Tornadoes and Flash Flooding in Iowa, May 29 to 30, 2008

Name: Tornadoes and Flash Flooding in Iowa, May 29 to 30, 2008
Start: 2008-05-29T11:00
End: 2008-05-30T23:49
Location: Iowa

May 29 to 30, 2008 · NWS DMX · 70 events in 22 counties and zones

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: 11
Property damage: $2.8 million
Crop damage: $190,000
Events: 70

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 very unstable airmass moved into Iowa during the day on the 29th as a warm front lifted north into the state during the afternoon. Low pressure approached from the west, along with a cold front so that the triple point was near the western Iowa, eastern Nebraska area by late afternoon. Thunderstorms erupted quickly during the late afternoon and evening hours in the unstable airmass. By evening, the low level jet was in the 40 to 60 kt range, feeding moisture into the state and pushing precipitable water values to around 200% of normal, in the 1.5 to 1.8 inch range. MUCAPE reached 3000 to 3500 J/kg over western Iowa, with lifted indices in the -6 to -10 C. range. The freezing level was quite high, limiting the hail size somewhat with this event, at 14,300 feet. The available CAPE in the -10 to -30 C. layer of the atmosphere was in the 300 to 500 J/kg range. The DCAPE was between 800 and 1000 J/kg. The environment was highly sheared with 50 to 65 kts of shear available during the event. The LCL was also quite low, in the 750 to 1250 meter range. Thunderstorms erupted over western Iowa stretching into north central Iowa first. It did not take long for the storms to become severe with hail and high winds. Most of the hail reported was in the pea to marble size, with the larger stones in the nickel to quarter size range. The primary mode of severe weather was high winds and several tornadoes. The secondary, but significant threat, was heavy rainfall. A band of 3 to 5 inches of rain fell between U.S. Highway 30 and U.S. Highway 20 during the event. The heaviest rainfall total was in Greene County at Jefferson, with 5.90 inches. Tornadoes began to touch down in western Iowa in Crawford County with two brief touchdowns. One was west of Dow City, causing roof and shingle damage to a farmhouse there. The next was east of Denison where a barn roof was removed and a trailer house was destroyed. A tornado in Carroll County caused damage to 3 farmsteads southeast of Templeton. A machine shed was completely destroyed and numerous other buildings sustained damage. Trees also had substantial damage. Two tornadoes touched down in Calhoun County. One near Farnhamville, tore the roof off of a home and downed power lines. The second caused damage to trees, outbuildings, and power lines on four farmsteads. Farther south, a brief touchdown was reported in Dallas County in open fields west of Minburn. Another tornado touched down in Dallas County later on, west of Adel, and was on the ground for about 4 miles. A more substantial tornado touched down near Murray in Clarke County with one reported on the ground for about 9 miles. As the storms moved east, another tornado was on the ground for over 10 miles in Warren and Marion Counties. The most significant tornado occurred in Marion and Mahaska Counties where an EF2 tornado was on the ground for about 18 miles. Several homes were damaged along its path, two mobile homes were destroyed, and considerable damage was done to trees in the area. Up to 10 people were injured with this tornado, mainly in Attica. The official damage count from this tornado included 5 homes destroyed, 15 with major damage, and another 25 with minor damage. Many of the storms produced high winds with several reports of winds in the 65 to 75 MPH range. Considerable tree damage was reported and some structural damage, mainly outbuildings and shingle damage. Two cars were blown off of the road east of Manning by the high winds. Building debris was blown onto Highway D60 near Gowrie, causing a brief closure. High winds in Butler County blew down a machine shed and barn southwest of Aplington, very near to where an EF5 tornado struck just days before. Extensive damage was done to a farmstead there with some damage done to the house itself as well. Lightning struck a man in Carroll. The lightning bolt hit his driveway, blowing out a chunk of concrete out of the driveway and also injured the man. He was taken to hospital, treated, and released with minor injuries. Flooding became a significant issue after the heavy rainfall of the previous few days. Extensive river flooding occurred across the central third of the state. Record crests were recorded on the Iowa River at Marshalltown.

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 28, 10:53 PM CST, 12 hours 7 minutes earlier.

Area forecast discussion, May 28, 10:53 PM CST, 12 hours 7 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1153 PM CDT WED MAY 28 2008

...UPDATED AVIATION DISCUSSION...

.SHORT TERM...TONIGHT THROUGH FRI NIGHT
SFC-850 MB RIDGE TO THE EAST OF THE UPPER MISSISSIPPI RIVER VALLEY
HAS KEPT A COOLER AND DRIER THAN NORMAL AIRMASS ACROSS MUCH OF THE
CWA. THE SFC RIDGE WILL SLOWLY GIVE WAY EASTWARD WITH TIME...WHILE A
SHORTWAVE OVER THE CENTRAL ROCKIES IS SPREADING RAPIDLY INTO THE
CENTRAL PLAINS TONIGHT. PLENTY OF SIMILARITIES IN THE RUC/NAM/GFS
BRINGING INTENSE 850 MOISTURE TRANSPORT AND THETA-E ADVECTION ACROSS
CENTRAL/EASTERN NEBRASKA OVERNIGHT...AND HAVE GONE WITH CATEGORICAL
HIGH POPS IN THE NORTHWEST AFTER 06Z. TEMPS WILL BE HARD WITH ON
GOING T-ADVECTION. POTENTIAL FOR HEAVY RAIN RATES IN THIS ZONE...
HOWEVER LIMITED INITIAL SEVERE THREAT AS SHOULD BE MAINLY ELEVATED
WITH LACK OF SIGNIFICANT CAPE.

