River flooding continued from late April at a few locations along the West Fork of the Des Moines River through early to mid May.
Every event with a place to put it. Tap one for its entry below.
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.
River flooding continued from late April at a few locations along the West Fork of the Des Moines River through early to mid 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 Des Moines, IA wrote its last area forecast discussion before the first event at Apr 30, 10:01 PM CST, 1 hour 59 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1101 PM CDT Mon Apr 30 2018 .UPDATE... Issued at 835 PM CDT Mon Apr 30 2018 Updated to increase precipitation chances late tonight especially across the northern half and into early Tuesday morning based on the latest HRRR and 18z NAM. Trends for activity across SD/NE to move across Iowa late tonight into early Tuesday. Will continue to monitor as the 00Z NAM comes in and may increase from high chance into likely at times. Currently just trended upward into high chance for now. .PREVIOUS UPDATE... Issued at 714 PM CDT Mon Apr 30 2018 Updated to extend the wind advisory for one more hour based on numerous sites still hitting advisory criteria with strong and gusty winds. Bufkit suggests majority of the area will decouple by 8 pm, so did not extend it further at this time. Winds will diminish with sunset, however breezy conditions are still expected through the night. && .SHORT TERM.../Tonight through Tuesday/ Issued at 343 PM CDT Mon Apr 30 2018 Confidence: Medium to High Main concerns remain the wind and increasing thunderstorm threat. Subjective H850 analysis at 12z currently shows narrow ribbon of moisture streaming north into the High Plains/Western Plains with substantial dry line west of the plume over New Mexico and far western Texas. Strong H850 flow will help to direct the moisture plume into eastern Nebraska/South Dakota later tonight. Series of weak impulses will ride north with the larger upper level system from later tonight into Tuesday afternoon...setting the stage for periods of showers and stronger thunderstorms. Tonight will remain breezy but wind advisory will be allowed to expire at 7 pm as winds decouple enough to lessen gusts. None the less...breezy conditions will continue to push milder and moister air into the region through 12z. This will keep overnight lows in the upper 50s to lower 60s over the area tonight. Along with that scattered showers and thunderstorms will move across the region from 06z through 12z and then weaken during the morning hours. By mid to late afternoon an approaching cold front from the northwest will likely be the initial focusing mechanism for increasing shower and thunderstorm activity. The south looks to escape development during the afternoon hours due to lack of forcing and wind shear. By late afternoon storms firing over eastern Nebraska/Northwest Iowa will begin to expand east/southeast with some threat for severe weather continuing into the evening hours as 0-6km bulk shear increases over the south and remainder of the area. The greater severe threat here remains large hail and potentially some wind into the afternoon hours. Highs tomorrow will be highly dependent on cloud cover. With morning cloud cover likely to break up somewhat due to mixing over the south... highs should move into the upper 70s to lower 80s over the south. The greater uncertainty lies over the northwest where the boundary, cloud cover and potential occasional showers/iso thunder is likely to keep temperatures closer to the 70 degree mark. .LONG TERM.../Tuesday night through Monday/ Issued at 343 PM CDT Mon Apr 30 2018 Bottom Line up Front... Strong to severe weather potential and moderate to heavy rainfall hazardous weather threats Tuesday PM through Thursday PM. Uncertainty in overall progression of system leading to low-medium confidence of severe threat. Synoptics... Little change in overall synoptic pattern evolution for this long term fcst period. By 00z Wed, closed upper low/longwave trough over the Intermountain West still digging down through California. Run-to-run consistency still not solid with the overall progression of this system... with long-range models and their members deviating in their level of flatness/amplitude of the trough/low. Long-range models have shown good consistency of propagating trough Iowa Thursday, placing it near the Great Lakes Region by Friday, with high pressure building into the Midwest by this upcoming weekend. Have gone with a general model consensus as confidence lacks to highly favor or rule out individual model outputs. Tuesday PM Through Wed AM... Beginning at 00z Wed, focus will be on ongoing convection across Iowa. Concerns exists with what we will be seeing at that time, convection-wise. A notable, impactful 24-hr shift in location of severe threat here. Yesterday at this time, it appeared a sfc low would trek across northern Minnesota into towards Lake Superior, with its attendant cold front dropping down through northern Iowa during peak heating. Today, that low is faster and further north. Further, its attendant cold front now stalls out across northwestern Iowa and becomes more or less assimilated with the boundary of the surface center ejecting off the longwave trough that is expected to impact SE Nebraska Tuesday PM. Convection will likely wane and become capped