Flash Flooding and Flooding in Iowa, May 20 to 22, 2024

Name: Flash Flooding and Flooding in Iowa, May 20 to 22, 2024
Start: 2024-05-20T05:00
End: 2024-05-22T20:00
Location: Iowa

May 20 to 22, 2024 · NWS DMX · 156 events in 34 counties and zones

PLEASE NOTE, for tornadoes, please see separate Storm Data entry for May 21st. Multiple rounds of thunderstorms brought torrential rainfall, damaging winds, hail and destructive tornadoes to the state.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $1.1 million
Crop damage: None recorded
Events: 156

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.

What happened

The episode as NWS DMX wrote it up.

PLEASE NOTE, for tornadoes, please see separate Storm Data entry for May 21st.

Multiple rounds of thunderstorms brought torrential rainfall, damaging winds, hail and destructive tornadoes to the state. These thunderstorms were the result of a low pressure system which lifted north into the area on the night of May 20th, 2024, producing slow moving storms that dropped 2 to 4 inches of rainfall. This resulted in flash flooding over portions of northern and central Iowa through the morning of May 21st, 2024. State level damage estimates to public infrastructure exceeded 7 million dollars due to the morning flooding.

Following the heavy rainfall through the morning, skies cleared out ahead of an approaching cold front. By the afternoon hours of May 21st, 2024, this cold front produced a line of strong thunderstorms which produced multiple strong tornadoes throughout the state, including one which led to significant damage in the town of Greenfield, IA, among other locations. This line of storms also produced damaging winds, leading to widespread tree damage and power outages throughout the forecast area.

What forecasters said that day

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 May 20, 3:24 AM CST, 1 hour 36 minutes earlier. Its key messages:

Generally non-severe MCV associated convection lingers into the morning east, then chances temporarily diminish later in the day
More storms expected tonight into early Tuesday morning. Severe storms possible, mainly a wind treat.
Peak severe potential Tue afternoon with another round of storms. Tornadoes, damaging wind, and hail all possible. Enhanced Risk of severe weather (3/5).
Break from precip follow midweek, but additional chances return late in the week

Area forecast discussion, May 20, 3:24 AM CST, 1 hour 36 minutes before

Area Forecast Discussion
National Weather Service Des Moines IA
424 AM CDT Mon May 20 2024

.KEY MESSAGES...

- Generally non-severe MCV associated convection lingers into
  the morning east, then chances temporarily diminish later in
  the day

- More storms expected tonight into early Tuesday morning. Severe
  storms possible, mainly a wind treat.

- Peak severe potential Tue afternoon with another round of
  storms. Tornadoes, damaging wind, and hail all possible.
  Enhanced Risk of severe weather (3/5).

- Break from precip follow midweek, but additional chances
  return late in the week

&&

.DISCUSSION...
Issued at 424 AM CDT Mon May 20 2024

Little change in the overall weather pattern is anticipated
through the period with relatively lower amplitude and
progressive flow bringing systems of varied strength through the
Midwest every few days keeping us active. At onset this
morning, the parent short wave and combined generative MCV
continues to swirl along the IA/MO border with the last of the
healthy forward flank convection exiting the area to the east.
Non-severe showers and a few storms are then expected to linger
for several more hours before a temporary break with little to
no precip in the MCV's subsident wake into at least early
afternoon.

Some regeneration may occur during the late afternoon and
especially early evening hours northwest however as the current
NE/SD boundary sags into the state. This may start what could be
an active night with 2-3K J/kg MLCAPEs building into the state,
and effective shear increasing as well as the western long wave
trough nears and mid level flow increases. This convection may
persist and expand into the night, fueled by increasing low
level moisture transport through the MO Valley. This may also be
reinforced by an advancing MCS generated from what was High
Plains peak heating convection as it maintains intensity from
the low level jet associated moisture transport and convergence
crossing NE into IA. Hail and especially damaging wind appear to
the primary threats with 00Z HREF high wind probs quite high into
IA, even several hours past daybreak. Highly anomalous moisture
parameter space, coupled with the strong moisture transport,
suggests locally heavy rainfall is possible with isolated
several inch maxes.

The CAM consensus suggests a brief break toward midday, but
then the airmass recovers quickly into the afternoon as what is
now a short wave off the Baja coast reaches the MO Valley and
intensifies. Strong synoptic scale forcing should aid continued
low level theta-e advection into the warm sector and also what
is expected to be a line of storms forming along the associated
cold front, with more widespread weaker precip to the north and
west along the deformation zone. The precip should form into
discrete supercells initially shortly after onset with the
latest RAP suggesting uncapped 3000+ J/kg MLCAPEs with 50-60kts
of deep shear normal to the boundary. Thermodynamic questions do
remain however with recovery potentially delayed by the morning
convection, possibly resulting in the genesis region being
pushed farther east than depicted by hi res guidance. While
confidence in supercells is fairly high, confidence in tornadoes
is certainly there, but less. Examination of several CAM
soundings suggests a spectrum of possibilities. While all have
strong 500m shear, some seem more effective than others ranging
from alarming SRH and streamwise vorticity values and high
percentages of ingest, which could certainly be enhanced
depending on remnant outflow boundaries, to less favorable
crosswise SR ingest in broader SSW surface wind. It is curious
that various CAM 0-3km updraft helicity tracks during the
afternoon are not as ominous as one might think with a few
tracks but not numerous ones, unlike what was depicted on 26
Apr. Nevertheless, large hail and damaging wind expected, along
with the potential for tornadoes considering the overall severe
weather parameter space.

Any convection should exit by early evening leading to more
tranquil weather and seasonal temps for the next few days.
Albeit not as deep as our Tuesday system, our active pattern
will cycle another northern Plains trough passage Friday
bringing additional chances for showers and storms.
Deterministic GFS solutions aren't overly enthusiastic on
severe weather potential, with weaker instability and deep
shear. However 00Z 19 May CSU GEFS based machine learning
solutions do reflect at least some severe potential, especially
south. Other weaker waves will keep at least some precip chances
into the forecast through the weekend as well.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1144 PM CDT Sun May 19 2024

A line of showers and storms continues east of I-35 early this
morning and is expected to move out of the area over the next
few hours. However, a large cluster of additional showers and
storms are expected to lift north across the state after 06z,
which will allow for active weather to continue through much of
the morning. Periods of lower ceilings and reduced visibilities
from heavier rainfall with these storms may allow for MVFR
conditions at times. A drying period looks to occur by late
morning through the afternoon, before additional showers and
storms look to move into the area towards the evening. Specific
mention of timing and location of storms Monday evening remain
unclear and will largely depend on the previous storm evolution,
which will be monitored closely. Winds will gradually shift
south/southwesterly with slightly breezy winds through the
daylight hours.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...None.

&&

DISCUSSION...Small
AVIATION...Bury

Hazardous weather outlook, May 20, 4:21 AM CST, 39 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
521 AM CDT Mon May 20 2024

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-211100-
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-
521 AM CDT Mon May 20 2024

This Hazardous Weather Outlook is for much of central Iowa.