DOMESTIC MODELS ARE PAINTING SIMILAR PICTURE FOR CONVECTIVE TRENDS
THU INTO FRI AND COULD VERY WELL TURN INTO ANOTHER SIGNIFICANT
EVENT.  EXPECT OVERNIGHT WARM ADVECTION MCS TO LINGER INTO FRI OVER
AT LEAST NRN HALF OF IA...PUSHING INTO NERN SECTIONS LATE IN THE
DAY.  ANY BREAK WILL LIKELY NOT LAST TOO LONG HOWEVER.  NAM/GFS
MLCAPE/CIN TRENDS BOTH INDICATE DEVELOPMENT ALONG NE FRONTAL
BOUNDARY NOSING INTO SIOUXLAND AREA.  SEE NO REASON WHY CIN WILL NOT
ERODE CONSIDERING ACTIVE SWLY FLOW AND PROXIMITY TO JET WITH COMPLEX
FIRING TO OUR WEST IN 2000-3500 J/KG MLCAPE AXIS THEN MOVING QUICKLY
INTO IA AT 30-40KTS...MAYBE EVEN TOWARD 50KTS.  THIS INSTABILITY
COMBINED WITH PLENTY OF SHALLOW AND DEEP SHEAR MAKES ALL STORM MODES
POSSIBLE /LARGE HAIL...DAMAGING WIND...AND TORNADOES/.  ALTHOUGH
INSTABILITY DIMINISHES SOMEWHAT OVERNIGHT...CIN STILL RELATIVELY LOW
WITH PERSISTENT AFOREMENTIONED SHALLOW AND DEEP SHEAR SO WOULD NOT
BE SURPRISED TO HAVE SVR AND EVEN TORNADO THREAT CONTINUE LONGER
THAN TYPICAL DIURNAL PEAK.  HEAVY RAINS AND FLOODING POSSIBLE AS
WELL WITH DETAILS NOTED IN HYDROLOGY SECTION BELOW.

MCS SHOULD LINGER INTO FRI BUT DISSIPATE TOWARD MIDDAY AS LOW LEVEL
JET VEERS.  FRONTAL BOUNDARY WILL STILL LAG HOWEVER AND BE ORIENTED
SW-NE ACROSS HEART OF IA DURING PEAK HEATING.  NAM/GFS AGAIN
DIMINISH CIN AND REALLY BOOST MLCAPE BY AFTERNOON INTO 3000-4000
J/KG RANGE...WHICH MAKES SENSE CONSIDERING MOISTURE HAS ANOTHER DAY
TO ESTABLISH ITSELF IN THE WARM SECTOR WITH MOIST SOILS IN PLACE.
ANOTHER ROUND OF CONVECTION WILL LIKELY DEVELOP SERN HALF AND MOVE
OFF TO THE EAST.  ALTHOUGH KINEMATIC PARAMETERS ARE NOT AS
STRONG...HEIGHTENED INSTABILITY MAY OFFSET THAT SOMEWHAT WITH MORE
SVR WX POSSIBLE.  CONVECTIVE CHANCES SHOULD THEN FINALLY DIMINISH
INTO THE NIGHT.

PCPN TOMORROW MAY RESULT A DECENT TEMP GRADIENT SO HAVE COOLED
THINGS OFF NE AND WARMED THEM SW...BELOW AND ABOVE RELATIVELY
GUIDANCE EXTREMES.  NOT AS MUCH OF A CHANGE FRI BUT STILL TRIMMED
HIGHS NE DUE TO PCPN.

.LONG TERM...SAT THROUGH WED
CONVECTIVE TRENDS WILL AGAIN BE THE PREDOMINATE WX CONCERN THIS
PERIOD...BUT OVERALL LESS ACTIVE THAN THE END OF THIS WORK WEEK.
FAIR WX SHOULD BE IN PLACE FOR THE WEEKEND AS WEAK ROCKIES RIDGING
SLOWLY ADVANCES TOWARD THE MO VALLEY AFTER PASSAGE OF LATE WEEK
FRONT.  GENERALLY FOLLOWED BLEND OF GEFS/ECMWF INTO NEXT WEEK WITH
INFLUENCES FROM HPC AND ECMWF MEAN.  RIDGE SHOULD MOVE FAR ENOUGH
EAST TO GET IA INTO THE WARM ADVECTION ZONE BY LATE SUN NIGHT INTO
MONDAY.  THIS SHOULD BE FOLLOWED BY A PROLONGED PERIOD OF IL-DEFINED
CHANCES WITH MODEL CONCENSUS SMOOTHING OUT ANY DETAILS.  THIS
SCENARIO WOULD SEEM TO KEEP CONVECTIVE POTENTIAL ELEVATED WITH
RELATIVELY WEAK LOW LEVEL FLOW IN PLACE AND SFC BOUNDARYS REMAINING
TO OUR SOUTH AND WEST.  ECMWF DOES DEPICT A VERY STRONG SYSTEM
AROUND WED...BUT THIS WILL BE IGNORED FOR THE TIME BEING CONSIDERING
IT IS DAY 7 WITH LITTLE ADDITIONAL SUPPORT AT THE MOMENT.  NO
SIGNIFICANT CHANGES TO GOING TEMPS WITH RELATIVELY FLAT SEASONAL
READINGS ANTICIPATED.

