A surface boundary oriented roughly west southwest to east northeast over northern Iowa provided a genesis region for thunderstorms on June 11 2025. Storms developing along this boundary moved into a very unstable environment south and east of the boundary, boasting MLCAPE values of 2500 to 3000 J/kg.
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.
A surface boundary oriented roughly west southwest to east northeast over northern Iowa provided a genesis region for thunderstorms on June 11 2025. Storms developing along this boundary moved into a very unstable environment south and east of the boundary, boasting MLCAPE values of 2500 to 3000 J/kg. Most of the better wind shear was located along and north of this boundary, but effective shear values of 30 to 40 kts along and just south of this boundary were sufficient for organized storms. Surface temperatures were also quite warm in the warm sector, with afternoon temperatures in the 90s but dewpoints only in the upper 50s to low 60s, resulting in inverted-V soundings and an environment conducive for strong cool production and downburst winds. Thunderstorms were initially discrete, producing strong downburst winds and hail. One storm in far northern Iowa, nearest to the boundary and within a more sheared environment, exhibited supercellular characteristics and produced a very strong rear-flank downdraft (RFD). Wind gusts of over 70 mph were observed with this RFD, some of which extended multiple miles south of the main storm. Personal weather stations showed a nearly 30 degree Fahrenheit temperature drop and 5 to 10 millibar pressure increase accompanying these winds as the RFD/cold pool passed through. The strong winds resulted in tree and building damage beginning near Emmetsburg through Algona and into Belmond. Another storm near Dows produced a healthy core which promptly collapsed, producing a microburst which damaged a machine shed on a farm outside Dows. Upon reaching north central Iowa, storms began to grow upscale as cold pools congealed, transitioning into a linear mode. While this transition occurred, the gust front began to outrun the storms, but continued to produce strong 50 to 60 mph winds as it trudged eastward. A plume of dust accompanied this gust front upon it's arrival in northeastern Iowa. Eventually, storms reoriented themselves along the leading edge of the cold pool, producing more tree damage and power outages throughout the Cedar Falls/Waterloo area. Strong winds continued into Tama county and eastern Black Hawk county, where a semi truck and trailer was overturned on Highway 20. Storms eventually departed the DMX forecast area in the early evening, but continued producing strong winds as they moved through eastern Iowa.
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 Jun 11, 1:18 PM CST, 1 hour 22 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Des Moines IA 218 PM CDT Wed Jun 11 2025 .KEY MESSAGES... - Severe storms possible over northern Iowa this afternoon into mid- evening with main hazards being damaging wind gusts and large hail - Locally heavy rainfall tonight over northern Iowa with isolated flash flooding possible with these chances highest in urban areas or over smaller basins - Lull in storm coverage Thursday morning with additional storms in the afternoon and early evening with limited severe chances - Not a washout, but chances for storms at times into early next week with organized storms possible early next week && .DISCUSSION... Issued at 218 PM CDT Wed Jun 11 2025 A more active period of thunderstorm chances is in store over the next week largely driven by shortwave troughs being carried through the low amplitude flow. This flow can be viewed on the upper level water vapor imagery from GOES-East with one wave over the Dakotas and Nebraska and another nearing the northern Rockies. This first shortwave is reaching the state this afternoon interacting with a stationary front that is draped over far northern Iowa from just north of Sheldon to just north of Algona to north of Waterloo. This front has provided some level of convergence despite the weak surface flow with a storm along the Iowa/Minnesota border. Expectation is that additional storms will be able to form along northern Iowa this afternoon and push eastward into early this evening. Now, the weak flow does result in weaker effective shear despite the traditional deep shear values looking favorable for storm organization. Surface based CAPE values over 1500 J/kg are common south of the front already this afternoon and with the dry mid-level air, downdraft CAPE values are over 1000 J/kg. The steep low level lapse rates and still more than sufficient SBCAPE values should allow for good parcel acceleration on storm development phase that pushes past the 12kft freezing level and into the hail growth zone. This will result in a large hail threat. Further, the large downdraft CAPE values, inverted V soundings, and surface dewpoint depressions over 20 degrees F also point to the hazard of damaging wind gusts. This is shown in various convective allowing models (CAMs) such as the 12z HRRR, 0/12z ARW cores, and 12z FV3, which have small, but varying swaths of severe wind gusts (>50 knots/58 mph) over northern Iowa this afternoon into early this evening. Already have seen severe gusts up in WFO Sioux Falls service area with the one storm this afternoon. This first wave of storms will exit into northeast Iowa mid to late evening, but regeneration of additional storms is expected over Siouxland as a weak low level jet points into that region, especially late tonight into the overnight. While severe weather is not expected, locally heavy rainfall will be possible as these storms track roughly eastward following the weak 850-300mb flow along the stalled front over northern Iowa. Efficient rainfall is certainly possible given the deep warm cloud depths and precipitable water values over 1.5 inches pooling along the boundary. Rain totals of 1 to 2 inches are possible somewhere along this boundary whether in northern Iowa or southern Minnesota. A few CAMs (e.g. ARW, HRRR, FV3) also show amounts over 4 inches in varying locations, with these CAMs impacting the localized probability matched mean of the 12z HREF. Flash flood guidance (FFG) values over northern Iowa range from 1.75 to 2 inches for 1 hour, 2 to 2.5 inches for 3 hours, and 2.5 to 3 inches for 6 hour. With relative soil moisture (RSM) percentiles in the normal range (30th to 70th percentile) at the 0-10cm and 10-40cm layers, the FFG seems a bit low from an empirical sense for mid-June. So, urban