.DAY ONE...Today and tonight

Scattered thunderstorms are expected to develop over portions of
western Iowa during the early evening, with additional storms
moving in from the west during the early morning hours Tuesday.
Although a tornado cannot be ruled out, large hail, locally heavy
rains, and damaging winds are the most likely threats with the
stronger storms.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Thunderstorms from overnight are expected to linger into Tuesday
morning with damaging wind and locally heavy rains the primary
threats. Additional storms are expected to develop along a cold
front during the afternoon with tornadoes, damaging wind, locally
heavy rains, and large hail all possible. There is an Enhanced
Risk of severe weather Tuesday, three out of five on the scale.

Additional thunderstorm chances return at times Friday and
through the weekend. The severe weather potential for these days
will be better determined in the coming days.

.SPOTTER INFORMATION STATEMENT...

Spotters will likely be needed at times through Tuesday.

Small

In the hours before

Special weather statement, May 20, 12:26 AM CST, 4 hours 34 minutes before

Special Weather Statement
National Weather Service Des Moines IA
126 AM CDT Mon May 20 2024

IAZ060-061-073>075-083>086-095>097-200730-
Wapello IA-Appanoose IA-Marion IA-Jasper IA-Clarke IA-Lucas IA-
Polk IA-Wayne IA-Davis IA-Mahaska IA-Monroe IA-Warren IA-
126 AM CDT Mon May 20 2024

...STRONG THUNDERSTORMS WILL IMPACT LUCAS...MONROE...SOUTHEASTERN
POLK...WESTERN DAVIS...MARION...WESTERN WAPELLO...EASTERN WAYNE...
WESTERN MAHASKA...APPANOOSE...SOUTHERN JASPER...NORTHEASTERN CLARKE
AND EASTERN WARREN COUNTIES THROUGH 230 AM CDT...

At 125 AM CDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 12 miles west of Chariton
to 9 miles east of Corydon to near Novinger. Movement was north at 35
mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Indianola, Oskaloosa, Pella, Knoxville, Centerville, Chariton, Albia,
Bloomfield, Corydon, Carlisle, Monroe, Pleasantville, Melcher-Dallas,
Eddyville, Lake Sundown, Rathbun Lake, Knoxville Raceway, Lake Red
Rock, Sully, and Milo.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 200 AM CDT for
south central Iowa.

&&

LAT...LON 4067 9322 4104 9369 4159 9345 4158 9280
      4131 9258 4060 9238 4058 9315
TIME...MOT...LOC 0625Z 197DEG 32KT 4106 9354 4075 9314 4021 9274

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Dodson

The radar

The Des Moines radar (KDMX), 96 km away, was scanning. The volume nearest the first event began at 11:00 UTC.

Open the radar archive at this moment

Event by event

67 thunderstorm wind, 24 hail, 22 flash flood, 22 flood, 20 heavy rain, 1 funnel cloud. Local standard time, as filed.

Heavy Rain, Tama

When: May 20, 5:00 AM CST to May 21, 5:00 AM CST
Where: Tama County, 0.86 mi SE of Garwin
Reported by: COOP Observer
Coordinates: 42.090, -92.670

Coop observer reported 24 hr heavy rainfall of 3.05 inches.

Heavy Rain, Kossuth

When: May 20, 6:00 AM CST to May 21, 6:00 AM CST
Where: Kossuth County, 0.5 mi E of Algona
Reported by: Mesonet
Coordinates: 43.070, -94.220

Mesonet station ALGI4 reported 24hr heavy rainfall of 5.08 inches.

Heavy Rain, Kossuth

When: May 20, 6:00 AM CST to May 21, 6:00 AM CST
Where: Kossuth County, 2.05 mi NW of Irvington
Reported by: CoCoRaHS
Coordinates: 43.040, -94.230

CoCoRaHS station reported 24 hr heavy rainfall of 3.60 inches.

Heavy Rain, Tama

When: May 20, 6:00 AM CST to May 21, 6:00 AM CST
Where: Tama County, 2.76 mi N of Toledo
Reported by: COOP Observer
Coordinates: 42.040, -92.580

Coop observer reported 24 hr heavy rainfall of 3.33 inches.

Heavy Rain, Tama

When: May 20, 6:00 AM CST to May 21, 6:00 AM CST
Where: Tama County, 0.69 mi S of Traer
Reported by: COOP Observer
Coordinates: 42.190, -92.470

Coop observer reported 24 hr heavy rainfall of 3.09 inches.

Heavy Rain, Butler

When: May 20, 6:31 AM CST to May 21, 6:31 AM CST
Where: Butler County, 0.69 mi N of Parkersburg
Reported by: Mesonet
Coordinates: 42.580, -92.780

Mesonet FW8037 station reported 24 hr heavy rainfall of 3.57 inches.

Heavy Rain, Kossuth

When: May 20, 6:40 AM CST to May 21, 6:40 AM CST
Where: Kossuth County, 0.86 mi NW of Algona
Reported by: Mesonet
Coordinates: 43.080, -94.240

Mesonet station reported 24 hr heavy rainfall of 3.86 inches.

Heavy Rain, Kossuth

When: May 20, 6:44 AM CST to May 21, 6:44 AM CST
Where: Kossuth County, 0.5 mi W of Algona
Reported by: Mesonet
Coordinates: 43.070, -94.240

Mesonet station ALGIA reported 24 hr heavy rainfall of 3.53 inches.

Heavy Rain, Jasper

When: May 20, 6:56 AM CST to May 21, 6:56 AM CST
Where: Jasper County, 2.07 mi N of Newburg
Reported by: Mesonet
Coordinates: 41.850, -92.830

Personal weather station reported 24 hr heavy rainfall of 5.15 inches. Numerous other 3 to 5 inch amounts across northern Jasper County as well.

Heavy Rain, Polk

When: May 20, 6:58 AM CST to May 21, 6:58 AM CST
Where: Polk County, 2.14 mi NNE of Dodge Fld Arpt
Reported by: Trained Spotter
Coordinates: 41.710, -93.710

Trained spotter relayed 24 hr heavy rainfall of 3.50 inches.

Heavy Rain, Jasper

When: May 20, 7:12 AM CST to May 21, 7:12 AM CST
Where: Jasper County, 3.87 mi ESE of Newton Muni Arpt
Reported by: Trained Spotter
Coordinates: 41.660, -92.950

Trained spotter relayed 24 hr heavy rainfall of 4.25 inches.

Heavy Rain, Marshall

When: May 20, 7:13 AM CST to May 21, 7:13 AM CST
Where: Marshall County, 1.54 mi E of State Center
Reported by: Trained Spotter
Coordinates: 42.020, -93.140

Trained spotter relayed 24 hr heavy rainfall of 3.75 inches.

Heavy Rain, Audubon

When: May 20, 2:35 PM CST to May 21, 2:35 PM CST
Where: Audubon County, Audubon Arpt
Reported by: AWOS
Coordinates: 41.700, -94.920

Audubon Airport AWOS recorded 24 hr heavy rainfall of 3.08 inches.

Heavy Rain, Kossuth

When: May 20, 2:39 PM CST to May 21, 2:39 PM CST
Where: Kossuth County, 0.5 mi W of Algona
Reported by: Mesonet
Coordinates: 43.070, -94.240

Mesonet station ALGIA Algona reported 24 hr heavy rainfall of 4.02 inches.

Heavy Rain, Polk

When: May 20, 2:39 PM CST to May 21, 2:39 PM CST
Where: Polk County, 1.24 mi SE of Ankeny
Reported by: Mesonet
Coordinates: 41.720, -93.600

Mesonet station GW2554 Ankeny reported 24 hr heavy rainfall of 3.27 inches.

