatology, respectively. Southerly winds transport Gulf moisture northward into the region, pushing dewpoints into the upper 60s and low 70s. As mentioned in the previous discussion, we are entering peak evapotranspiration which can result in a low bias from the NBM. However, the NBM came in a bit more aggressive with dew points this run, and so I did not feel the need to adjust them. The resulting apparent temperatures will be just under 100 Saturday, and nearing 105 along the Missouri River counties for Sunday. This is within NWS guidance for heat risk products. Areas most likely to need a headline are the counties along the Missouri River, and areas of central South Dakota. A cold front moves through the area Monday, bringing some relief from the heat. It also brings the next chance for thunderstorms, though it is too far out to speculate on their severity yet. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1217 PM CDT Wed Jul 10 2024 Beginning to see some diurnally driven CU develop across the area, which could bring some scattered showers and storms, mainlyalong/east of I-29. Lower confidence in coverage and development further north, so have included mention at KSUX but not KFSD. Will continue to monitor trends. Wildfire smoke aloft is leading to milky skies, and any surface impacts (reduced visibility) currently reside in ND. However, if smoke is mixed down, could see periods of MVFR visibility west of the James River. Light variable to northeast winds this afternoon become lighter and variable once again tonight. Could see some patchy fog in river valleys and other low lying areas into Thursday morning. For now, have left mention out of all three TAF sites. Outside of convection, smoke, and fog, VFR conditions prevail. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && DISCUSSION...AJP AVIATION...SG
Hazardous Weather Outlook National Weather Service Sioux Falls SD 406 AM CDT Wed Jul 10 2024 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-110915- 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- 406 AM CDT Wed Jul 10 2024 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...Today and tonight. Showers and weak thunderstorms along and east of I-29 will continue through the afternoon. Smoke from Canadian wildfires will be brought south via upper northerly winds. Some of this may make its way to the surface and may be enough to degrade air quality. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Summertime heat and humidity move into the region by the end of this week and into the weekend. Saturday highs will be in the upper 80s and 90s, Sunday in the 90s to 100s. Humidity will also increase, and that combined with the heat will result in apparent temperatures reaching the upper 95-100 degrees, with 105 possible along the Missouri River Valley. Those with sensitivity to excessive heat should monitor the latest forecast and be prepared to take precautions if needed. A cold front moves through Monday bringing a respite from the heat. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Sioux Falls radar (KFSD), 88 km away, was scanning. The volume nearest the first event began at 19:30 UTC.
3 hail. Local standard time, as filed.
Hail was mostly penny to nickel size, with a few stones as large as quarters.
Golf ball size hail fell along U.S. Highway 18 around 2 miles east of the city center of Sheldon.
Crop damage monetary losses are an estimate using data from the U.S. Department of Agriculture.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2024Every state in 2024This day in weather historyWarnings in Iowa, July 2024
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: 1203589, 1203590, 1203591.