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 22, 5:22 AM CST, 4 hours 38 minutes earlier.
Area Forecast Discussion National Weather Service Sioux Falls SD 622 AM CDT Sun Apr 22 2018 .SHORT TERM...(Today and Tonight) Issued at 336 AM CDT Sun Apr 22 2018 The large cut-off low pressure system to the south which has been the primary driver of conditions the over the past couple days will slowly migrate east through the day. Light winds are still in the forecast, as the area remains under broad ridging; however, the cloud cover that was ubiquitous yesterday will continue breaking up, as the weak lift and moisture associated with the low continues to move away. Temperatures will reach into the upper 50s to low 60s, which is just below normal for this time of year. .LONG TERM...(Monday through Saturday) Issued at 336 AM CDT Sun Apr 22 2018 Monday looks to be the warmest day of the next week, with plenty of sun, light southeast winds, and temperatures at to 5 degrees above normal, which would be pushing 70 degrees along the Missouri River Valley from Chamberlain through Sioux City. The enhanced ridging which brought Monday's pleasant conditions will be short-lived, as a shortwave trough moves into the area Tuesday. This wave moves through overnight and will bring a cold front through by the afternoon. Winds will shift out of the north at around 20 mph. Recent model runs continue to show variability with how much precipitation can be expected with this front, but the trend of moving the system south and west of the tri-state area seems to still be favored. A tenth to perhaps a few tenths of rain will be possible. In the wake of the front, temperatures will cool to 5 degrees below normals. The second of half of the week features a repeating pattern with Wednesday bringing a warmup as a shortwave ridge builds, then more light rain with breezy north winds on Thursday as a weak cold front again pushes across the region. Gusts could be as high as 30 to 35 mph with this more robust system. Friday into next weekend again look to feature light winds and a slow warmup as another ridge builds. Overall, it will be a quiet spring weather pattern through next weekend. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 620 AM CDT Sun Apr 22 2018 Mostly clear skies are expected, but high clouds will linger throughout much of the day. Winds will be light, gusting up to 15 kt during the afternoon hours. Winds quickly diminish after sunset. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM...VandenBoogart LONG TERM...VandenBoogart AVIATION...VandenBoogart
Hazardous Weather Outlook National Weather Service Sioux Falls SD 348 AM CDT Sun Apr 22 2018 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-230900- 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- 348 AM CDT Sun Apr 22 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...Today and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Monday through Saturday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
1 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 0.9 feet above flood stage on the Rock River at Rock Rapids (gage site RAPI4) on April 23.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2018Every state in 2018This day in weather historyWarnings in Iowa, 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: 772117.