Flash Flooding and Hail in Iowa, June 16, 2004

Name: Flash Flooding and Hail in Iowa, June 16, 2004
Start: 2004-06-16T11:56
End: 2004-06-16T18:45
Location: Iowa

June 16, 2004 · NWS DMX · 17 events in 10 counties and zones

Where it happened

Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. 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: $272,000
Crop damage: $40,000
Events: 17

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.

A tropical airmass was in place over Iowa as a weak cold front moved southeast into the state. At the same time, a tropical feature lifted north across Texas into Oklahoma and fed moisture into the state. Dew points south of the front rose into the mid 70s by the late morning hours. Precipitable water values were in the one and one half to two inch range with CAPE values across the state ranging from 1500 J/kg along the front to 3500 J/kg a ways ahead of the front. Zero to 3 km CAPE values were between 100 and 175 J/kg. During the mid morning hours thunderstorms fired up in northwest Iowa as the MCV from the previous nights MCS moved northeast into western Iowa. The thunderstorms expanded through the morning into the afternoon hours. Most of the storms were tropical in nature, but did produce pea to marble size hail at many locations. There were a few reports of hail up to an inch in diameter. As the event unfolded, a few of the storms produced downburst winds. Wind gusts were limited to around 60 MPH. Two barns were blown down in Webster County by the high winds. The main event was the heavy tropical rainfall. A band of heavy rainfall extended from west central into north central Iowa. A band of two to four inch rainfall extended from near Sac City toward Fort Dodge into the Mason City area. Locally heavier amounts of 4 to 5 inches were received. Numerous roads were flooded in Webster County with a main bridge into Fort Dodge close due to high water. Fifteen roads were flooded in Cerro Gordo County. In Calhoun County, U.S. Highway 20 east of Rockwell City was under water with numerous county roads flooded. Heavy rainfall in Des Moines caused flash flooding with water flowing over 2 feet deep over U.S. Highway 6 in town. Nearly two inches of rain fell within a 30 minute period in the area to produce the flash flood.

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 Jun 15, 8:15 PM CST, 15 hours 41 minutes earlier.

Area forecast discussion, Jun 15, 8:15 PM CST, 15 hours 41 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
915 PM CDT TUE JUN 15 2004

.SHORT TERM...TNGT
00Z SFC MAP SHOWING CDFNT OVR SE SD.  TSTMS DEVELOPED NEAR BOUNDARY
OVR SERN SD AND MN.  MORE WDSPRD CONVECTION OVER NEBRASKA ALONG
BOUNDARY.  AMS RMNS UNSTABLE OVER WRN IA ATTM.  A FEW SHOWERS OVR SE
IN TROPICAL AMS LIFTING NE.

CONCERN TONIGHT IS TSTMS OVR FA.  DEEP CONVECTION AND AREA OF
PRIMARY CONCERN FOR HEAVY RAIN/SEVERE WEATHER SHOULD REMAIN FOCUSED
TO THE WEST OF IA ON THE NOSE OF LOW-LVL JET.  CDFNT SHUD PUSH INTO
NW LATE TONIGHT.  IA APPEARS TO BE TOO FAR SOUTH TO BENEFIT FM
DYNAMICS ASSOCIATED WITH TAIL OF S/WV TROF OVER SRN CANADA.  TROF
SHOULD BE STRONG ENOUGH TO PUSH BOUNDARY INTO IA OVERNIGHT.  LOW-LVL
JET SUPPORT NOT OVERLY GOOD EITHER FOR CONTINUED CONVECTION (20KTS
OR LESS). WILL KEEP POPS IN NW FA DURG OVERNIGHT HOURS AND DROP TO
THE SOUTHEAST.

NO CHANGES TO FCST ON WEDNESDAY AND WILL KEEP WATCH GOING.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH WED.

&&

JOHNSON

Hazardous weather outlook, Jun 16, 4:55 AM CST, 7 hours 1 minute before

HAZARDOUS WEATHER OUTLOOK...CORRECTION
NATIONAL WEATHER SERVICE DES MOINES IA
555 AM CDT WED JUN 16 2004

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-171059-
ADAIR-ADAMS-APPANOOSE-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-
CARROLL-CASS-CERRO GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-DECATUR-EMMET-
FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-
JASPER-KOSSUTH-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-
PALO ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR-
UNION-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT-
500 AM CDT WED JUN 16 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ALL OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT
A THREAT OF HEAVY RAINFALL AND FLASH FLOODING EXISTS THIS AFTERNOON
AND TONIGHT.  SCATTERED THUNDERSTORMS WILL DEVELOP BEFORE NOON IN
WESTERN AND CENTRAL IOWA...AND SPREAD NORTHEAST THROUGH THE
AFTERNOON.  OTHER STORMS WILL DEVELOP ALONG A COLD FRONT DROPPING
INTO NORTHERN IOWA.  RAINFALL RATES OF 1 TO 3 INCHES PER HOUR...SLOW
MOVEMENT AND TRAINING OF STORMS COULD LEAD TO EXCESSIVE RAINFALL IN
A SHORT PERIOD OF TIME.

THERE IS ALSO A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON...INCLUDING A THREAT OF BRIEF ISOLATED TORNADOES.
CONDITIONS ARE FAVORABLE FOR FAST DEVELOPING LANDSPOUT AND MINI-
SUPERCELL TORNADOES.  HAIL IS A LESSOR THREAT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH MONDAY
ANOTHER PERIOD OF THUNDERSTORMS WITH POTENTIALLY HEAVY RAIN WILL
OCCUR ON THURSDAY...BUT THE RISK OF SEVERE WEATHER IS QUITE LOW.