areas and/or smaller basins, if the higher rainfall moves over those areas, could have isolated flash flooding. As for rivers, monthly average USGS streamflows are average and there is capacity and expectation at this point is mainly within stream bank rises. The exception would be if one of those higher QPF CAM solutions verifies and this could result in more than within stream bank rise. As we move into Thursday, there should become a minimum in coverage of any showers or storms in the morning hours that lasts into at least part of the afternoon. The second shortwave nearing the northern Rockies today looks to pass largely north of the state Thursday afternoon and night. This would keep the focus for much of the storm activity north of the state, though a few storms may move across northern Iowa mid to late afternoon into the early evening hours. These could pose an isolated hail or gusty winds threat and is currently captured in the day 2 SPC outlook. Further south outside the marginal risk area, a few storms may develop during peak heating over central Iowa. Instability may reach 1000 J/kg, but shear is weak so outside of perhaps some sub-severe hail and wind gusts as storms collapse, the activity over central Iowa looks to be more of the sub-severe variety. Depending on where the rain falls tonight (Wednesday night/early Thursday) will determine what kind of flash flooding or river flooding risk, if any, will exist later on Thursday. Low shower and storm chances will persist in parts of the state, mainly northern and eastern Iowa on Friday as shortwave energy passes north of the state and a 500mb closed low drifts northeastward over Missouri. A front may clear the state by Saturday with this weekend favoring drier, though not fully dry conditions. The machine learning/artificial intelligence (ML/AI) severe probabilities are also low or non-existent in this period. Chances for more organized storms may develop as a warm front lifts over the region and Iowa returns to the warm sector early next week. Instability and shear parameter space would point to some strong to severe storm risk with this supported in the ML/AI severe probabilities as well. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1241 PM CDT Wed Jun 11 2025 VFR conditions will prevail at DSM and OTM through the period, but showers and storms will bring at least one or more intervals of restrictions to the other terminals late this afternoon into tonight. For ALO and MCW, higher confidence in storms passing over these terminals late this afternoon/early this evening to provide TEMPO group, though AMD to impacts is possible. After those storms move through, activity should focus over far northern Iowa and have long period of VCSH/PROB30 TSRA to cover those chances at MCW. For FOD, storm chances are higher north of this terminal, but close enough to warrant a PROB30 group. Finally, low ceilings are expected to develop before sunrise over the northern terminals before dissipating through the morning hours. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && DISCUSSION...Ansorge AVIATION...Ansorge
Hazardous Weather Outlook National Weather Service Des Moines IA 749 AM CDT Wed Jun 11 2025 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-121300- 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- 749 AM CDT Wed Jun 11 2025 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Thunderstorms will develop late this afternoon and evening across northern Iowa, possibly reaching as far south as central Iowa. Some of the stronger storms will be capable of producing large hail and gusty winds. Heavy rainfall will also be possible, especially as rain and storms redevelop tonight over northern Iowa. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Additional thunderstorm chances are forecast at intervals from Thursday through Tuesday. Some stronger storms may produce gusty winds in western and northwestern Iowa late Thursday night. Any severe weather threats from Friday onward will be better assessed in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed across the northern half of Iowa later today.
The Des Moines radar (KDMX), 173 km away, was scanning. The volume nearest the first event began at 20:41 UTC.
27 thunderstorm wind, 5 hail. Local standard time, as filed.
Strong wind gusts with large branches down reported in Emmetsburg.
Gust reported by personal weather station.
Wind gust observation from a personal weather station near Rodman.
Wind gust measured from a personal weather station near Algona.
Wind gust measured at the Algona Airport.
Multiple trees damaged with medium to large limbs down. One tree broken off at the base. One outbuilding damaged. Time estimated from radar.
Social media picture of medium to large tree branch sent through house roof. Time estimated from radar.
Nickel size hail near Wesley.
Hail ranging from dime to nickel sized.
Quarter sized or a touch larger hail east of Corwith on 150th St. Reported by Corwith Fire.
Wind gust measured by a personal weather station.
Wind gust reported by AWOS station KCAV Clarion Airport.
Trees down in Belmond. Small to large tree branches down in Belmond.
Significant damage to an outbuilding on a farm near Dows. Images found via social media.
Wind gust measured by an RWIS from the Iowa DOT.
Wind gust measured by a personal weather station.
Observed 60 mile per hour wind gust on an anemometer.
Wind gust measured by a personal weather station.
Wind gust measured by personal weather station.
Wind gust measured by a personal weather station.
Tree debris with small and medium sized branches covering the roadways.
Wind gusts around 60 mph reported in Cedar Falls.
Multiple photos of large branches down in Cedar Falls area.
Wind gust measured by a personal weather station.
Tree down on power lines resulting in power outages around Cedar Falls.
Damage to homes due to downed tree limbs.
Report of 50 mph winds with 63 mph gusts 5 mile north of Dysart.
Report of 60 mph winds with heavy rain in Traer area.
Wind gust report from personal weather station.
Semi blown over on Highway 20 east of Waterloo, southwest of Jesup.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2025Every state in 2025This day in weather historyWarnings in Iowa, June 2025
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: 1269861, 1269862, 1269852, 1277546, 1269853, 1277547, 1269864, 1269895, 1269908, 1269855, 1269914, 1269915, 1277554, 1277555, 1277589, 1277567, 1277568, 1277569, 1277572, 1277575, 1277576, 1277577, 1277578, 1277579, 1277580, 1277582, 1277583, 1277584, 1277585, 1277586, 1277587, 1277588.