A wet last week of April resulted in saturated conditions and rising stream levels across portions of northwest Iowa. This helped push the Upper Little Sioux River between Milford and Spencer into Minor flood stage at the end of April which continued into May.
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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.
A wet last week of April resulted in saturated conditions and rising stream levels across portions of northwest Iowa. This helped push the Upper Little Sioux River between Milford and Spencer into Minor flood stage at the end of April which continued into May. These high flows translated downstream toward Linn Grove and Cherokee into the first week of May.
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, 9:49 PM CST, 2 hours 11 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Sioux Falls SD 1049 PM CDT Tue Apr 30 2024 .KEY MESSAGES... - Showers and storms have come to an end this evening. However, breezy northwesterly winds continue behind a cold front tonight. - Another round of additional rainfall is possible Wednesday night where rainfall amounts may exceed a half an inch of rain. Locations south of I-90 have a 50-80% chance for receiving rainfall totals greater then a half an inch. - Seasonal temperatures with highs into the 60s and 70s and lows down to the 40s will continue through the weekend. && .DISCUSSION... Issued at 303 PM CDT Tue Apr 30 2024 Showers and storms have developed across the area early this afternoon. Instability has been struggling a bit which has kept a more limited severe storm threat early this afternoon. However, current satellite shows some clearing ahead of the line which will help to destabilize thermal profiles a bit more. This looks to allow instability to increase up to around 1,000 J/kg of MLCAPE, highest along and south of highway-20. This same area has the potential for 2 inch hail given the sufficient instability and shear in place. North of this area, a line of storms has developed along I-29 and will push east through the evening hours. Damaging winds up to 70 mph are expected along with large hail up to quarter to half dollar size. An isolated tornado remains possible with the line as it pushes through the forecast area. Aside from the severe component of these storms, brief heavy rain is possible with any storm that develops which could yield minor flooding. Storms will persist through the afternoon hours before pushing east of the area this evening. Isolated showers and storms are possible after the line of storms passes through but these storms are not expected to be severe. These additional showers and storms will diminish this evening as instability runs out, leaving quiet conditions for the overnight hours. Low temperatures will fall to 40s overnight. Wednesday will be a mostly quiet day during the daylight hours. Surface high pressure will slide through the area resulting in light winds along with slightly cooler high temperatures up to the 60s. Cloud cover will be building overhead throughout the day as the next chance for rain arrives Wednesday evening. Another upper level wave will push out of the Rockies and into the Northern Plains. The cold front from Tuesday will reside well south of the area Wednesday evening but will slowly push northwards through the night. While the surface front will not reach the forecast area, the elevated front at 850 mb will as warm air advection (WAA) strengthens in response to a strengthening low level jet (LLJ). Moisture transport will increase between 925-850 mb while precipitable water (PWAT) raise to the 90th percentile of climatology per NAEFS ensemble. Soundings do show elevated instability up to a few hundred J/kg. Given the lacking instability, severe storms are not expected. Ensembles continue to support heavier rainfall as the Euro and Canadian ensembles have a broad 50-80% chance for exceeding a half an inch of rain with the highest probabilities south of I-90. The GFS ensemble is a bit of an outlier as it has its highest probabilities for exceeding the same amount of QPF across the Nebraska, Iowa, and Missouri border. Any chance for rain will push east of the area on Thursday, resulting in mainly dry and slightly cooler conditions with highs warming to the upper 50s to mid 60s. The next chance for rain comes on Friday as medium range guidance shows another shortwave trough rotates into the Northern Plains. However, surface winds will be out of the west/northwest which will keep drier low level air in place and thus keep instability to a minimum. Ensembles do vary on precipitation potential so have stuck with model blended PoPs as of now. Outside of rain chances, high temperatures look to warm to the 60s with lows falling to the 40s. The weekend looks to be mostly dry as upper level ridging prevails across the Northern Plains. High temperatures will warm to the 60s and 70s with lows only falling to the 40s and 50s. The next chance for rain looks to come early next week as ensembles show another upper wave ejecting into the Plains. Too much uncertainty resides with the wave evolution regarding rain and storm chances. Again have left model blended PoPs. Aside from rain chances, high temperatures look to remain in the 70s for the new work week. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1042 PM CDT Tue Apr 30 2024 VFR conditions overnight and into much of Wednesday. Winds tonight out of the northwest around 10 knots and gusts to 20 knots at times. As gusts weaken tonight, LLWS (around 300 degrees and 50 knots) may develop across southwestern MN and adjacent areas of SD and IA as the LLJ increases. This should stay to the east of KFSD. Direction shifts and winds will briefly become light as weak high pressure slides over the forecast area. Easterly winds prevail and increase during the late afternoon/early evening Wednesday, with gusts approaching 25 knots Wednesday night. Rain and storm chances increase from south to north through the evening hours and into Wednesday night. Have omitted thunder mention as confidence is too low in occurrence, but did increase coverage of -SHRA based on latest hi-res guidance. Expect lower end VFR conditions later in the period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && DISCUSSION...SG/Meyers AVIATION...SG
Hazardous Weather Outlook National Weather Service Sioux Falls SD 636 PM CDT Tue Apr 30 2024 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-012345- 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- 636 PM CDT Tue Apr 30 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. Severe threat has diminished. Lingering showers and thunderstorms through late evening along and east of I-29 may produce brief heavy rainfall. Breezy northwest winds expected into tonight behind a cold front, gusting at times to 35 mph. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Additional showers and thunderstorms are expected Wednesday afternoon continuing into Thursday. While severe weather is not anticipated, minor/isolated flooding issues are possible. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
7 flood. Local standard time, as filed.
Flooding on the Little Sioux River near Milford continued from late April, cresting around 2.28 feet above flood stage (14.28 feet) on May 9th. This crest is in the Moderate Stage. The river then fell below flood stage during the early morning of May 15th.
Flooding on the Little Sioux River near Milford continued from late April, cresting around 2.28 feet above flood stage (14.28 feet) on May 9th. This crest is in the Moderate Stage. The river then fell below flood stage during the early morning of May 15th.
Flooding on the Little Sioux River near Spencer continued from late April, cresting around 3.34 feet above flood stage (13.34 feet) on May 10th. The river then briefly fell below flood stage the afternoon of May 17th.
The Ocheyedan River near Spencer rose above flood stage the morning of May 2nd, cresting around 2.16 feet above flood stage (10.16 feet) on May 9th. This crest is in the Moderate Stage. The river then fell below flood stage on the evening of May 12th.
The Little Sioux River rose above Spencer rose above flood stage midday on May 2nd, cresting around 1.38 feet above flood stage (1323.38 feet) on May 9th. The river then fell below flood stage on the afternoon of May 14th.
The Little Sioux River near Cherokee rose above flood stage the evening of May 2nd, cresting around 3.98 feet above flood stage (20.98 feet) on May 10th. The river then fell below flood stage on the afternoon of May 15th.
The Little Sioux River near Cherokee rose above flood stage the evening of May 2nd, cresting around 3.98 feet above flood stage (20.98 feet) on May 10th. The river then fell below flood stage on the afternoon of May 15th.
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, May 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: 1173360, 1173361, 1173362, 1173367, 1173363, 1173364, 1173365.