Hail, Kossuth

When: May 20, 7:50 PM CST
Where: Kossuth County, 0.85 mi NE of Titonka
Measured: 1 in hail
Reported by: Fire Department/Rescue
Coordinates: 43.240, -94.040

Local fire reported quarter sized hail. Time estimated from radar.

Hail, Palo Alto

When: May 20, 8:04 PM CST
Where: Palo Alto County, 0.51 mi W of Curlew
Measured: 0.88 in hail
Reported by: Emergency Manager
Coordinates: 42.980, -94.740

Emergency manager reported nickel sized hail. Time estimated from radar.

Hail, Palo Alto

When: May 20, 8:21 PM CST
Where: Palo Alto County, 0.69 mi N of Mallard
Measured: 1.75 in hail
Reported by: Public
Coordinates: 42.940, -94.680

Public reported slightly larger than golf ball size hail. Time estimated from radar.

Heavy Rain, Kossuth

When: May 20, 8:30 PM CST to 11:00 PM CST
Where: Kossuth County, 0.5 mi W of Algona
Reported by: Public
Coordinates: 43.070, -94.240

Algona Wastewater Plant reported 3.4 inches of heavy rain with rain still ongoing at the time of the report. Start time estimated from radar.

Heavy Rain, Guthrie

When: May 20, 9:30 PM CST to May 21, 8:45 AM CST
Where: Guthrie County, Guthrie Center
Reported by: Trained Spotter
Coordinates: 41.680, -94.500

Trained spotter reported heavy rainfall of 4.02 inches.

Heavy Rain, Cerro Gordo

When: May 20, 10:30 PM CST to May 21, 10:16 AM CST
Where: Cerro Gordo County, 1.01 mi E of Clear Lake Jct
Reported by: Public
Coordinates: 43.130, -93.210

Public reported storm total heavy rainfall of 3.40 inches thus far. Beginning time estimated from radar.

Flash Flood, Kossuth

When: May 20, 11:00 PM CST to May 21, 4:00 AM CST
Where: Kossuth County, Wesley to 0.38 mi N of Wesley
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 43.080, -94.000

Significant flash flooding beginning in Wesley.

Heavy Rain, Butler

When: May 21, 12:00 AM CST to 8:05 AM CST
Where: Butler County, 1.38 mi N of Kesley
Reported by: Public
Coordinates: 42.690, -92.920

Public reported heavy rainfall of 5.00 inches from overnight and this morning with rain still ongoing. Beginning time estimated from radar.

Heavy Rain, Polk

When: May 21, 12:15 AM CST to 8:58 AM CST
Where: Polk County, 0.86 mi NW of Saylorville
Reported by: Trained Spotter
Coordinates: 41.690, -93.640

Trained spotter reported storm-total rain, so far, of 4.50 inches. Also reported significant runoff in the house drainage easements. Beginning time estimated from radar.

Hail, Polk

When: May 21, 12:16 AM CST
Where: Polk County, 2.18 mi ENE of Ft Des Moines
Measured: 0.75 in hail
Reported by: Trained Spotter
Coordinates: 41.540, -93.590

Trained spotter reported penny sized hail.

Hail, Polk

When: May 21, 12:18 AM CST
Where: Polk County, 1.7 mi ENE of Ft Des Moines
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 41.540, -93.600

Trained spotter relayed picture of quarter sized hail.

Hail, Polk

When: May 21, 12:21 AM CST
Where: Polk County, 1.24 mi NE of Risingsun
Measured: 1 in hail
Reported by: Public
Coordinates: 41.590, -93.460

Public mping report of quarter sized hail.

Thunderstorm Wind, Audubon

When: May 21, 12:38 AM CST
Where: Audubon County, 0.86 mi NW of Audubon
Measured: 56 kt (64 mph) measured gust
Reported by: Mesonet
Coordinates: 41.730, -94.940

A personal weather station recorded a 64 mph wind gust in Audubon. Time taken from station observation report time.

Thunderstorm Wind, Audubon

When: May 21, 12:38 AM CST
Where: Audubon County, Audubon
Measured: 50 kt (58 mph) estimated gust
Reported by: Law Enforcement
Coordinates: 41.720, -94.930

Local law enforcement reported several tree branches down in the city of Audubon. Time estimated from radar.

Thunderstorm Wind, Audubon

When: May 21, 12:39 AM CST
Where: Audubon County, 0.52 mi E of Audubon
Measured: 52 kt (60 mph) estimated gust
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 41.720, -94.920

Emergency manager reported power lines down on the northeast side of Audubon. Time estimated from radar.

Thunderstorm Wind, Franklin

When: May 21, 12:50 AM CST
Where: Franklin County, 1.01 mi E of Beeds Lake Arpt
Measured: 61 kt (70 mph) estimated gust
Property damage: $75,000
Reported by: Emergency Manager
Coordinates: 42.770, -93.230

Emergency manager reported around a dozen power poles blown down along 170th st, west of Highway 65. This is a delayed report. Time and location estimated from radar.

Thunderstorm Wind, Black Hawk

When: May 21, 1:55 AM CST
Where: Black Hawk County, Cedar Falls
Measured: 52 kt (60 mph) estimated gust
Reported by: Social Media
Coordinates: 42.520, -92.450

Public reported, via social media, large branch down near UNI.

Thunderstorm Wind, Black Hawk

When: May 21, 2:06 AM CST
Where: Black Hawk County, 0.69 mi N of (Alo)waterloo Muni A
Measured: 61 kt (70 mph) measured gust
Reported by: ASOS
Coordinates: 42.560, -92.400

Waterloo Airport ASOS recorded a 70 mph wind gust.

Thunderstorm Wind, Black Hawk

When: May 21, 2:15 AM CST
Where: Black Hawk County, 2.63 mi WSW of Dunkerton Davis Arpt
Measured: 61 kt (70 mph) estimated gust
Property damage: $10,000
Reported by: COOP Observer
Coordinates: 42.610, -92.270

Coop observer reported damage to a grain bin, blown in. Time estimated from a recorded 70 mph wind gust at the Waterloo Airport at 305am CDT.

Flash Flood, Guthrie

When: May 21, 3:00 AM CST to 10:15 AM CST
Where: Guthrie County, 5.56 mi ESE of Fanslers to 7.5 mi ESE of Wichita
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.720, -94.370

Washed out gravel roads and road closures due to water over the road in the area.

Flash Flood, Guthrie

When: May 21, 3:00 AM CST to 10:15 AM CST
Where: Guthrie County, 2.14 mi NNW of Fanslers to 1.94 mi N of Fanslers
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.780, -94.480

Emergency manager reports 160th St in the Springbrook State Park area is closed due to water over the road.

Flash Flood, Boone

When: May 21, 4:00 AM CST to 10:00 AM CST
Where: Boone County, 2.99 mi SE of Moingona to 2.67 mi SE of Moingona
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 41.990, -93.888

Canyon road impassable due to water over the road.

Flash Flood, Jasper

When: May 21, 4:00 AM CST to 10:15 AM CST
Where: Jasper County, 0.52 mi E of Kellogg to 0.19 mi E of Kellogg
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.720, -92.910

Considerable flash flooding in Kellogg. Water flooding roads and buildings.

