A very moist and unstable atmosphere was present in the wake of earlier day convection, as another stronger mid-level wave and associated frontal boundary pushed through southeast South Dakota and southwest Minnesota during the evening and early overnight hours. Widespread convection along the boundary later in the evening led to areas of damaging wind and excessive rainfall in east central…
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The episode as NWS FSD wrote it up.
A very moist and unstable atmosphere was present in the wake of earlier day convection, as another stronger mid-level wave and associated frontal boundary pushed through southeast South Dakota and southwest Minnesota during the evening and early overnight hours. Widespread convection along the boundary later in the evening led to areas of damaging wind and excessive rainfall in east central South Dakota and southwest Minnesota.
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 31, 5:00 PM CST, 2 hours 25 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Sioux Falls SD 600 PM CDT Wed Jul 31 2024 .KEY MESSAGES... - Level 3 of 5 risk for severe weather this afternoon and evening. Timing is still somewhat uncertain, but latest thinking would delay onset and may reduce coverage across our forecast area. Still looking at a potential for large hail (2+ inches) and wind gusts in excess of 70 mph where storms do form, are the main hazards. Although risk is low, a tornado cannot be ruled out. - Locally heavy downpours may also bring 2+ inches of rain to isolated locations today and tonight. - Light showers or an isolated thunderstorm may linger into Thursday east of I-29. Otherwise, near normal temperatures and mostly dry conditions into the weekend. && .DISCUSSION... Issued at 318 PM CDT Wed Jul 31 2024 LATE THIS AFTERNOON-TONIGHT: Despite abundant near surface moisture as evident in mid-upper 70s dew points across the region, broad cloud debris from convection to our north and south, along with a stabilizing wave that pushed north across southeast SD over the past couple of hours. This along with a slightly slower timing of the approaching wave looks to be delaying the onset of storms across our forecast area this afternoon. Current thinking now has a low chance of convection in our area through 5-6pm, with increasing potential thereafter as new storms developing ahead of the upper wave in north central SD move east and develop southward. This would mainly impact areas north of, to perhaps near I-90 this evening, with the threat diminishing by 11pm to midnight. Given the robust instability above our stable near-surface layer, still think that large to significant hail is a possibility, along with wind gusts in excess of 70 mph. Locally heavy rain also remains a secondary threat given precipitable water approaching 2 inches, warm cloud depths exceeding 11-12kft and 850mb dew points even nearing 70F/20+C. THURSDAY-SATURDAY: Strong upper ridge builds across the western CONUS, placing our forecast area in weak flow aloft, especially for Thursday-Friday. Could still see some lingering clouds and/or some instability showers in our far east Thursday with cyclonic flow around the back side of the departing upper wave. If that occurs, it could hold temps a bit cooler over southwest MN/Iowa Great Lakes. Overall, though, if we can fully mix we should be looking at highs in the 80s Thursday, climbing a few degrees into the mid 80s to lower 90s Friday, warmest in south central SD. Thermal ridge ahead of a subtle wave on Saturday could allow for slightly warmer temperatures building in on Saturday, especially in our western counties. This area will be more likely to mix down slightly lower dew points, though, so currently looking at heat indices holding shy of advisory criteria. SATURDAY NIGHT-WEDNESDAY: Aforementioned wave flattens the ridge across the Dakotas/Minnesota, allowing the northern jet stream to dip into the far northern CONUS for the latter half of the week and into next week. This could bring a return to a more active pattern for the later periods of this forecast, along with temperatures that are near to perhaps even slightly below normal for early August. However, details at this range are low confidence given variations among the models. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 555 PM CDT Wed Jul 31 2024 Storms have been slow to develop across the area this afternoon, and confidence in timing and coverage continues to be low. Even so, some thunderstorm activity is expected to develop this evening, and any storms will be capable of producing hail to 2 inches and wind gusts to 60 kts. Any addition, locally heavy rain will be possible in heavier storms. Much of the activity will track east of the area after 06Z, though a few stray showers may linger east of Interstate 29 even into Thursday. With low pressure moving across the area, winds will be variable in the evening, trending to northwesterly later tonight into Thursday. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && DISCUSSION...JH AVIATION...JM
Hazardous Weather Outlook National Weather Service Sioux Falls SD 413 PM CDT Wed Jul 31 2024 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-012115- 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- 413 PM CDT Wed Jul 31 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...Tonight. Although uncertainty remains in timing and coverage, thunderstorms are expected by this evening through late tonight. Strong to severe storms are possible with large hail up to 2 inches and wind gusts to 70 mph. Although risk is low, a tornado cannot be ruled out. Rainfall amounts exceeding 2 inches may occur, leading to ponding of water in low lying or urban areas or isolated flash flooding. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot and humid conditions return late week and into the weekend with heat index values in the upper 90s. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed.
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
650 PM CDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0642 PM Hail Burke 43.18N 99.29W
07/31/2024 M1.00 Inch Gregory SD Law Enforcement
&&Preliminary Local Storm Report
National Weather Service Sioux Falls SD
817 PM CDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0756 PM Tstm Wnd Gst 4 ENE Alexandria 43.67N 97.71W
07/31/2024 M66 MPH Hanson SD Mesonet
Mesonet station 213 SD RWIS Alexandria.
0755 PM Tstm Wnd Gst 1 S Volga 44.30N 96.92W
07/31/2024 M58 MPH Brookings SD Mesonet
Mesonet station VGAS2 Volga (SD Mesonet).
&&The Sioux Falls radar (KFSD), 83 km away, was scanning. The volume nearest the first event began at 01:24 UTC.
5 thunderstorm wind. Local standard time, as filed.
Thunderstorm wind gusts were measured at the Minnesota Road Weather Information System site near Lake Benton, with a peak gust of 64 mph at 1928 CST.
A large tree limb from 6 to 10 inches in diameter was downed by thunderstorm wind gusts.
Thunderstorm wind gusts up to 60 mph were measured at a Minnesota Road Weather Information System site near Dovray.
Thunderstorm wind gusts up to 58 mph were measured at the Minnesota Road Weather Information System site near Beaver Creek.
Thunderstorm wind gusts up to 59 mph were measured at the Minnesota Road Weather Information System site near Magnolia.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2024Every state in 2024This day in weather historyWarnings in Minnesota, 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 2026-09-24. Each event’s entry at NCEI: 1206028, 1206027, 1206029, 1206031, 1206032.