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 the month.
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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 the month.
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, 5:22 PM CST, 1 hour 38 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Sioux Falls SD 622 PM CDT Tue Apr 30 2024 .KEY MESSAGES... - Severe weather threat has diminished. Isolated to scattered showers and storms continue through late this evening along and east of I-29. Brief heavy rainfall many occur in thunderstorms. - A second 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 /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 610 PM CDT Tue Apr 30 2024 Isolated to scattered showers/storms continue through late this evening along and east of I-29. Patchy MVFR conditions continue into late evening as well as convection tracks to the east. Otherwise, VFR conditions expected. Winds shift through the early/mid evening hours to the northwest as a cold front swings across the forecast area. Sustained winds 10-20 knots with gusts around 30 knots are possible initially behind the front, slowly tapering off through the overnight hours. Rain and storm chances return toward the end of the period, but confidence is too low to include for prevailing. Have included some mention at KSUX, but confidence in timing and coverage is low. && .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.
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
454 PM CDT Tue Apr 30 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0436 PM Hail 4 S Moneta 43.07N 95.40W
04/30/2024 M0.75 Inch O'Brien IA Public
&&
JCPreliminary Local Storm Report
National Weather Service Sioux Falls SD
458 PM CDT Tue Apr 30 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0404 PM Hail 6 S Granville 42.90N 95.88W
04/30/2024 M1.00 Inch Plymouth IA Public
&&
JCPreliminary Local Storm Report
National Weather Service Sioux Falls SD
502 PM CDT Tue Apr 30 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0402 PM Hail 5 NE Remsen 42.86N 95.91W
04/30/2024 M0.88 Inch Plymouth IA Public
&&
JCPreliminary Local Storm Report
National Weather Service Sioux Falls SD
503 PM CDT Tue Apr 30 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0418 PM Hail 1 E Paullina 42.98N 95.67W
04/30/2024 M0.75 Inch O'Brien IA Public
&&
JCPreliminary Local Storm Report
National Weather Service Sioux Falls SD
504 PM CDT Tue Apr 30 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0356 PM Hail 4 NNW Remsen 42.86N 96.00W
04/30/2024 M0.75 Inch Plymouth IA Public
&&
JCPreliminary Local Storm Report
National Weather Service Sioux Falls SD
506 PM CDT Tue Apr 30 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM Hail 4 NNE Remsen 42.87N 95.93W
04/30/2024 M0.75 Inch Plymouth IA Public
&&
JCThe national radar mosaic for the moment the first event began.
3 flood. Local standard time, as filed.
The Little Sioux River near Milford, IA rose above flood stage on the evening of April 30th with minor flooding continuing into May.
The Little Sioux River near Milford, IA rose above flood stage on the evening of April 30th with minor flooding continuing into May.
The Little Sioux River at Spencer, IA rose above flood stage on the evening of April 30th with minor flooding continuing into May.
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, April 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: 1166181, 1166182, 1166183.