Flash Flood, Jasper

When: May 21, 4:00 AM CST to 10:15 AM CST
Where: Jasper County, 0.8 mi W of Baxter to 1.19 mi ESE of Baxter
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.819, -93.165

Considerable flash flooding in Baxter. Water flooding roads and buildings.

Flood, Kossuth

When: May 21, 4:10 AM CST to May 22, 7:00 AM CST
Where: Kossuth County, 0.88 mi N of Wesley to 0.32 mi N of Wesley
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 43.093, -94.002

Several blocks of flooded roads and homes in Wesley.

Flood, Hancock

When: May 21, 5:00 AM CST to May 22, 8:00 AM CST
Where: Hancock County, 1.47 mi SSE of Britt to 1.12 mi SE of Britt
Cause: Heavy Rain
Reported by: Public
Coordinates: 43.080, -93.810

Water on the road on 220th Street south Britt.

Flash Flood, Jasper

When: May 21, 5:00 AM CST to 10:00 AM CST
Where: Jasper County, 1.54 mi NNE of Newton to 1.77 mi NNE of Newton
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.719, -93.035

Considerable flooding ongoing in trailer park.

Flash Flood, Jasper

When: May 21, 6:00 AM CST to 10:15 AM CST
Where: Jasper County, 1.03 mi E of Kellogg to 0.71 mi ENE of Kellogg
Cause: Heavy Rain
Reported by: Public
Coordinates: 41.720, -92.900

Water over the road on IA 224 just north of Kellogg.

Flash Flood, Tama

When: May 21, 6:00 AM CST to 10:15 AM CST
Where: Tama County, 2.58 mi SW of Montour to 2.81 mi SSW of Montour
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.940, -92.750

Water flowing over B Ave south of 340th St due to flooding from Raven Creek.

Flash Flood, Tama

When: May 21, 6:00 AM CST to 10:15 AM CST
Where: Tama County, 2.07 mi S of Tama Arpt to 3.62 mi W of Irving
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 41.920, -92.580

Multiple reports of water over road in southern part of the county.

Flash Flood, Tama

When: May 21, 6:00 AM CST to 10:15 AM CST
Where: Tama County, 2.57 mi W of Tama to 2.41 mi WSW of Toledo
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 41.970, -92.630

Water running over roads and vehicles stranded in flood waters across portions of the Meskwaki Nation Settlement including Battleground Rd near the PowWow Grounds, Meskwaki Rd at Battleground Rd and G Ave South. Reported by the Meskwaki Nation Police Department via social media.

Thunderstorm Wind, Cass

When: May 21, 6:19 AM CST
Where: Cass County, 0.69 mi N of Lewis
Measured: 61 kt (70 mph) estimated gust
Property damage: $50,000
Reported by: Emergency Manager
Coordinates: 41.310, -95.080

Emergency manager reported numerous power poles and branches down throughout town. Time estimated from radar, this was a delayed report.

Thunderstorm Wind, Adair

When: May 21, 6:59 AM CST
Where: Adair County, 4.27 mi SSW of Canby
Measured: 69 kt (79 mph) measured gust
Reported by: Mesonet
Coordinates: 41.360, -94.600

A personal weather station measured a 79 mph wind gust.

Flash Flood, Tama

When: May 21, 7:00 AM CST to 10:15 AM CST
Where: Tama County, 2.76 mi N of Montour to 2.86 mi N of Montour
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 42.010, -92.720

C Ave north of US 30 closed due to flooding. Reported by Tama County Engineer via social media.

Flash Flood, Tama

When: May 21, 7:00 AM CST to 10:15 AM CST
Where: Tama County, 1.47 mi NNW of Traer to 2.17 mi N of Traer
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 42.220, -92.480

P Ave closed from 145th to 155th St due to flooding. Reported by Tama County Engineer via social media.

Flash Flood, Tama

When: May 21, 7:00 AM CST to 10:15 AM CST
Where: Tama County, 1.47 mi SSE of Montour to 0.43 mi S of Montour
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.950, -92.710

Hwy T47 closed south of Montour due to water flowing over the road.

Thunderstorm Wind, Adair

When: May 21, 7:20 AM CST
Where: Adair County, 1.48 mi NNE of Rosserdale
Measured: 61 kt (70 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 41.420, -94.410

Emergency manager reported estimated 70 mph winds and heavy rainfall.

Thunderstorm Wind, Adair

When: May 21, 7:30 AM CST
Where: Adair County, 5.18 mi NE of Howe
Measured: 61 kt (70 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 41.460, -94.320

Emergency manager reported estimated 70 mph wind gusts.

Thunderstorm Wind, Dallas

When: May 21, 7:42 AM CST
Where: Dallas County, 0.86 mi NE of Redfield
Measured: 61 kt (70 mph) estimated gust
Property damage: $5,000
Reported by: Emergency Manager
Coordinates: 41.590, -94.190

Emergency manager reported tree over powerline in Redfield.

Thunderstorm Wind, Dallas

When: May 21, 7:53 AM CST
Where: Dallas County, Adel
Measured: 56 kt (64 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 41.620, -94.020

Emergency manager reported large tree limbs down in Adel.

Thunderstorm Wind, Dallas

When: May 21, 8:05 AM CST
Where: Dallas County, 3.17 mi SSE of Hadden Hill
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 41.580, -93.800

Public reported large tree limb down. Time estimated from nearby KDSM wind gust observation.

Flash Flood, Hardin

When: May 21, 8:06 AM CST to 10:00 AM CST
Where: Hardin County, 5.6 mi W of Iowa Falls to 5.26 mi W of Iowa Falls
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.520, -93.380

Road closed due to water flowing over the road.

Hail, Dallas

When: May 21, 8:07 AM CST
Where: Dallas County, 2.07 mi S of Hadden Hill
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 41.590, -93.830

Trained spotter reported nickel to quarter sized hail and wind gusts estimated up to around 50 to 55 mph.

Thunderstorm Wind, Polk

When: May 21, 8:10 AM CST
Where: Polk County, 1.24 mi SE of Ashawa
Measured: 56 kt (64 mph) estimated gust
Property damage: $5,000
Reported by: Local Official
Coordinates: 41.570, -93.750

City official reported an ash tee blown over and across the street. Time estimated from radar.

Thunderstorm Wind, Polk

When: May 21, 8:15 AM CST
Where: Polk County, 0.52 mi W of Norwoodville
Measured: 52 kt (60 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 41.650, -93.580

Trained spotter reported estimated sustained winds of 45 mph and wind gusts to 60 mph. At the time, small branches broken.

Flash Flood, Jasper

When: May 21, 8:30 AM CST to 10:15 AM CST
Where: Jasper County, 2.06 mi E of Green Castle to 1.82 mi NNW of Goddard
Cause: Heavy Rain
Reported by: Trained Spotter
Coordinates: 41.750, -93.230

Water over gravel road intersection of N 51st Ave and W 100th St. N.

Flash Flood, Hardin

When: May 21, 8:31 AM CST to 10:00 AM CST
Where: Hardin County, 1.45 mi ESE of Iowa Falls to 1.42 mi ESE of Iowa Falls
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.514, -93.243

Water is covering 130th Street east of town.