&&

.HYDROLOGY...
MANY HEAVY RAIN AND FLOODING PARAMETERS ARE IN PLACE FOR THU NIGHT.
310K/H85 MOISTURE TRANSPORT AND CONVERGENCE IS VERY STRONG INTO
CENTRAL IA WITH PWS APPROACHING 2 INCHES...VERY ANOMALOUS FOR LATE
MAY...AND EVEN EXCEEDING THAT IN ISOLATED SPOTS.  12-13KFT WCDS WILL
MAKE FOR VERY EFFICIENT RAINERS.  ONLY DRAWBACK WILL BE FAST MEAN
WIND AND SYSTEM MOTION.  ALTHOUGH PATTERN DOES FIT CONCEPTUAL UPPER
AND LOW LEVEL JET MODELS SOMEWHAT...ULJ MAY BE TOO CLOSE AND PUSH
THE MCS OUT QUICK ENOUGH.  STRENGTH OF MEAN WIND AND LLJ ALSO
RESULTS IN RELATIVELY TRANSIENT CORFIDI VECTORS.  BECAUSE THIS IS
3RD PERIOD AND ABOVE CONCERNS...WILL NOT GO WITH FLASH FLOOD WATCH
YET BUT CONTINUE ESF.  FFA COULD CERTAINLY BE NEEDED BY MID SHIFT OR
TOMORROW HOWEVER WITH STORM TOTAL PCPN 1-3.5 INCHES IN GRIDS AT THE
MOMENT.

&&

.AVIATION...29/06Z
THUNDERSTORMS HAVE FIRED OVER NORTHEAST AND CENTRAL NEBRASKA.
PRIMARY CONCERN FOR TAF SITES WILL BE THE CENTRAL NEBRASKA
CONVECTION WITH STORM MOTION VECTORS BRINGING THIS INTO NORTHERN TAF
SITES LATE THROUGH EARLY FRIDAY MORNING. ADDITIONAL CONVECTION
EXPECTED NEAR DSM/FOD/MCW LATE THURSDAY AFTERNOON WITH POTENTIAL
CONTINUING THURSDAY EVENING. VFR CONDTIONS EXPECTED TO MAINTAIN AT
OTM THROUGH THE PERIOD AND AT DSM FOR MUCH OF THE PERIOD.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

LONG TERM/SHORT TERM...SMALL/RUSSELL
AVIATION...DONAVON

Hazardous weather outlook, May 29, 9:10 AM CST, 1 hour 50 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1010 AM CDT THU MAY 29 2008

IAZ004>007-015>017-023>028-033>039-044>050-057>062-301100-
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-
1010 AM CDT THU MAY 29 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

WIDESPREAD THUNDERSTORMS THIS MORNING SHOULD MAINLY BE BELOW SEVERE
LIMITS. AN ISOLATED STORM MAY PRODUCE SEVERE HAIL OR GUSTY
WINDS...BUT SIGNIFICANT SEVERE WEATHER IS UNLIKELY.

WIDESPREAD THUNDERSTORMS ARE FORECAST AGAIN TONIGHT HOWEVER. THE
STORMS MAY BE SEVERE AND CAPABLE OF PRODUCING HEAVY RAIN. SEVERE
WEATHER IS MOST LIKELY WEST OF I35 WITH THE HIGHEST RISK WEST OF
FORT DODGE. ALL SEVERE WEATHER THREATS ARE POSSIBLE INCLUDING
DAMAGING WINDS...LARGE HAIL AND TORNADOES. TO THE EAST OF I35...THE
PRIMARY SEVERE WEATHER RISKS WILL BE DAMAGING WINDS AND LARGE HAIL.

WIDESPREAD RAINFALL OF ONE TO TWO INCHES IS POSSIBLE ALONG WITH
LOCALLY HIGHER AMOUNTS. A FLASH FLOOD WATCH IS IN EFFECT FOR
TONIGHT. PLEASE CHECK THE LATEST BULLETIN ON THE NATIONAL WEATHER
SERVICE DES MOINES WEBSITE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THUNDERSTORM CHANCES LINGER INTO FRIDAY AND FRIDAY EVENING. THERE
IS A SLIGHT CHANCE OF SEVERE WEATHER FRIDAY EAST OF I35 WITH LARGE
HAIL AND DAMAGING WINDS THE PRIMARY THREAT.

MORE THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK BUT IT IS TOO
EARLY TO DETERMINE IF THEY WILL BE CAPABLE OF PRODUCING SEVERE
WEATHER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY TONIGHT. SPOTTER ACTIVATION MAY BE
NEEDED FROM TIME TO TIME AFTER TONIGHT FOR THE NEXT WEEK.

AN EMERGENCY MANAGER CONFERENCE CALL HAS BEEN SCHEDULED FOR 200 PM
THIS THURSDAY AFTERNOON.

IAZ070>075-081>086-092>097-301100-
CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS-
MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
1010 AM CDT THU MAY 29 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS THIS MORNING SHOULD BE BELOW
SEVERE LIMITS.

