Heavy rainfall in early September resulted in flooding across much of northern and central Iowa with flooding occurring a bit later along the Raccoon River at Perry than in other rivers situated further to the north and east.
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.
Heavy rainfall in early September resulted in flooding across much of northern and central Iowa with flooding occurring a bit later along the Raccoon River at Perry than in other rivers situated further to the north and east.
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 Sep 7, 5:31 PM CST, 59 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 631 PM CDT Fri Sep 7 2018 .SHORT TERM.../Tonight through Saturday/ Issued at 257 PM CDT Fri Sep 7 2018 Primary forecast concern is heavy rainfall potential in the southeast tonight into early Saturday, along with cloud cover and temperature trends. Forecast Confidence: Medium Synoptic pattern this afternoon features modest southwesterly flow aloft over the Midwest...with a weak reflection of the remains of Gordon to our south. At the surface, a strong high pressure center is located north of Lake Superior a weak low associated with Gordon over AR/MO. Still seeing a very distinct moisture boundary residing over IA with a very moist, tropical-like airmass across the south and southeast with a much drier airmass north. 12Z RAOBS depicted this nicely with the KDVN 850mb dewpoint of +16C /PWAT 1.62"/ with KMSP 850mb dewpoint of -30C /PWAT 0.73"/. Radar mosaic as of 3 pm showed a continuation of showers over the southeastern CWA although the overall coverage has diminished somewhat the past couple hours. Temps this afternoon remain rather cool, with readings generally in the 60s. For tonight...good model agreement showing the circulation associated with the remains of Gordon lifting north into MO. Tightening gradient on the north side of the circulation will produce strengthening 925/850mb winds of 30-50kts. Excellent deep moisture convergence signal in the models over southeast IA and northern MO. The combination of this moisture convergence, weak ascent associated with the right entrance region of 300mb jet and the deep moisture profiles/high PWAT environment is expected to result in a resurgence of moderate to heavy precipitation over southeastern IA tonight. Model consensus still shows the heaviest QPF axis southeast of our area...however still feel that the Davis/Wapello/Monroe/Appanoose/Wayne county area could easily pick up 0.5" to 1.0" with higher amounts possible depending on where the best moisture convergence develops. Due to the weak lapse rate environment, MUCAPE values are minimal but kept mention of isolated thunder in the forecast. With all this in mind, decided to leave the Flash Flood Watch in place for now as there is still enough potential for at least modest water problems. Saturday...the low pressure system will eject off to the northeast with precip ending by afternoon as drier air filters into the area. Still expecting quite a bit of cloud cover on Saturday especially in the south and east, with more sunshine expected northwest. Temperatures will be rather tricky due to cloud cover trends, with highs generally in the mid/upper 60s. Winds will also be rather breezy out of the east/northeast from 10 to 20 mph. .LONG TERM.../Saturday night through Friday/ Issued at 257 PM CDT Fri Sep 7 2018 Forecast Confidence: High After the system clears on Saturday evening, looking like a quiet and very pleasant stretch of weather from Sunday into most of next week. Zonal upper flow will transition to upper ridging across the upper Midwest. This will result in mostly clear skies and a gradual warming trend. Expect highs in the 70s on Sunday and Monday with upper 70s to lower 80s Tuesday thru Thursday. Lows will feel fall-like on Saturday and Sunday night with lows in the upper 40s to lower 50s. Lows will moderate into the 50s and 60s by late in the week. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 631 PM CDT Fri Sep 7 2018 Low CIGS to still impact KDSM and especially KOTM tonight with VFR conditions expected for much of Saturday as drier air moves in beneath an area of high pressure and the remnants of Gordon move eastward away from the state. Winds to become more northeasterly to easterly through the period. Some showers still possible at KDSM and KOTM, with some VSBY restrictions possibly late tonight at KOTM. A very small chance of thunder, but very uncertain show have left any thunder mention out right now. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Saturday morning for IAZ084>086- 095>097. && SHORT TERM...Fowle LONG TERM...Fowle AVIATION...Beerends
Hazardous Weather Outlook National Weather Service Des Moines IA 320 PM CDT Fri Sep 7 2018 IAZ084>086-095>097-081100- Lucas-Monroe-Wapello-Wayne-Appanoose-Davis- 320 PM CDT Fri Sep 7 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Tonight The potential for heavy rainfall and a few non severe thunderstorms exists through tonight. A Flash Flood Watch has been issued for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters may be needed for flooding and heavy rainfall reports. IAZ039-050-059-081100- Black Hawk-Tama-Dallas- 320 PM CDT Fri Sep 7 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Tonight River Flood Warnings remain in effect for portions of the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .DAYS TWO THROUGH SEVEN...Saturday through Thursday River Flood Warnings remain in effect for portions of the area into the weekend. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed. IAZ004>007-015>017-023>028-033>038-044>049-057-058-060>062- 070>075-081>083-092>094-081100- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Crawford-Carroll-Greene-Boone- Story-Marshall-Audubon-Guthrie-Polk-Jasper-Poweshiek-Cass-Adair- Madison-Warren-Marion-Mahaska-Adams-Union-Clarke-Taylor-Ringgold- Decatur- 320 PM CDT Fri Sep 7 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed.
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
The North Raccoon River at Perry crested at 15.50 feet on 8 September at 1645 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, September 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: 785699.