Flash Flood, Grundy

When: May 21, 9:03 AM CST to 10:15 AM CST
Where: Grundy County, 5.04 mi NW of Wellsburg to 2.96 mi NNE of Fredsville
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.486, -92.983

An increasing number of county roads across the county are becoming impassable due to flash flooding.

Flash Flood, Butler

When: May 21, 9:16 AM CST to 10:15 AM CST
Where: Butler County, 1.72 mi E of Aplington to 1.84 mi E of Austinville
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 42.575, -92.847

IA 57 closed between Co Hwy T19 and T25 due to water over the road.

Flash Flood, Butler

When: May 21, 9:19 AM CST to 10:15 AM CST
Where: Butler County, 0.24 mi WSW of New Hartford to 0.38 mi ESE of New Hartford
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.568, -92.624

Main Street is covered with water.

Flash Flood, Grundy

When: May 21, 9:39 AM CST to 10:15 AM CST
Where: Grundy County, 4.87 mi NNW of Wellsburg to 5.1 mi NNW of Wellsburg
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.490, -92.970

Flooding on the roadway with field debris piling up.

Flash Flood, Jasper

When: May 21, 9:50 AM CST to 10:15 AM CST
Where: Jasper County, 0.65 mi SSE of Kellogg to 1.42 mi NE of Kellogg
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.711, -92.915

Sandbagging taking place due to rising waters.

Flood, Black Hawk

When: May 21, 9:54 AM CST to May 22, 8:00 AM CST
Where: Black Hawk County, 1.06 mi WNW of Cedar Falls to 1.38 mi E of Cedar Falls Isley Ar
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.523, -92.470

Sandbagging taking place due to rising waters.

Hail, Marion

When: May 21, 10:20 AM CST
Where: Marion County, 2.49 mi ESE of Pella Muni Arpt
Measured: 2 in hail
Reported by: Social Media
Coordinates: 41.380, -92.910

Public relayed, via social media, report of 2 inch hail.

Hail, Marion

When: May 21, 10:20 AM CST
Where: Marion County, 2.08 mi SE of Pella Muni Arpt
Measured: 2 in hail
Reported by: COOP Observer
Coordinates: 41.380, -92.920

Coop observer relayed 2 inch hail report.

Hail, Marion

When: May 21, 10:25 AM CST
Where: Marion County, 1.73 mi SE of Pella
Measured: 1 in hail
Reported by: Public
Coordinates: 41.400, -92.910

Public mping report of quarter sized hail.

Flood, Bremer

When: May 21, 10:35 AM CST to May 22, 7:00 AM CST
Where: Bremer County, 2.15 mi WSW of Klinger to 2.54 mi WSW of Klinger
Cause: Heavy Rain
Reported by: COOP Observer
Coordinates: 42.640, -92.260

Water is flowing over the road.

Flood, Butler

When: May 21, 10:35 AM CST to May 22, 8:00 PM CST
Where: Butler County, 3.93 mi W of Kesley to 3.36 mi SSW of Shell Rock
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.677, -92.997

County emergency management reports 17 road closures across southern Butler county due to water over roadways.

Flood, Marshall

When: May 21, 10:35 AM CST to May 22, 7:00 AM CST
Where: Marshall County, 1.74 mi ESE of La Moille to 2.13 mi ESE of La Moille
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 42.024, -92.997

The road is blocked due to flooding.

Hail, Mahaska

When: May 21, 10:39 AM CST
Where: Mahaska County, 0.52 mi E of Taintor
Measured: 1.75 in hail
Reported by: Fire Department/Rescue
Coordinates: 41.500, -92.740

Local fire reported golf ball sized hail in Taintor. Time estimated from radar.

Flood, Jasper

When: May 21, 10:40 AM CST to May 22, 5:00 AM CST
Where: Jasper County, 2.93 mi NW of Metz to 1.67 mi WNW of Metz
Cause: Heavy Rain
Reported by: Trained Spotter
Coordinates: 41.700, -93.170

Road closed due to two feet of water flowing over the road. Flood waters also entering homes and businesses.

Flood, Marshall

When: May 21, 10:49 AM CST to May 22, 5:00 AM CST
Where: Marshall County, 1.36 mi E of La Moille to 1.43 mi E of La Moille
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 42.031, -93.003

Iowa 300 closed at County Highway E41 dues to water over the road.

Flood, Black Hawk

When: May 21, 10:51 AM CST to May 22, 7:00 AM CST
Where: Black Hawk County, 1.38 mi N of Cedar Falls Jct to 1.74 mi NNE of Cedar Falls Jct
Cause: Heavy Rain
Reported by: Public
Coordinates: 42.450, -92.418

Report of street flooding and road closed with stranded vehicles.

Flood, Poweshiek

When: May 21, 11:08 AM CST to May 22, 5:00 AM CST
Where: Poweshiek County, 2.89 mi SSW of Carnforth to 2.4 mi NNW of Guernsey
Cause: Heavy Rain
Reported by: Public
Coordinates: 41.692, -92.353

Report of flooding via mping.

Flood, Butler

When: May 21, 11:21 AM CST to May 22, 6:00 PM CST
Where: Butler County, 1.71 mi ESE of Aplington to 1.34 mi ENE of Aplington
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.570, -92.849

Water covering the roadway.

Flood, Story

When: May 21, 11:40 AM CST to May 22, 5:00 AM CST
Where: Story County, 2.22 mi WNW of Collins to 2.41 mi NE of Collins
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.910, -93.341

Water over streets in town with fields draining of water. Many gravel roads flooding.

Flood, Butler

When: May 21, 11:49 AM CST to May 22, 6:00 PM CST
Where: Butler County, 1.37 mi NW of Parkersburg to 1 mi NE of Parkersburg
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 42.584, -92.799

Sandbagging is in progress.

Flood, Hancock

When: May 21, 12:18 PM CST to May 22, 5:00 AM CST
Where: Hancock County, 0.85 mi SW of Woden to 1.57 mi ESE of Woden
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 43.220, -93.930

Road closed due to water over the roads along with washouts on gravel roads.

Flood, Kossuth

When: May 21, 12:26 PM CST to May 22, 7:00 AM CST
Where: Kossuth County, 1.82 mi NNW of Wesley to 0.97 mi N of Wesley Arpt
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 43.103, -94.016

Several roads, homes, and buildings flooded. Many roads closed.

Flood, Kossuth

When: May 21, 12:27 PM CST to May 22, 7:00 AM CST
Where: Kossuth County, 3.05 mi NNE of Whittemore to 9.51 mi SE of Titonka
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 43.113, -94.407

Approximately 20 secondary roads closed in the county due to water over the road.

Flood, Jasper

When: May 21, 12:47 PM CST to May 22, 5:00 AM CST
Where: Jasper County, 2.67 mi SSE of Goddard to 2.85 mi SE of Goddard
Cause: Heavy Rain
Reported by: Public
Coordinates: 41.688, -93.192

Report via mping of river overflowing and cropland flooding.

Flood, Poweshiek

When: May 21, 1:28 PM CST to May 22, 5:00 AM CST
Where: Poweshiek County, 0.65 mi E of Carnforth to 2.02 mi WSW of Grinnell Arpt
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.731, -92.317

Approximately 10 secondary road closures due to water over the road in northern parts of the county.