WIDESPREAD THUNDERSTORMS ARE FORECAST TONIGHT. THE STORMS MAY BE
SEVERE AND CAPABLE OF PRODUCING HEAVY RAIN. SEVERE WEATHER IS
MOST LIKELY WEST OF I35 WITH THE HIGHEST RISK WEST OF CRESTON.
ALL SEVERE WEATHER THREATS ARE POSSIBLE INCLUDING DAMAGING
WINDS...LARGE HAIL AND ISOLATED TORNADOES. TO THE EAST OF
I35...THE PRIMARY SEVERE WEATHER RISKS WILL BE DAMAGING WINDS AND
LARGE HAIL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THUNDERSTORM CHANCES ARE IN THE FORECAST THURSDAY THROUGH FRIDAY
NIGHT. THE BEST CHANCE FOR SEVERE WEATHER WILL BE LATE THURSDAY
AFTERNOON AND EVENING. ALL SEVERE WEATHER THREATS WILL BE POSSIBLE
INCLUDING LARGE HAIL...DAMAGING WINDS AND ISOLATED TORNADOES. THE
BEST CHANCE FOR HEAVY RAIN IS THURSDAY NIGHT AND IT MAY RESULT IN
FLOODING.

THUNDERSTORM CHANCES LINGER INTO FRIDAY AND FRIDAY EVENING. THERE
IS A SLIGHT CHANCE OF SEVERE WEATHER FRIDAY EAST OF I35 WITH LARGE
HAIL AND DAMAGING WINDS THE PRIMARY THREAT.

MORE THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK BUT IT IS TOO
EARLY TO DETERMINE IF THEY WILL BE CAPABLE OF PRODUCING SEVERE
WEATHER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY TONIGHT. SPOTTER ACTIVATION MAY BE
NEEDED FROM TIME TO TIME AFTER TONIGHT FOR THE NEXT WEEK.

AN EMERGENCY MANAGER CONFERENCE CALL HAS BEEN SCHEDULED FOR 200 PM
THIS THURSDAY AFTERNOON.

JOHNSON/SMALL

In the hours before

Local storm report, May 29, 8:37 AM CST, 2 hours 23 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
937 AM CDT THU MAY 29 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0927 AM     TSTM WND GST     BADGER                  42.61N 94.14W
05/29/2008  E70 MPH          WEBSTER            IA   TRAINED SPOTTER

            VERY STRONG WINDS LASTED AROUND 3 MINUTES ALONG WITH PEA
            SIZED HAIL AND EXTREMELY HEAVY RAIN.

&&

SSEARCY

Local storm report, May 29, 9:07 AM CST, 1 hour 53 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1007 AM CDT THU MAY 29 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0925 AM     TSTM WND DMG     BADGER                  42.61N 94.14W
05/29/2008                   WEBSTER            IA   TRAINED SPOTTER

            METAL ROOF BENT FROM HIGH WIND SPEEDS.

&&

DEROY

The radar

The Des Moines radar (KDMX), 63 km away, was scanning. The volume nearest the first event began at 16:59 UTC.

Open the radar archive at this moment

Event by event

33 thunderstorm wind, 12 tornado, 8 flash flood, 7 heavy rain, 4 hail, 4 flood, 1 lightning, 1 funnel cloud. Local standard time, as filed.

Heavy Rain, Greene

When: May 29, 11:00 AM CST to 1:30 PM CST
Where: Greene County, Jefferson
Reported by: Trained Spotter
Coordinates: 42.020, -94.380

Rainfall of 2.90 inches fell between 1100 and 1330 CDT.

Heavy Rain, Greene

When: May 29, 4:30 PM CST
Where: Greene County, 2.07 mi N of Jefferson
Reported by: Trained Spotter
Coordinates: 42.050, -94.380

A farm location north of Highway 30 at Highway 4 reported in excess of 4 inches of rain during the afternoon.

Hail, Sac

When: May 29, 7:17 PM CST
Where: Sac County, 3.6 mi SSE of Odebolt
Measured: 0.88 in hail
Property damage: $1,000
Reported by: Trained Spotter
Coordinates: 42.270, -95.250

Thunderstorm Wind, Sac

When: May 29, 7:27 PM CST
Where: Sac County, 1.72 mi SE of Odebolt
Measured: 50 kt (58 mph) estimated gust
Property damage: $1,000
Reported by: Law Enforcement
Coordinates: 42.300, -95.250

Trees fell across Highway 39.

Thunderstorm Wind, Sac

When: May 29, 7:27 PM CST
Where: Sac County, 1.23 mi SE of Odebolt
Measured: 52 kt (60 mph) estimated gust
Property damage: $10,000
Reported by: Law Enforcement
Coordinates: 42.310, -95.250

A tree fell on a house and vehicle.

Thunderstorm Wind, Sac

When: May 29, 7:27 PM CST
Where: Sac County, Sac City
Measured: 52 kt (60 mph) estimated gust
Property damage: $2,000
Reported by: Law Enforcement
Coordinates: 42.420, -95.000

Several large tree limbs were downed.

Tornado, Crawford

When: May 29, 7:37 PM CST to 7:38 PM CST
Where: Crawford County, 1.06 mi WSW of Dow City to 0.42 mi SSW of Dow City
Rating: EF0
Path length: 0.84 mi
Path width: 50 yd
Property damage: $30,000
Reported by: Emergency Manager
Coordinates: 41.923, -95.519

Damage was done to a farm house with shingles removed and tree damage to the yard. Windows were also blown out of the house.

Thunderstorm Wind, Crawford

When: May 29, 7:45 PM CST
Where: Crawford County, 4.16 mi E of Denison
Measured: 61 kt (70 mph) estimated gust
Property damage: $5,000
Reported by: Trained Spotter
Coordinates: 42.010, -95.270

Two trees were blown down.

Thunderstorm Wind, Crawford

When: May 29, 7:45 PM CST
Where: Crawford County, Denison
Measured: 61 kt (70 mph) estimated gust
Property damage: $5,000
Reported by: Trained Spotter
Coordinates: 42.020, -95.350

Two large trees were blown down.

