Much of the Rock River basin received from one to two inches of liquid equivalent in the week leading up to the minor flooding, including snow melt moisture from the historic blizzard on April 14.
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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.
Much of the Rock River basin received from one to two inches of liquid equivalent in the week leading up to the minor flooding, including snow melt moisture from the historic blizzard on April 14.
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 23, 9:32 PM CST, 28 minutes earlier.
Area Forecast Discussion National Weather Service Sioux Falls SD 1032 PM CDT Mon Apr 23 2018 .SHORT TERM...(This evening through Tuesday) Issued at 307 PM CDT Mon Apr 23 2018 April showers (rain not snow) are on the way! The next measurable precipitation arrives tonight into Tuesday as a shortwave currently over the Northern Plains translates southeast into the Dakotas. Latest model runs place the highest QPF (0.10"-0.60") along and west of the I-29 corridor. Thermal profiles suggest a deep and rich BL moisture along and west of the James River, starting in the nighttime and continuing through the day on Tuesday. With that said, better chances fall across southeast SD, likely along the Missouri river valley; albeit areas along and east of I-29 could see sprinkles/very light rain. Most of the instability remains farther south of the forecast area, therefore only rain chances are anticipated. Scattered showers will begin to move across the MO river after 07Z Tuesday, then spreading east-southeast across southeast South Dakota throughout the day, before tapering off early in the evening hours. With increasing clouds and showers, Tuesday will mainly in the 50s to mid 60s over northwest Iowa. .LONG TERM...(Tuesday night through Monday) Issued at 307 PM CDT Mon Apr 23 2018 A surface ridge settles in by Wednesday, leaving the region dry with plenty of sunshine and mild temperatures. Highs will reach the upper 50s and 60s. A weak disturbance and associated cold front will move southeast from North Dakota into Iowa by Thursday. Looks to be a fast-moving system, therefore not much is expected in terms of precipitation. As for now, better chances for light rain looks to be along and east of a line from SUX to Worthington to Marshall which is where better omega lifting and saturated layer persist. Low-level layers should remain saturated so mostly cloudy conditions are still expected through mid-afternoon, bringing more sunshine by late afternoon and evening. For the remainder of the extended, temperatures will be the main feature. Building heights move in behind the frontal boundary, leaving the forecast area mostly dry. With southerly surface winds prevailing through the weekend, near to above normal temperatures are expected with highs reaching the 70s. Model guidance diverges in temperatures, bringing cooler temperatures; therefore have raised temperatures from Friday to Monday by blending Superblend and ConsRaw to produce highs in the 60s and 70s. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1025 PM CDT Mon Apr 23 2018 Showers currently moving into central South Dakota will begin to impact areas along and west of the James River after 09z tonight along with low end VFR to MVFR ceilings. KHON stands the best chance to see measurable rain, with KFSD and KSUX likely more hit or miss sprinkles or light rain. Winds will also switch to out of the north/northeast after daybreak Tuesday and become breezy at times. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM...05 LONG TERM...05 AVIATION...Kalin
Hazardous Weather Outlook National Weather Service Sioux Falls SD 951 PM CDT Mon Apr 23 2018 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-250300- Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln MN-Lyon MN-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-Lincoln SD-Bon Homme-Yankton-Clay SD-Union- 951 PM CDT Mon Apr 23 2018 This Hazardous Weather Outlook is for portions of 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 No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Minor to moderate flooding is forecast to continue through mid to late week on many rivers and streams due to the recent snowmelt. Gusty north-northwest winds Thursday will bring a potential for elevated fire danger. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
2 flood. Local standard time, as filed.
Snow melt and runoff from periods of heavier rainfall briefly produced minor flooding with impact to lowland agricultural areas. River levels reached 0.5 feet above flood stage on the Rock River near Hardwick (gage site HRDM5) on April 24.
Snow melt and runoff from periods of heavier rainfall briefly produced minor flooding with impact to lowland agricultural areas. River levels reached 0.5 feet above flood stage on the Rock River near Hardwick (gage site HRDM5) on April 24.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2018Every state in 2018This day in weather historyWarnings in Minnesota, April 2018
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: 772111, 772114.