Part II: Several rivers went into flood as heavy rainfall, heavy snow and resultant melting snow all led to higher streamflows in the latter half of April across portions of central and northern Iowa. Flooding at 3 locations including the West Fork of the Des Moines River at Estherville, Emmetsburg and Humboldt remained above flood stage into May 2018.
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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 DMX wrote it up.
Part II: Several rivers went into flood as heavy rainfall, heavy snow and resultant melting snow all led to higher streamflows in the latter half of April across portions of central and northern Iowa. Flooding at 3 locations including the West Fork of the Des Moines River at Estherville, Emmetsburg and Humboldt remained above flood stage into May 2018. Some of the rivers went in and out of flood a few times during the period. There are 3 parts to this event.
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 Des Moines, IA wrote its last area forecast discussion before the first event at Apr 23, 10:45 PM CST, 15 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1145 PM CDT Mon Apr 23 2018 .SHORT TERM.../Tonight through Tuesday/ Issued at 255 PM CDT Mon Apr 23 2018 Confidence: Medium to High Upper level low continues to pull away from our area with only a few mid to high level clouds still present over southern Iowa. Plenty of sunshine and a nice response today regarding mid day temperatures despite little if any mixing across the region. Tonight will remain quiet with weak ridge of high pressure settling over the region and eventually dissipating at the sfc as next system approaches. Most of Tuesday looks rather pleasant again with a general increase in clouds during the late morning to afternoon hours. Highs across the south...especially...will be mild again with H850 temperatures still ranging from 7-8C during the afternoon hours. A brief window of increased mixing in the afternoon may help promote highs in the lower 70s over the south again...with cooler afternoon highs over the north due to cloud cover and colder H850 temperatures behind a weak cold front dropping south into the region tomorrow. Highs tomorrow north will likely be in the upper 50s/lower 60s compared todays readings in the 60s. .LONG TERM.../Tuesday night through Monday/ Issued at 255 PM CDT Mon Apr 23 2018 Confidence: Medium to High With the blocking ridge aloft in place and slow moving closed low over the Southeast States...tomorrows system has little choice but to drift south/southeast with time. This has been advertised for a while and expecting again little more than chance light rain over the south/southwest tomorrow evening/night as the system tracks away from the region. Along with the cool front passing south of the area temperatures aloft will cool to slightly below zero at H850 for late tomorrow and Wednesday morning prior to eventual warming again into the weekend. This will result in slightly cooler highs for Wednesday afternoon with north northeast flow aloft. By Thursday another weak boundary will move through the region. Models differ on impacts with the Euro having a more moisture starved solution compared to the GFS. In either case the Gulf is shut off from any moisture. For now will continue with blended solution though given the pattern and predominant ridge aloft...the rain is likely to be rather sparse and of little impact. Highs Thursday should moderate ahead of the front with highs in the mid to upper 60s for the central and south and only slightly cooler in the 50s over the north. The weekend will see renewed warming with adiabatic compression across the Northern Plains resulting in warming H850 temperatures from Friday through Sunday. Some uncertainty remains with regard to the approaching system late in the weekend with a typical spread in solutions: The Euro is slower while the GFS brings the system into the region already by Monday afternoon while the Euro later Monday night. Its likely that much of the region will be in the 60s to lower 70s again already by Saturday with Sun/Mon seeing highs generally in the 70s. Sun/Monday H850 temperatures range from 10-15C/13-16C respectively. Depending on cloud cover and mixing next Monday...some potential to crack the 80 degree mark over the west/southwest. Will wait and see how trends compare over the next several days. With slower Euro solution there would be a better chance of seeing the warmer high temperatures. && .AVIATION.../For the 06Z TAFS through 06Z Tuesday night/ Issued at 1145 PM CDT Mon Apr 23 2018 VFR conditions will prevail for the next 24 hours. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...REV LONG TERM...REV AVIATION...Martin
Hazardous Weather Outlook National Weather Service Des Moines IA 317 PM CDT Mon Apr 23 2018 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-242030- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene- Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper- Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union- Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne- Appanoose-Davis- 317 PM CDT Mon Apr 23 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday River flooding due to snow melt is expected to continue or develop along the upper reaches of the Des Moines River Basin, as well as the Cedar River near Cedar Falls. Flood Warnings remain in effect for these areas. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed. REV
The national radar mosaic for the moment the first event began.
2 flood. Local standard time, as filed.
The West Fork of the Des Moines River at Humboldt crested at 10.72 feet on 26 April 2018 at 10:15 UTC.
The Cedar River at Cedar Falls crested at 89.23 feet on 25 April 2018 at 19:00 UTC.
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: 751724, 751725.