Tornado, Crawford

When: May 29, 7:46 PM CST to 7:49 PM CST
Where: Crawford County, 2.56 mi E of Denison to 3.6 mi SW of Vail
Rating: EF1
Path length: 2.5 mi
Path width: 75 yd
Property damage: $150,000
Crop damage: $10,000
Reported by: Trained Spotter
Coordinates: 42.023, -95.300

Tornado took a barn roof off, some of the shingles of the house were blown off and numerous trees were downed. A hog confinement was leveled and damage was done to a trailer park.

Thunderstorm Wind, Carroll

When: May 29, 8:02 PM CST
Where: Carroll County, 2.17 mi ENE of Manning
Measured: 57 kt (66 mph) estimated gust
Property damage: $3,000
Reported by: Emergency Manager
Coordinates: 41.910, -95.030

Two vehicles were blown off of the road.

Tornado, Carroll

When: May 29, 8:10 PM CST to 8:16 PM CST
Where: Carroll County, 2.17 mi ESE of Templeton to 1.2 mi NNW of Dedham
Rating: EF1
Path length: 4.1 mi
Path width: 100 yd
Property damage: $200,000
Crop damage: $10,000
Reported by: Trained Spotter
Coordinates: 41.910, -94.910

A tornado damaged 3 farmsteads in southern Carroll County as it moved east from near Templeton toward Dedham. A machine shed was completely destroyed and numerous outbuildings sustained damage. Widespread tree damage was also reported.

Lightning, Carroll

When: May 29, 8:15 PM CST
Where: Carroll County, Carroll
Injuries: 1 direct, 0 indirect
Reported by: Newspaper
Coordinates: 42.070, -94.880

Tornado, Calhoun

When: May 29, 8:23 PM CST to 8:27 PM CST
Where: Calhoun County, 1.72 mi NW of Somers to 2.06 mi NE of Somers
Rating: EF1
Path length: 2.76 mi
Path width: 100 yd
Property damage: $50,000
Reported by: Law Enforcement
Coordinates: 42.398, -94.454

A small tornado moved across the northern part of town, causing roof damage to homes and garages.

Tornado, Calhoun

When: May 29, 8:25 PM CST to 8:28 PM CST
Where: Calhoun County, 1.69 mi W of Farnhamville to 0.69 mi ENE of Farnhamville
Rating: EF0
Path length: 2.35 mi
Path width: 50 yd
Property damage: $30,000
Reported by: Law Enforcement
Coordinates: 42.276, -94.433

A tornado caused damage to 4 farmsteads with damage to trees and some minor damage to the farmstead.

Thunderstorm Wind, Webster

When: May 29, 8:27 PM CST
Where: Webster County, 2.05 mi E of Farnhamville
Measured: 61 kt (70 mph) estimated gust
Property damage: $5,000
Reported by: Broadcast Media
Coordinates: 42.282, -94.360

Building debris was reported blown onto Highway D60 just north of Highway 175 near Gowrie. Report from KCCI TV.

Thunderstorm Wind, Webster

When: May 29, 8:27 PM CST
Where: Webster County, 2.04 mi E of Farnhamville
Measured: 61 kt (70 mph) estimated gust
Property damage: $5,000
Reported by: Emergency Manager
Coordinates: 42.280, -94.360

Minor damage reported to a house, machine shed was destroyed and a tree was damaged.

Thunderstorm Wind, Webster

When: May 29, 8:45 PM CST
Where: Webster County, 0.69 mi S of Vincent
Measured: 61 kt (70 mph) estimated gust
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 42.590, -94.020

Several trees were downed along with tree limbs in the Vincent area.

Thunderstorm Wind, Hamilton

When: May 29, 8:50 PM CST
Where: Hamilton County, 2.95 mi SSE of Webster City Arpt
Measured: 57 kt (66 mph) estimated gust
Property damage: $3,000
Reported by: Law Enforcement
Coordinates: 42.390, -93.850

Trees were damaged.

Thunderstorm Wind, Hamilton

When: May 29, 8:50 PM CST
Where: Hamilton County, 2.81 mi S of Webster City Arpt
Measured: 61 kt (70 mph) estimated gust
Property damage: $10,000
Reported by: Law Enforcement
Coordinates: 42.390, -93.860

A garage was destroyed and debris was strewn in the field.

Hail, Guthrie

When: May 29, 9:42 PM CST
Where: Guthrie County, 3.9 mi N of Dale
Measured: 0.88 in hail
Crop damage: $5,000
Reported by: Emergency Manager
Coordinates: 41.656, -94.357

Also accompanied by 50 MPH winds.

Thunderstorm Wind, Butler

When: May 29, 9:45 PM CST
Where: Butler County, 2.06 mi SW of Aplington
Measured: 61 kt (70 mph) estimated gust
Property damage: $40,000
Reported by: Law Enforcement
Coordinates: 42.560, -92.910

Law enforcement reported a machine shed and barn blown down.

Hail, Guthrie

When: May 29, 9:48 PM CST
Where: Guthrie County, 5.67 mi E of Fanslers
Measured: 1 in hail
Property damage: $2,000
Crop damage: $5,000
Reported by: Emergency Manager
Coordinates: 41.750, -94.360

Thunderstorm Wind, Butler

When: May 29, 9:50 PM CST
Where: Butler County, Aplington
Measured: 57 kt (66 mph) estimated gust
Property damage: $5,000
Reported by: Law Enforcement
Coordinates: 42.580, -92.880

Trees were reportedly blown down and a stop sign was bent.