Flood, Black Hawk

When: May 21, 1:44 PM CST to May 22, 5:00 AM CST
Where: Black Hawk County, 1.17 mi SSE of Dunkerton Davis Arpt to 1.72 mi SE of Dunkerton Davis Arpt
Cause: Heavy Rain
Reported by: Public
Coordinates: 42.604, -92.214

Report of river overflowing and cropland flooding from mping.

Hail, Cass

When: May 21, 2:10 PM CST
Where: Cass County, 3.61 mi SSE of Cumberland
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 41.220, -94.860

Trained spotter reported quarter sized hail.

Thunderstorm Wind, Carroll

When: May 21, 2:15 PM CST
Where: Carroll County, 0.51 mi W of Carroll Neu Arpt
Measured: 67 kt (77 mph) measured gust
Reported by: AWOS
Coordinates: 42.050, -94.790

Carroll Airport AWOS recorded a 77 mph wind gust.

Thunderstorm Wind, Carroll

When: May 21, 2:15 PM CST
Where: Carroll County, 0.86 mi SE of Carroll
Measured: 61 kt (70 mph) estimated gust
Property damage: $50,000
Reported by: Law Enforcement
Coordinates: 42.060, -94.870

Sheriff dispatch relayed wind and hail in Carroll, including trees and powerlines down.

Hail, Union

When: May 21, 2:42 PM CST
Where: Union County, 0.87 mi SE of Creston
Measured: 1.25 in hail
Reported by: Public
Coordinates: 41.060, -94.360

Public reported roughly half dollar sized hail in Creston. Time estimated from radar.

Funnel Cloud, Webster

When: May 21, 2:47 PM CST
Where: Webster County, 1.02 mi W of Callender Arpt
Reported by: Trained Spotter
Coordinates: 42.350, -94.340

Trained spotter reported a funnel cloud.

Hail, Kossuth

When: May 21, 2:50 PM CST
Where: Kossuth County, Algona
Measured: 0.88 in hail
Reported by: Emergency Manager
Coordinates: 43.070, -94.230

Emergency manager reported nickel sized hail.

Thunderstorm Wind, Webster

When: May 21, 2:50 PM CST
Where: Webster County, 0.69 mi N of Ft Dodge
Measured: 61 kt (70 mph) estimated gust
Property damage: $75,000
Reported by: Emergency Manager
Coordinates: 42.510, -94.180

Emergency manager reported trees down on power lines through town.

Thunderstorm Wind, Guthrie

When: May 21, 2:53 PM CST
Where: Guthrie County, 2.07 mi SW of Fanslers
Measured: 61 kt (70 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 41.730, -94.500

Trained spotter reported rain and strong winds resulting in broken and damaged trees.

Thunderstorm Wind, Kossuth

When: May 21, 2:55 PM CST
Where: Kossuth County, Algona Muni Arpt
Measured: 61 kt (70 mph) measured gust
Reported by: AWOS
Coordinates: 43.070, -94.270

Algona Airport AWOS recorded a 70 mph wind gust.

Hail, Madison

When: May 21, 3:07 PM CST
Where: Madison County, 0.69 mi N of Winterset
Measured: 1 in hail
Reported by: Broadcast Media
Coordinates: 41.340, -94.020

Local media reported quarter sized hail.

Flood, Marshall

When: May 21, 3:07 PM CST to May 22, 5:00 AM CST
Where: Marshall County, 1.21 mi NNE of Ferguson to 0.75 mi NNE of Marshalltown Arpt
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 41.946, -92.871

Several roads closed due to water over the roads. Several bridges impassable and a couple landslides due to the flooding.

Hail, Greene

When: May 21, 3:12 PM CST
Where: Greene County, 0.86 mi SE of Dana
Measured: 0.75 in hail
Reported by: Public
Coordinates: 42.110, -94.240

Public mping report of penny sized hail.

Hail, Dallas

When: May 21, 3:18 PM CST
Where: Dallas County, 0.69 mi S of Minburn
Measured: 0.88 in hail
Reported by: Amateur Radio
Coordinates: 41.760, -94.030

Amateur radio operator relayed nickel sized hail.

Hail, Clarke

When: May 21, 3:18 PM CST
Where: Clarke County, 1.73 mi SE of Murray
Measured: 0.75 in hail
Reported by: Public
Coordinates: 41.030, -93.950

Public mping report of penny sized hail.

Thunderstorm Wind, Clarke

When: May 21, 3:18 PM CST
Where: Clarke County, 0.87 mi SW of Murray
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 41.040, -93.980

Public mping report of 3 inch tree limbs broken, power pole damage.

Thunderstorm Wind, Hancock

When: May 21, 3:19 PM CST
Where: Hancock County, 1.66 mi ESE of Duncan
Measured: 61 kt (70 mph) estimated gust
Property damage: $100,000
Reported by: Emergency Manager
Coordinates: 43.090, -93.700

Emergency manager reported multiple large trees down, including some on buildings. This is a delayed report and time estimated from radar.

Thunderstorm Wind, Dallas

When: May 21, 3:25 PM CST
Where: Dallas County, 2.93 mi SE of Hadden Hill
Measured: 61 kt (70 mph) estimated gust
Reported by: Public
Coordinates: 41.590, -93.790

Public reported large trees down just south of Interstate 80 on county line between Dallas and Polk Counties. About 60th and Vista. Time estimated from radar.

Thunderstorm Wind, Polk

When: May 21, 3:29 PM CST
Where: Polk County, 0.86 mi SE of Urbandale
Measured: 61 kt (70 mph) estimated gust
Property damage: $75,000
Reported by: Public
Coordinates: 41.620, -93.710

Public reported tree down on house. Estimated 2 feet in diameter. Time estimated from radar.

Thunderstorm Wind, Warren

When: May 21, 3:29 PM CST
Where: Warren County, 1.25 mi ESE of St Marys
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 41.310, -93.710

Public mping report of 3 inch tree limbs broken, power pole damage.

Hail, Clarke

When: May 21, 3:31 PM CST
Where: Clarke County, 0.87 mi SW of Murray
Measured: 1 in hail
Reported by: Public
Coordinates: 41.040, -93.980

Public mping report of quarter sized hail.

Thunderstorm Wind, Warren

When: May 21, 3:32 PM CST
Where: Warren County, 1.25 mi ESE of Spring Hill
Measured: 61 kt (70 mph) estimated gust
Property damage: $50,000
Reported by: Public
Coordinates: 41.410, -93.650

Public reported large trees and power lines down.

Thunderstorm Wind, Polk

When: May 21, 3:33 PM CST
Where: Polk County, 1.24 mi NW of Dodge Fld Arpt
Measured: 56 kt (64 mph) estimated gust
Property damage: $5,000
Reported by: Broadcast Media
Coordinates: 41.690, -93.740

Local media relayed image of construction trailer flipped near the intersection of Peckham and 70th St. Time estimated from radar.

Thunderstorm Wind, Hamilton

When: May 21, 3:34 PM CST
Where: Hamilton County, 0.51 mi W of Blairsburg
Measured: 52 kt (60 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 42.480, -93.640

Emergency manager reported very strong winds and power outages.

Thunderstorm Wind, Hamilton

When: May 21, 3:37 PM CST
Where: Hamilton County, 1.02 mi W of Webster City
Measured: 52 kt (60 mph) estimated gust
Reported by: Broadcast Media
Coordinates: 42.470, -93.840

Local media reported power outages and tree limbs down.