by 06z Tue... though precip will likely continue as the LLJ remains placed through Iowa. Wednesday... Wednesday still appears to be the most active of the next 3 days across the DMX CWA. Aforementioned boundary/stationary front will be focus/trigger for convection. It's location will be key as frontogenetical ascent processes will likely be needed to punch through the 750mb cap. Not enough confidence to pin down precise location of boundary yet as run-to-run variability still remains. Orientation of the boundary is more SW-NE today, whereas yesterday it was more WSW-ENE. At this time, most likely location of the boundary near peak heating seems to be running near Crawford county in western Iowa through Butler county towards northeastern Iowa. Convection window looks to close fairly and notably quickly with loss of daytime heating, so severe weather to wane by 03z Thu, if not sooner. Decent moisture advection processes remain in play through the day Wednesday, so am expecting widespread precipitation, especially in southern Iowa where a reinforcing band of 925mb-850mb moisture flux convergence well-phased with theta-e advection may setup with PWATs nearing 1.5 inches. Thursday... Boundary will sag southward through Iowa during the daytime hours as core of longwave trough/closed upper low begins its eastward push through the Midwest. As with Wednesday, location of boundary during peak heating will be focus for severe weather potential. Another boost of moisture transport into Iowa...mainly confined to SE Iowa looks to occur Thursday afternoon, helping to keep precip going. Impact-wise, southern Iowa can handle a fair amount of rain given their ongoing drought/dry status. Friday Into the Weekend... As mentioned above, the longwave trough finally departs to the east by Friday morning and NW Flow rapidly fills into the state, drying us out heading into the weekend. Pieces of the subsequent thermal ridge building over the intermountain west may eject off into Iowa as long-range models depict a few shortwaves pushing through the Midwest. Ultimately, what this means is there will likely not be a prolonged cool-down during this time period, with persistence being a closer bet than cooler air. && .AVIATION.../For the 06Z TAFS through 06Z Tuesday night/ Issued at 1101 PM CDT Mon Apr 30 2018 Storms moving from SD and NE into IA overnight. Starting to lose their intensity, so have mainly kept VCSH in the TAFS overnight. Chances for storms again into by Tuesday afternoon/evening. Southerly winds through the period. Still strong low level winds aloft with some low level wind shear possible through 12z. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && UPDATE...Beerends SHORT TERM...REV LONG TERM...Kotenberg AVIATION...Beerends
Hazardous Weather Outlook National Weather Service Des Moines IA 812 PM CDT Mon Apr 30 2018 IAZ004>007-015>017-023>028-033>039-044>050-011200- 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- 812 PM CDT Mon Apr 30 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Tonight Isolated non severe thunderstorms are possible late tonight. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are possible Tuesday into Thursday. There is the potential for isolated severe storms along with locally heavy rain, mainly during the late afternoon into evening hours each day. The main threat of any strong to severe storms will be large hail and damaging winds. River flooding due to snow melt is expected to continue along the upper reaches of the Des Moines River Basin. 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... Spotter activation will be a possibility this week. IAZ057>062-070>075-081>086-092>097-011200- Audubon-Guthrie-Dallas-Polk-Jasper-Poweshiek-Cass-Adair-Madison- Warren-Marion-Mahaska-Adams-Union-Clarke-Lucas-Monroe-Wapello- Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis- 812 PM CDT Mon Apr 30 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Tonight An isolated non severe thunderstorms is possible late tonight. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are expected on Tuesday with some severe storms likely. The severe threat include large hail, damaging winds, and even a few isolated tornadoes possible. Additional thunderstorms are expected on Wednesday afternoon and evening with another threat of a few severe storms. Once again, large hail and damaging winds will be the main threat. An isolated tornado is also possible with the initial development in the afternoon. Thursday will present another threat of thunderstorms across central and southern Iowa. Additional severe storms will be possible during this time. Localized heavy rain will be possible each day. .SPOTTER INFORMATION STATEMENT... Spotter activation is likely to occur at times this week. MJB
The national radar mosaic for the moment the first event began.
3 flood. Local standard time, as filed.
The West Fork of the Des Moines River at Estherville crested twice through the period, the first time at 10.98 feet on 9 May 2018 at 21:45 UTC. The second crest was at 11.27 feet on 12 May 2018 at 5:30 UTC.
The West Fork of the Des Moines River at Emmetsburg crested at 11.33 feet on 2 May 2018 at 12:00 UTC.
The West Fork of the Des Moines River at Humboldt crested at 11.3 feet on 5 May 2018 at 10:30 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, May 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: 755387, 755388, 755389.