Hail, Guthrie

When: May 29, 9:56 PM CST
Where: Guthrie County, 4.94 mi SSE of Jamaica
Measured: 0.88 in hail
Crop damage: $5,000
Reported by: Emergency Manager
Coordinates: 41.780, -94.300

Hail was also accompanied by strong winds.

Tornado, Dallas

When: May 29, 10:06 PM CST
Where: Dallas County, 1.72 mi SW of Gardiner
Rating: EF0
Path length: 0.1 mi
Path width: 25 yd
Reported by: Trained Spotter
Coordinates: 41.760, -94.070

A brief tornado touchdown occurred with little or no damage.

Flash Flood, Crawford

When: May 29, 10:32 PM CST to May 30, 3:30 AM CST
Where: Crawford County, 6.21 mi SW of Dow City to 1.22 mi W of Dow City
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 41.870, -95.590

Highway 30 north of Dunlap was flooded.

Funnel Cloud, Jasper

When: May 29, 11:30 PM CST
Where: Jasper County, 1.38 mi N of Baxter
Reported by: Law Enforcement
Coordinates: 41.840, -93.150

A funnel cloud was reported 1 mile north of Baxter.

Tornado, Dallas

When: May 29, 11:50 PM CST to 11:55 PM CST
Where: Dallas County, 0.86 mi NW of Kennedy to 2.49 mi NW of Adel
Rating: EF1
Path length: 3.68 mi
Path width: 150 yd
Property damage: $100,000
Crop damage: $5,000
Reported by: NWS Storm Survey
Coordinates: 41.630, -94.130

Power lines and trees were damaged as well as farm outbuildings being damaged or destroyed.

Flash Flood, Carroll

When: May 29, 11:53 PM CST to May 30, 4:45 AM CST
Where: Carroll County, 2.47 mi SE of Mt Carmel to 1.72 mi E of Mt Carmel
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 42.130, -94.860

Water was over Highway 71 north of Carroll.

Flash Flood, Greene

When: May 29, 11:55 PM CST to May 30, 4:45 AM CST
Where: Greene County, 3.34 mi NNW of Farlin to 3.16 mi ENE of Farlin
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 42.121, -94.485

Two feet of water was reported over Highway 4 north of Farlin.

Flash Flood, Story

When: May 30, 12:11 AM CST to 5:30 AM CST
Where: Story County, 2.28 mi S of Shipley to 1.89 mi NE of Cambridge
Cause: Heavy Rain
Property damage: $50,000
Crop damage: $10,000
Reported by: Trained Spotter
Coordinates: 41.947, -93.516

Water was reported over gravel roads from drainage from farm fields.

Flash Flood, Story

When: May 30, 12:25 AM CST to 5:30 AM CST
Where: Story County, 2.49 mi NE of Ames to 3.1 mi NNW of Ames
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 42.056, -93.586

Water was reported over the road at the intersection of 180th and U.S. Highway 69.

Thunderstorm Wind, Union

When: May 30, 12:38 AM CST
Where: Union County, 0.87 mi SE of Creston
Measured: 50 kt (58 mph) measured gust
Property damage: $3,000
Reported by: Mesonet
Coordinates: 41.060, -94.360

Report from a schoolnet site.

Thunderstorm Wind, Union

When: May 30, 12:41 AM CST
Where: Union County, 0.87 mi SE of Creston
Measured: 50 kt (58 mph) measured gust
Property damage: $3,000
Reported by: Mesonet
Coordinates: 41.060, -94.360

Reported wind gust from a schoolnet site.

Thunderstorm Wind, Union

When: May 30, 12:43 AM CST
Where: Union County, 0.52 mi E of Creston Arpt
Measured: 50 kt (58 mph) measured gust
Reported by: AWOS
Coordinates: 41.020, -94.360

Thunderstorm Wind, Union

When: May 30, 12:47 AM CST
Where: Union County, 0.87 mi SE of Creston
Measured: 56 kt (64 mph) measured gust
Reported by: Mesonet
Coordinates: 41.060, -94.360

Report received from the Creston RWIS site.

Flash Flood, Greene

When: May 30, 1:23 AM CST to 4:45 AM CST
Where: Greene County, 3.02 mi SSW of Scranton to 1.43 mi SSW of Jefferson Muni Arpt
Cause: Heavy Rain
Property damage: $100,000
Crop damage: $10,000
Reported by: Law Enforcement
Coordinates: 41.988, -94.564

Numerous locations have water across the road throughout the county. Locations include Highway 25 south of Scranton, Old Highway 30 east and west of Jefferson, Highway 4 north of Jefferson. A car went into the ditch after losing control driving through the water.

Thunderstorm Wind, Union

When: May 30, 3:00 AM CST
Where: Union County, 0.87 mi SE of Creston
Measured: 52 kt (60 mph) estimated gust
Property damage: $3,000
Reported by: Trained Spotter
Coordinates: 41.060, -94.360

Thunderstorm Wind, Union

When: May 30, 3:12 AM CST
Where: Union County, 2.14 mi SSE of Lorimor
Measured: 50 kt (58 mph) estimated gust
Property damage: $2,000
Reported by: Law Enforcement
Coordinates: 41.100, -94.060

Tree limbs were blown down on the road.