Thunderstorm Wind, Worth

When: May 21, 3:42 PM CST
Where: Worth County, Hanlontown
Measured: 56 kt (64 mph) estimated gust
Property damage: $25,000
Reported by: Public
Coordinates: 43.280, -93.380

Public reported damage to grain bins and trees.

Hail, Warren

When: May 21, 3:43 PM CST
Where: Warren County, 4.18 mi S of St Marys
Measured: 0.75 in hail
Reported by: Public
Coordinates: 41.260, -93.720

Public mping report of penny sized hail.

Thunderstorm Wind, Polk

When: May 21, 3:48 PM CST
Where: Polk County, 1.03 mi W of Des Moines
Measured: 56 kt (64 mph) estimated gust
Property damage: $25,000
Reported by: Emergency Manager
Coordinates: 41.600, -93.640

Emergency management reported broken branches and some trees down in the area.

Thunderstorm Wind, Polk

When: May 21, 3:49 PM CST
Where: Polk County, 1.7 mi ENE of Windsor Hgts
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 41.610, -93.690

Public mping report of 3 inch tree limbs broken, power poles broken.

Thunderstorm Wind, Worth

When: May 21, 3:50 PM CST
Where: Worth County, 1.22 mi SW of Northwood
Measured: 61 kt (70 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 43.440, -93.240

Trained spotter reported downed trees along Highway 105, 1 mile west of Northwood.

Hail, Hardin

When: May 21, 3:51 PM CST
Where: Hardin County, 5.6 mi W of Iowa Falls
Measured: 1 in hail
Reported by: Public
Coordinates: 42.520, -93.380

Public mping report of quarter sized hail.

Thunderstorm Wind, Warren

When: May 21, 3:52 PM CST
Where: Warren County, 0.52 mi W of Clarkson
Measured: 61 kt (70 mph) estimated gust
Property damage: $75,000
Reported by: Emergency Manager
Coordinates: 41.500, -93.490

Emergency manager reported a tree on a house.

Thunderstorm Wind, Cerro Gordo

When: May 21, 3:52 PM CST
Where: Cerro Gordo County, Mason City
Measured: 61 kt (70 mph) estimated gust
Property damage: $150,000
Reported by: Emergency Manager
Coordinates: 43.150, -93.200

Emergency manager reported trees on multiple homes and power lines down.

Thunderstorm Wind, Cerro Gordo

When: May 21, 3:52 PM CST
Where: Cerro Gordo County, 4.41 mi SSW of Rockwell
Measured: 61 kt (70 mph) estimated gust
Reported by: Public
Coordinates: 42.920, -93.210

Public mping report of trees uprooted or snapped, roof damage.

Thunderstorm Wind, Jasper

When: May 21, 3:55 PM CST
Where: Jasper County, 0.52 mi W of Prairie City
Measured: 61 kt (70 mph) estimated gust
Property damage: $125,000
Reported by: Trained Spotter
Coordinates: 41.600, -93.240

Trained spotter reported widespread power lines and trees down and property damage in Prairie City. Estimated wind gusts of 65 to 70 mph and hail up to 1 inch in diameter. Time estimated from radar.

Thunderstorm Wind, Polk

When: May 21, 3:58 PM CST
Where: Polk County, 2.06 mi E of Ankeny
Measured: 52 kt (60 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 41.730, -93.580

Trained spotter reported large, 6 inch, diameter tree branch down.

Thunderstorm Wind, Jasper

When: May 21, 4:00 PM CST
Where: Jasper County, 0.52 mi W of Prairie City
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 41.600, -93.240

Public reported estimated 60 mph wind gusts and tree branches down.

Thunderstorm Wind, Polk

When: May 21, 4:04 PM CST
Where: Polk County, Johnston
Measured: 61 kt (70 mph) estimated gust
Reported by: Public
Coordinates: 41.670, -93.700

Public mping report of trees uprooted or snapped, roof damage.

Thunderstorm Wind, Hardin

When: May 21, 4:06 PM CST
Where: Hardin County, 0.69 mi N of Hubbard
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 42.310, -93.300

Public reported wind gusts to around 60 mph and at least portions of town without power.

Thunderstorm Wind, Polk

When: May 21, 4:07 PM CST
Where: Polk County, Johnston
Measured: 56 kt (64 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 41.670, -93.700

Trained spotter reported a pine tree down, estimated 6 to 8 inches diameter, along with other tree damage.

Thunderstorm Wind, Jasper

When: May 21, 4:09 PM CST
Where: Jasper County, 0.69 mi S of Newton Muni Arpt
Measured: 62 kt (71 mph) measured gust
Reported by: AWOS
Coordinates: 41.670, -93.020

Newton Airport AWOS recorded a 71 mph wind gust.

Thunderstorm Wind, Polk

When: May 21, 4:09 PM CST
Where: Polk County, 0.86 mi SW of Dodge Fld Arpt
Measured: 61 kt (70 mph) estimated gust
Reported by: Public
Coordinates: 41.670, -93.730

Uprooted trees, generally shallow rooted, seen around Beaver Dr.

Thunderstorm Wind, Polk

When: May 21, 4:09 PM CST
Where: Polk County, 0.86 mi NW of Clive
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 41.640, -93.790

Public mping report of 3 inch tree limbs broken, power poles damaged.

Thunderstorm Wind, Franklin

When: May 21, 4:10 PM CST
Where: Franklin County, 0.69 mi S of Hampton Muni Arpt
Measured: 56 kt (64 mph) measured gust
Reported by: AWOS
Coordinates: 42.720, -93.230

Hampton airport AWOS recorded a 64 mph wind gust.

Thunderstorm Wind, Jasper

When: May 21, 4:12 PM CST
Where: Jasper County, 0.69 mi S of Newton Muni Arpt
Measured: 62 kt (71 mph) measured gust
Reported by: AWOS
Coordinates: 41.670, -93.020

Newton Airport AWOS recorded a 71 mph wind gust.

Thunderstorm Wind, Hardin

When: May 21, 4:13 PM CST
Where: Hardin County, 2.04 mi W of Lawn Hills
Measured: 52 kt (60 mph) estimated gust
Property damage: $15,000
Reported by: Emergency Manager
Coordinates: 42.300, -93.210

Emergency manager reported damage to farm outbuildings east of Hubbard. Time estimated from radar.

Thunderstorm Wind, Jasper

When: May 21, 4:23 PM CST
Where: Jasper County, 3.45 mi NE of Newburg
Measured: 52 kt (60 mph) estimated gust
Property damage: $15,000
Reported by: Emergency Manager
Coordinates: 41.860, -92.790

Emergency manager reported damage to farm outbuildings near Gilman. Time estimated from radar.

Thunderstorm Wind, Marshall

When: May 21, 4:26 PM CST
Where: Marshall County, 0.69 mi S of Marshalltown Arpt
Measured: 56 kt (64 mph) measured gust
Reported by: ASOS
Coordinates: 42.110, -92.920

Marshalltown Airport ASOS recorded a 64 mph wind gust.