LOOKING FURTHER AHEAD...THUNDERSTORMS ARE AGAIN POSSIBLE SATURDAY
AND TUESDAY...BOTH WITH SLIGHT RISKS OF SEVERE WEATHER AND HEAVY
RAINFALL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE TODAY FOR SEVERE WEATHER...AND FOR
TONIGHT AND THURSDAY PRIMARILY TO REPORT FLOODING OR HEAVY RAIN
TOTALS.  SPOTTERS MAY AGAIN BE NEEDED AGAIN SATURDAY AND
TUESDAY.

KULA

The radar

The Des Moines radar (KDMX), 126 km away, was scanning. The volume nearest the first event began at 17:56 UTC.

Open the radar archive at this moment

Event by event

6 hail, 6 thunderstorm wind, 5 flash flood. Local standard time, as filed.

Hail, Sac

When: June 16, 11:56 AM CST
Where: Sac County, 1 mi E of Lake View
Measured: 0.75 in hail
Reported by: LAW ENFORCEMENT
Coordinates: 42.317, -95.033

Dime size hail

Flash Flood, Polk

When: June 16, 12:00 PM CST to 1:30 PM CST
Where: Polk County, Des Moines
Measured: 50
Reported by: NEWSPAPER
Coordinates: 41.686, -93.573 (the zone’s center; the record gives no point)

Hail, Polk

When: June 16, 12:20 PM CST
Where: Polk County, Clive
Measured: 0.75 in hail
Reported by: LAW ENFORCEMENT
Coordinates: 41.633, -93.783

Dime size hail

Hail, Sac

When: June 16, 12:23 PM CST
Where: Sac County, Auburn
Measured: 1 in hail
Property damage: $2,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.250, -94.883

Hail, Polk

When: June 16, 12:29 PM CST
Where: Polk County, Urbandale
Measured: 0.75 in hail
Reported by: LAW ENFORCEMENT
Coordinates: 41.633, -93.717

Dime size hail

Flash Flood, Calhoun

When: June 16, 12:30 PM CST to 3:30 PM CST
Where: Calhoun County, Countywide
Property damage: $50,000
Crop damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.385, -94.640 (the zone’s center; the record gives no point)

Thunderstorm Wind, Webster

When: June 16, 12:40 PM CST
Where: Webster County, 4 mi S of Barnum
Measured: 61 kt (70 mph) estimated gust
Property damage: $15,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.467, -94.533

Flash Flood, Sac

When: June 16, 12:45 PM CST to 2:15 PM CST
Where: Sac County, Countywide
Property damage: $50,000
Crop damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.386, -95.105 (the zone’s center; the record gives no point)

Thunderstorm Wind, Calhoun

When: June 16, 12:50 PM CST
Where: Calhoun County, 5 mi E of Lohrville
Measured: 52 kt (60 mph) estimated gust
Property damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.267, -94.450

Thunderstorm Wind, Boone

When: June 16, 1:00 PM CST
Where: Boone County, 2 mi NW of Madrid
Measured: 61 kt (70 mph) estimated gust
Property damage: $15,000
Reported by: EMERGENCY MANAGER
Coordinates: 41.900, -93.883

Thunderstorm Wind, Webster

When: June 16, 1:20 PM CST
Where: Webster County, 4 mi W of Ft Dodge
Measured: 52 kt (60 mph) estimated gust
Property damage: $2,000
Reported by: TRAINED SPOTTER
Coordinates: 42.500, -94.267

Flash Flood, Webster

When: June 16, 1:30 PM CST to 4:30 PM CST
Where: Webster County, North Portion
Property damage: $75,000
Crop damage: $10,000
Reported by: EMERGENCY MANAGER
Coordinates: 42.428, -94.182 (the zone’s center; the record gives no point)

Thunderstorm Wind, Wright

When: June 16, 2:20 PM CST
Where: Wright County, Clarion
Measured: 52 kt (60 mph) estimated gust
Property damage: $5,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.733, -93.733

Thunderstorm Wind, Franklin

When: June 16, 2:41 PM CST
Where: Franklin County, Latimer
Measured: 53 kt (61 mph) measured gust
Property damage: $3,000
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 42.767, -93.367

Flash Flood, Cerro Gordo

When: June 16, 3:30 PM CST to 6:45 PM CST
Where: Cerro Gordo County, Countywide
Property damage: $50,000
Crop damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 43.082, -93.261 (the zone’s center; the record gives no point)

Hail, Jasper

When: June 16, 3:45 PM CST
Where: Jasper County, 5 mi W of Newton
Measured: 0.75 in hail
Reported by: LAW ENFORCEMENT
Coordinates: 41.700, -93.150

Dime size hail

Hail, Decatur

When: June 16, 4:40 PM CST
Where: Decatur County, Leon
Measured: 0.75 in hail
Reported by: LAW ENFORCEMENT
Coordinates: 40.733, -93.733

Dime size hail

What these are

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.

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

The same day elsewhere

Every storm in Iowa in 2004 Every state in 2004 This day in weather history Warnings in Iowa, June 2004

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: 5405477, 5405480, 5405475, 5405464, 5405476, 5405467, 5405465, 5405468, 5405466, 5405469, 5405470, 5405471, 5405472, 5405473, 5405474, 5405478, 5405479.