Tornado, Clarke

When: May 30, 3:13 AM CST to 3:24 AM CST
Where: Clarke County, 2.24 mi WNW of Murray to 4.03 mi WNW of Osceola Muni Arpt
Rating: EF1
Path length: 9.07 mi
Path width: 150 yd
Property damage: $50,000
Reported by: NWS Storm Survey
Coordinates: 41.061, -94.010

Damage was primarily done to outbuildings, power lines, and trees.

Thunderstorm Wind, Clarke

When: May 30, 3:16 AM CST
Where: Clarke County, 1.25 mi ESE of Murray
Measured: 59 kt (68 mph) measured gust
Property damage: $10,000
Reported by: Mesonet
Coordinates: 41.040, -93.950

Reported by a schoolnet site.

Thunderstorm Wind, Clarke

When: May 30, 3:21 AM CST
Where: Clarke County, 1.25 mi ESE of Murray
Measured: 64 kt (74 mph) measured gust
Property damage: $10,000
Reported by: Mesonet
Coordinates: 41.040, -93.950

Reported by a schoolnet site.

Thunderstorm Wind, Union

When: May 30, 3:30 AM CST
Where: Union County, 0.52 mi E of Lorimor
Measured: 52 kt (60 mph) estimated gust
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 41.130, -94.060

Large limbs and branches were downed in the Lorimor and Creston areas.

Thunderstorm Wind, Lucas

When: May 30, 3:45 AM CST
Where: Lucas County, 1.25 mi WNW of Lucas
Measured: 61 kt (70 mph) estimated gust
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 41.040, -93.490

Windows were blown out of a house.

Thunderstorm Wind, Warren

When: May 30, 3:45 AM CST
Where: Warren County, 2.74 mi SW of Milo
Measured: 61 kt (70 mph) estimated gust
Property damage: $35,000
Reported by: Fire Department/Rescue
Coordinates: 41.248, -93.481

A barn and trees were blown down in the 5700 block of 170th St.

Thunderstorm Wind, Warren

When: May 30, 3:50 AM CST
Where: Warren County, 2.81 mi S of Lacona
Measured: 61 kt (70 mph) estimated gust
Property damage: $25,000
Reported by: Emergency Manager
Coordinates: 41.160, -93.370

A grain bin was destroyed and power lines were downed.

Thunderstorm Wind, Warren

When: May 30, 3:50 AM CST
Where: Warren County, 2.19 mi WSW of Lacona
Measured: 65 kt (75 mph) estimated gust
Property damage: $50,000
Reported by: Emergency Manager
Coordinates: 41.190, -93.420

Major building damage was reported with cars rolled over.

Thunderstorm Wind, Lucas

When: May 30, 3:51 AM CST
Where: Lucas County, 3.45 mi N of Oakley
Measured: 61 kt (70 mph) estimated gust
Property damage: $15,000
Reported by: Emergency Manager
Coordinates: 41.150, -93.380

Large trees were blown down with damage across northern Lucas County.

Tornado, Warren

When: May 30, 3:51 AM CST to 3:54 AM CST
Where: Warren County, 2.59 mi S of Lacona to 3.65 mi SE of Lacona
Rating: EF1
Path length: 2.7 mi
Path width: 125 yd
Continued into: Marion, Ia (DMX)
Property damage: $30,000
Crop damage: $5,000
Reported by: NWS Storm Survey
Coordinates: 41.163, -93.380

A tornado caused damage to trees, farm buildings, and power lines. The tornado moved out of Warren County and into Marion County.

Tornado, Marion

When: May 30, 3:54 AM CST to 4:00 AM CST
Where: Marion County, 1.2 mi SSW of Newbern to 3.49 mi S of Melcher
Rating: EF1
Path length: 4.5 mi
Path width: 125 yd
Property damage: $50,000
Crop damage: $5,000
Reported by: NWS Storm Survey
Coordinates: 41.164, -93.329

A tornado caused damage to trees, farm buildings, and power lines. The tornado moved into the county from Warren County.

Thunderstorm Wind, Warren

When: May 30, 3:56 AM CST
Where: Warren County, 0.69 mi S of Lacona
Measured: 56 kt (64 mph) estimated gust
Property damage: $10,000
Reported by: Fire Department/Rescue
Coordinates: 41.190, -93.380

Winds were estimated at 60 to 70 MPH.

Thunderstorm Wind, Lucas

When: May 30, 4:00 AM CST
Where: Lucas County, 3.75 mi ESE of Newbern
Measured: 61 kt (70 mph) estimated gust
Property damage: $5,000
Reported by: Emergency Manager
Coordinates: 41.150, -93.260

House and power pole damage were reported.

Thunderstorm Wind, Lucas

When: May 30, 4:00 AM CST
Where: Lucas County, 2.14 mi SSE of Newbern
Measured: 65 kt (75 mph) estimated gust
Property damage: $25,000
Reported by: Emergency Manager
Coordinates: 41.150, -93.310

A roof was blown off of a house.

Tornado, Marion

When: May 30, 4:07 AM CST to 4:21 AM CST
Where: Marion County, 3.79 mi NNE of Columbia to 1.48 mi SSE of Tracy
Rating: EF2
Path length: 12.28 mi
Path width: 900 yd
Continued into: Mahaska, Ia (DMX)
Injuries: 10 direct, 0 indirect
Property damage: $750,000
Crop damage: $25,000
Reported by: NWS Storm Survey
Coordinates: 41.230, -93.120

Several homes were damaged or destroyed, two mobile homes were destroyed. Considerable tree damage was reported. The EF2 damage occurred in the Attica area, along with 10 injuries. The tornado moved out of Marion County into Mahaska County.