Thunderstorm Wind, Butler

When: May 21, 4:27 PM CST
Where: Butler County, 1.23 mi SE of Aredale
Measured: 52 kt (60 mph) estimated gust
Property damage: $15,000
Reported by: Emergency Manager
Coordinates: 42.820, -92.980

Emergency manager reported damage to farmstead outbuildings near the intersection of Clay Ave and 160th St near Dumont. Damage included an outbuilding being blown over. Time estimated from radar.

Thunderstorm Wind, Dallas

When: May 21, 4:30 PM CST
Where: Dallas County, 1.7 mi ENE of Shuler Mine
Measured: 56 kt (64 mph) estimated gust
Property damage: $15,000
Reported by: Trained Spotter
Coordinates: 41.640, -93.850

Trained spotter reported 4 to 5 inch diameter tree branches down and power lines snapped.

Hail, Monroe

When: May 21, 4:35 PM CST
Where: Monroe County, 1.56 mi W of Albia Muni Arpt
Measured: 1 in hail
Reported by: Emergency Manager
Coordinates: 41.000, -92.800

Emergency manager reported quarter sized hail.

Thunderstorm Wind, Monroe

When: May 21, 4:35 PM CST
Where: Monroe County, 1.56 mi W of Albia Muni Arpt
Measured: 52 kt (60 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 41.000, -92.800

Emergency manager reported tree damage with the gust front. Time estimated from radar.

Thunderstorm Wind, Butler

When: May 21, 4:37 PM CST
Where: Butler County, 0.86 mi SE of Kesley
Measured: 56 kt (64 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 42.660, -92.910

Emergency manager reported a large tree uprooted in Kesley. Time estimated from radar.

Hail, Monroe

When: May 21, 4:38 PM CST
Where: Monroe County, 1.71 mi ENE of Melrose
Measured: 1.5 in hail
Reported by: Trained Spotter
Coordinates: 40.980, -93.000

Trained spotter reported larger than half dollar size hail.

Thunderstorm Wind, Tama

When: May 21, 4:38 PM CST
Where: Tama County, 3.66 mi W of Toledo
Measured: 61 kt (70 mph) estimated gust
Reported by: Law Enforcement
Coordinates: 41.990, -92.650

Local law enforcement reported trees down in Meskwaki area.

Thunderstorm Wind, Butler

When: May 21, 4:40 PM CST
Where: Butler County, 1.01 mi W of Allison
Measured: 61 kt (70 mph) estimated gust
Property damage: $15,000
Reported by: Emergency Manager
Coordinates: 42.750, -92.800

Emergency manager reported trees and some powerlines down within the city of Allison. Time estimated from radar.

Hail, Marion

When: May 21, 4:41 PM CST
Where: Marion County, 0.86 mi NW of Pella Muni Arpt
Measured: 1 in hail
Reported by: Public
Coordinates: 41.410, -92.960

Public mping report of quarter sized hail.

Thunderstorm Wind, Franklin

When: May 21, 4:42 PM CST
Where: Franklin County, 0.51 mi W of Hampton
Measured: 56 kt (64 mph) estimated gust
Reported by: Public
Coordinates: 42.750, -93.210

Public mping report of trees uprooted or snapped, roof damage.

Thunderstorm Wind, Butler

When: May 21, 4:46 PM CST
Where: Butler County, Greene
Measured: 61 kt (70 mph) estimated gust
Property damage: $15,000
Reported by: Emergency Manager
Coordinates: 42.900, -92.800

Emergency manager reported some trees and powerlines down within the city of Greene. Time estimated from radar.

Thunderstorm Wind, Butler

When: May 21, 4:46 PM CST
Where: Butler County, 1.67 mi WSW of Greene
Measured: 61 kt (70 mph) estimated gust
Property damage: $50,000
Reported by: Emergency Manager
Coordinates: 42.890, -92.830

Emergency manager reported trees blown onto a house west of Greene near the intersection of 110th st and Keystone Ave. Time estimated from radar.

Thunderstorm Wind, Tama

When: May 21, 4:49 PM CST
Where: Tama County, 0.69 mi S of Traer Muni Arpt
Measured: 56 kt (64 mph) estimated gust
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 42.190, -92.450

Emergency manager reported power lines down near the intersection of Highway 8 and QQ Ave near Traer. Time estimated from radar.

Thunderstorm Wind, Tama

When: May 21, 4:50 PM CST
Where: Tama County, 0.86 mi SW of Traer Muni Arpt
Measured: 56 kt (64 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 42.190, -92.460

Emergency manager reported estimated 60 to 70 mph wind gusts along with pea sized hail.

Thunderstorm Wind, Jasper

When: May 21, 4:55 PM CST
Where: Jasper County, Sully
Measured: 56 kt (64 mph) estimated gust
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 41.580, -92.850

Emergency manager reported power poles leaning in the town of Sully. Time estimated from radar.

Thunderstorm Wind, Jasper

When: May 21, 4:56 PM CST
Where: Jasper County, 0.52 mi E of Sully
Measured: 52 kt (60 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 41.580, -92.840

Trained spotter reported estimated 60 mph wind gusts. Taken from mping.

Flood, Franklin

When: May 21, 4:57 PM CST to May 22, 5:00 AM CST
Where: Franklin County, 0.69 mi NNE of Hampton Muni Arpt to 1.05 mi NE of Hampton Muni Arpt
Cause: Heavy Rain
Reported by: Public
Coordinates: 42.739, -93.224

Report of flooding from mping.

Thunderstorm Wind, Story

When: May 21, 4:58 PM CST
Where: Story County, 1.69 mi ENE of Cambridge
Measured: 61 kt (70 mph) estimated gust
Property damage: $25,000
Reported by: Trained Spotter
Coordinates: 41.910, -93.500

Spotter reported power lines down, still live, and trees down and other debris.

Thunderstorm Wind, Black Hawk

When: May 21, 5:01 PM CST
Where: Black Hawk County, 0.69 mi N of (Alo)waterloo Muni A
Measured: 59 kt (68 mph) measured gust
Reported by: ASOS
Coordinates: 42.560, -92.400

Marshalltown Airport ASOS recorded 68 mph wind gust.

Thunderstorm Wind, Black Hawk

When: May 21, 5:41 PM CST
Where: Black Hawk County, 2.31 mi NNE of Cedar Falls Jct
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 42.460, -92.400

Public mping report of 3 inch tree limbs broken, power poles damaged.

Flood, Butler

When: May 22, 12:54 AM CST to 5:00 AM CST
Where: Butler County, 1.23 mi NW of Parkersburg to 1.66 mi W of Parkersburg
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 42.580, -92.800

Iowa DOT reports IA 57 east bound at IA 14 closed due to water over the road.

What these are

Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
Funnel Cloud: A rotating column of cloud extending from a thunderstorm that did not reach the ground.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Iowa in 2024 Every state in 2024 This day in weather history Warnings in Iowa, May 2024

Sources

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: 1180850, 1180842, 1180845, 1180848, 1180849, 1180846, 1180844, 1180847, 1180851, 1180852, 1180853, 1180854, 1180867, 1180871, 1180876, 1180816, 1180817, 1180818, 1180841, 1180856, 1180864, 1183845, 1180855, 1180858, 1180819, 1180820, 1180821, 1180877, 1180893, 1180894, 1180898, 1180895, 1180878, 1180900, 1183260, 1183263, 1183243, 1183312, 1183313, 1183305, and more.