During the overnight, a slow moving convective cluster within an environment with a strong low-level jet and abundant deep-layer moisture slid from western to southern Minnesota. Storms continually regenerated on the southwest flank of the cluster, with a boundary remaining stationary for several hours from south of Marshall to north of Westbrook.
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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.
During the overnight, a slow moving convective cluster within an environment with a strong low-level jet and abundant deep-layer moisture slid from western to southern Minnesota. Storms continually regenerated on the southwest flank of the cluster, with a boundary remaining stationary for several hours from south of Marshall to north of Westbrook. Some areas had more spotty heavy rainfall the prior night, and new rainfall amounts were generally from 2 to 4 inches in the band with radar estimates between of 4 to 6 inches. Numerous city and some rural roadways were inundated.
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 17, 2:25 AM CST, 1 hour 38 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Sioux Falls SD 325 AM CDT Sun Aug 17 2025 .KEY MESSAGES... - Training thunderstorms over southwest Minnesota may result in localized flash flooding through early this morning. - Next chances for organized convection come by this evening into tonight with isolated strong to severe storms with large hail, damaging winds, and heavy rainfall. - Much quieter conditions likely return for much of the week bringing in lower dew points, near-normal temperatures, and limited precipitation chances. && .DISCUSSION... Issued at 322 AM CDT Sun Aug 17 2025 A frontal boundary currently resides from roughly east central SD into southwestern MN very early this morning. Training thunderstorms have developed along this boundary during the overnight period - fed by moisture transport on a 20-25 kt low level jet. Will have to keep an eye on this area through the early morning hours for flash flooding potential. Models have the front continuing to lift slow to the northeast, being situated along our northern CWA border by 12Z. Related to that, the current convection should also lift northward with most hi-res guidance placing it to the north our area by that time. Another area of convection that developed over northwestern SD has been moving to the east/northeast, and all hi-res guidance now keeps this to the our northwest through the reminder of the night. For today, an upper level trough presently oriented through the western Dakotas and Nebraska will shift eastward into our area by this afternoon and evening - this as a cold front over central SD also begins to track eastward. While most guidance suggest only low chances for showers and storms through at least early afternoon, will see increasing chances for scattered thunderstorms by late afternoon/early evening as a shortwave lifts out of NE and into our area during that timeframe. Showers and thunderstorms then look to become more prevalent tonight as the main upper level trough swings through the region and a low level jet again strengthens from eastern NE into eastern SD. Although shear will be fairy weak (20-30 kts) and mid level lapse rates not overly impressive (6-7 C/KM), MUCAPE by afternoon and early evening will be running around 2500 to over 3000 J/KG. In light of that, cannot rule out isolated strong to severe storms with half dollar size hail and wind gusts of 60-70 mph with DCAPE of 1000-2000 J/KG depending on model of choice. At this time, the highest risk for thunderstorms will occur from approximately 6pm this evening to 3am tonight. It will be another hot and muggy day with highs in the mid 80s to lower 90s combined with dew points in the mid to upper 70s. This will yield afternoon heat index values in the lower 90s to around 100 - with the highest values south of interstate 90. Although some areas will near Heat Advisory criteria, with the uncertainty in regard to afternoon thunderstorm potential and its impact on temperatures, elected not to issue any headlines at this time. it will be another mild night tonight with lows in the upper 60s to lower 70s. The frontal boundary finally begins to push southward out of the area during the day on Monday. With that, shower chances should taper down during the day. While weak cold air advection begins to work into the area, it will still be a warm and muggy with highs in the mid 80s to lower 90s with dew points in the lower to mid 70s. With the frontal boundary sitting just to the south of our area on Monday night, some guidance would suggest showers and thunderstorms developing south of Interstate 90 as another shortwave tracks through the area. Confidence is low however, with models varying on how far south the activity develops - with some keeping it to the south of our CWA. Severe chances look low with the better instability migrating southward and shear looking meager. For Tuesday into next weekend, the upper level flow over our area transitions to northwesterly as an upper level ridge builds through the Rockies. This pattern looks to bring quieter conditions to our area through at least midweek. Along with that, temperatures settle back closer to typical seasonal averages. By the end of the week, an upper level trough over western Canada shifts east, flattening out the aforementioned ridge. This trough shifts into the Northern Plains toward Friday, with the surface reflection trough/cold front pushing through our area on Friday. This may bring our next best chance precipitation along with cooler temperatures for next weekend. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1014 PM CDT Sat Aug 16 2025 MVFR ceilings look to be a little more stubborn across areas mainly north of I-90 through the overnight hours. Some patchy MVFR ceilings may linger through the morning as well. Attention turns to thunderstorm potential with a few strong storms possible in southwest MN and west along highway 14 through the early overnight hours. Much of this activity is expected to shift north of highway 14. The a stronger wave moves into the area on Sunday with periodic chances for thunderstorms through the late morning into Sunday evening. Some of these storms could be severe with heavy rainfall. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && DISCUSSION...JM AVIATION...08
Hazardous Weather Outlook National Weather Service Sioux Falls SD 435 AM CDT Sun Aug 17 2025 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-180945- 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- 435 AM CDT Sun Aug 17 2025 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. Training thunderstorms over southwest Minnesota will result in localized flash flooding through early morning. Heat index values between 90 and 102 degrees are expected this afternoon with the highest values south of I-90. Isolated to scattered thunderstorms may develop again late this afternoon into tonight. A few of these storms could be severe with hail to the size of half dollars and wind gusts to 65 mph. .DAYS TWO THROUGH SEVEN...Monday through Saturday. A few storms are again possible Monday evening. Details remain uncertain but storms may be capable of producing large hail and damaging wind gusts. Please continue to monitor for forecast and thunderstorm risk changes. .SPOTTER INFORMATION STATEMENT... Spotter activation will be possible tonight.
The Sioux Falls radar (KFSD), 114 km away, was scanning. The volume nearest the first event began at 10:01 UTC.
3 flash flood, 1 flood. Local standard time, as filed.
Widespread flooding occurred in Tracy between Rowland Street and Front Street and from S 1st Street to S 4th Street, which required pumping of water.
Heavy rainfall caused water to overrun 170th Street between 190th and 200th Avenue. The roadway was closed as water remained ponded over the road for several hours.
Heavy rainfall caused inundation and persistent flooding of County Road 6 between U.S. Highway 59 and County Road 35, resulting in closing of the road for several hours.
Several county roads were under water and closed for several hours after the initial flooding, including 170th Street northwest of Balaton and County Road 6 south of Marshall.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2025Every state in 2025This day in weather historyWarnings in Minnesota, August 2025
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: 1290884, 1290887, 1290893, 1290900.