Flash Flood, Story

When: May 30, 4:11 AM CST to 5:30 AM CST
Where: Story County, 0.71 mi SSW of Ontario to 1.17 mi W of Story City
Cause: Heavy Rain
Property damage: $250,000
Crop damage: $25,000
Reported by: Emergency Manager
Coordinates: 42.021, -93.686

Numerous roads were under water around the county, especially across the north. Lincoln Highway and E-18 were under water in places.

Thunderstorm Wind, Marion

When: May 30, 4:13 AM CST
Where: Marion County, 1.25 mi ENE of Bussey
Measured: 65 kt (75 mph) estimated gust
Property damage: $50,000
Reported by: Broadcast Media
Coordinates: 41.210, -92.880

A garage was damaged and the roof taken off of a house. Reported by KCCI TV.

Flash Flood, Sac

When: May 30, 4:16 AM CST to 7:00 AM CST
Where: Sac County, 2.08 mi WNW of Ulmer to 1.21 mi E of Carnarvon
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 42.276, -94.990

Water was reported over the road at 175th and Voss Ave.

Tornado, Mahaska

When: May 30, 4:21 AM CST to 4:28 AM CST
Where: Mahaska County, 4.94 mi SSW of Olivet to 0.65 mi W of Beacon
Rating: EF1
Path length: 6.9 mi
Path width: 250 yd
Property damage: $75,000
Crop damage: $10,000
Reported by: NWS Storm Survey
Coordinates: 41.256, -92.872

Thunderstorm Wind, Mahaska

When: May 30, 4:30 AM CST
Where: Mahaska County, 0.86 mi SE of Oskaloosa
Measured: 50 kt (58 mph) estimated gust
Reported by: Broadcast Media
Coordinates: 41.290, -92.640

Thunderstorm Wind, Mahaska

When: May 30, 4:39 AM CST
Where: Mahaska County, 0.86 mi SE of Oskaloosa
Measured: 56 kt (64 mph) estimated gust
Property damage: $5,000
Reported by: Trained Spotter
Coordinates: 41.290, -92.640

Flood, Black Hawk

When: May 30, 6:11 AM CST to 12:00 PM CST
Where: Black Hawk County, 0.86 mi SE of La Porte City to 0.41 mi S of La Porte City
Cause: Heavy Rain
Property damage: $25,000
Reported by: Law Enforcement
Coordinates: 42.310, -92.190

Water was over Highway 218 near La Porte City.

Flood, Tama

When: May 30, 6:11 AM CST to 12:00 PM CST
Where: Tama County, 4.32 mi NW of Toledo to 4.54 mi W of Tama Arpt
Cause: Heavy Rain
Property damage: $100,000
Crop damage: $10,000
Reported by: Broadcast Media
Coordinates: 42.037, -92.648

Numerous roads were under water around the county.

Flood, Story

When: May 30, 6:15 AM CST to 11:49 PM CST
Where: Story County, 2.4 mi NW of Kelley to 3.02 mi NNW of Gilbert
Cause: Heavy Rain
Property damage: $250,000
Crop damage: $50,000
Reported by: Emergency Manager
Coordinates: 41.978, -93.708

Numerous roads were under water, including E-18 and Lincoln Highway.

Heavy Rain, Carroll

When: May 30, 6:20 AM CST
Where: Carroll County, 1.47 mi SSE of Manning
Reported by: Trained Spotter
Coordinates: 41.880, -95.060

Heavy Rain, Hardin

When: May 30, 6:20 AM CST
Where: Hardin County, Buckeye
Reported by: COOP Observer
Coordinates: 42.420, -93.380

Heavy Rain, Kossuth

When: May 30, 6:20 AM CST
Where: Kossuth County, 0.5 mi W of Swea City
Reported by: Trained Spotter
Coordinates: 43.380, -94.310

Heavy Rain, Sac

When: May 30, 6:20 AM CST
Where: Sac County, Sac City
Reported by: COOP Observer
Coordinates: 42.420, -95.000

Heavy Rain, Tama

When: May 30, 6:38 AM CST
Where: Tama County, Clutier
Reported by: COOP Observer
Coordinates: 42.080, -92.400

Flood, Story

When: May 30, 4:50 PM CST to 11:49 PM CST
Where: Story County, 1.37 mi SW of Nevada Muni Arpt to 2.77 mi NW of Nevada Muni Arpt
Cause: Heavy Rain
Property damage: $50,000
Reported by: Emergency Manager
Coordinates: 42.004, -93.496

Highway 30 was closed at the intersection of Interstate 35. Traffic going into Ames and Nevada was being rerouted.

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.
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.
Tornado: A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.
Lightning: A lightning strike that killed, injured or caused damage.
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.
Funnel Cloud: A rotating column of cloud extending from a thunderstorm that did not reach the ground.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

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

The same day elsewhere

Every storm in Iowa in 2008 Every state in 2008 This day in weather history The tornado archive for Iowa, 2008 Warnings in Iowa, May 2008

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: 91591, 91592, 91587, 91600, 91601, 91602, 91646, 91604, 91605, 91648, 91607, 91649, 98465, 91650, 91651, 91609, 91610, 91611, 91612, 91613, 91589, 91614, 91588, 91615, 91590, 91653, 91573, 91586, 91654, 91574, 91575, 91576, 91577, 91636, 91637, 91638, 91639, 91578, 91640, 91623, and more.