On an otherwise mundane day, a small handful of funnel clouds were reported across northern Iowa. The general setup, as hinted, was lackluster with relative high pressure over the region, light wind fields, highs only in the 70s, and dew points in the upper 50s to low 60s.
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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.
On an otherwise mundane day, a small handful of funnel clouds were reported across northern Iowa. The general setup, as hinted, was lackluster with relative high pressure over the region, light wind fields, highs only in the 70s, and dew points in the upper 50s to low 60s. Convective and supporting parameters were generally weak with MUCAPE values around 500-1000 J/kg, effective bulk shear generally under 30 kts, negligible 0-1 km SRH, and lifted condensation levels around 1000 m or greater to name a few. While the wind fields were light, they may have added to localized helicity with their more chaotic directions versus any directional organization. Sporadic convection did initiate, but amounted to little more than showers and a rogue funnel cloud report or two.
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 Jul 28, 5:32 PM CST, 22 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 632 PM CDT Sat Jul 28 2018 .SHORT TERM.../Tonight through Sunday/ Issued at 333 PM CDT Sat Jul 28 2018 Surface high pressure over the northeast half of the state will continue to slide southeast through Sunday. Over the southwest, low pressure over the central/southern Plains will also slide southeast and a weak trough/boundary will exist from the low into northern Kansas and Missouri. Weak forcing and warm advection will extend north of this boundary across west central into far southern Iowa and keep the isolated showers/thunderstorms going through much of Sunday...especially across the far south. A subtle shortwave aloft is passing through the northeast and is providing enough forcing for some isolated showers/storms this afternoon but this should be short lived and not last much beyond 00Z. Soundings and time height cross sections show a fair amount of patchy low level moisture around and with light easterly winds expected, we could see patchy fog again tonight. This was included in the grids mainly after 09Z. .LONG TERM.../Sunday night through Saturday/ Issued at 333 PM CDT Sat Jul 28 2018 There has been little change to the overall pattern and forecast. An upper level trough will reside from the Great Lakes southwestward through the Upper Midwest. Subtle shortwaves will ride through the flow bringing periods of forcing and/or theta-e advection for occasional chances for showers and storms across the state. Nothing notably strong and no strong boundaries around so not really looking at any severe potential but it not be completely dry either. Towards the end of the week a Canadian system will flatten the ridge over the Rockies into the Upper Midwest and push the trough east creating a zonal flow across the region. The transition from this trough over us to a more zonal pattern will occur Wednesday into Thursday and will be our next better chance for widespread precip. This will also bring warmer temps for the region into the weekend and a little more instability but still nothing sticks out as a big weather producer or chance for widespread rainfall through the valid period of the forecast. Little change was needed to the extended with warmer temps and periodic chances for showers/storms still the main message. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 632 PM CDT Sat Jul 28 2018 A few showers and isolated thunderstorms continue to fire prior to 00z and then another round of showers/iso convection expected mainly far southern Iowa through end of period. Mainly VFR cigs north sites KFOD/KMCW with possible MVFR cigs+vsby at remaining sites...though both KFOD/KMCW may see brief fog between 09-13z Sunday as well. Winds light through period and generally east northeast. Expect cigs to lift to VFR all sites aft 18z Sunday with limited shower possibility at KOTM/KDSM from that time. Will update trends with next package. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...FAB LONG TERM...FAB AVIATION...REV
Hazardous Weather Outlook National Weather Service Des Moines IA 329 PM CDT Sat Jul 28 2018 IAZ044-045-057>059-070>073-081>086-092>097-291100- Crawford-Carroll-Audubon-Guthrie-Dallas-Cass-Adair-Madison-Warren- Adams-Union-Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur- Wayne-Appanoose-Davis- 329 PM CDT Sat Jul 28 2018 This Hazardous Weather Outlook is for portions of western, central and southern Iowa. .DAY ONE...This afternoon and tonight Isolated non severe thunderstorms are possible tonight. .DAYS TWO THROUGH SEVEN...Sunday through Friday A few thunderstorms are possible Sunday into Monday, and around midweek. Severe weather is not expected. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. IAZ004>007-015>017-023>028-033>039-046>050-060>062-074-075-291100- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Black Hawk-Greene-Boone-Story- Marshall-Tama-Polk-Jasper-Poweshiek-Marion-Mahaska- 329 PM CDT Sat Jul 28 2018 This Hazardous Weather Outlook is for portions of northern, central and eastern Iowa. .DAY ONE...This afternoon and tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday Infrequent thunderstorms are possible early this week, and then again for the middle to latter portions of next week. Severe weather is not expected. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. Small
The Des Moines radar (KDMX), 117 km away, was scanning. The volume nearest the first event began at 23:50 UTC.
3 funnel cloud. Local standard time, as filed.
A small funnel cloud was reported just below the cloud base. KCCI relayed the viewer report. Time estimated from radar.
Kossuth County Sheriff's office and KCCI viewer reported a small funnel just below cloud base. Time estimated from radar.
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, July 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: 773976, 775114, 773983.