Tornadoes · United States · Iowa · 2004

F1 tornado, Warren County, Iowa, May 22, 2004

This F1 tornado ran 7.0 miles across Warren County on May 22, 2004, touching down at 12:02 AM CDT and reaching 250 yards wide. It killed nobody, and did $100,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mphthis tornado

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 mph

    Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

  4. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 mph

    Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

  7. Unrated

    The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating
F1
Date
May 22, 2004
Touchdown
12:02 AM CDT (05:02 UTC)
Path length
7.0 miles (11.3 km)
Path width
250 yards (229 m)
Deaths
0
Injuries
0
Property damage
$100,000
County
Warren County
Touchdown point
41.350, -93.800
Lift-off point
41.380, -93.670
Record number
923

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

Issued (UTC)ExpiredProductOffice
00:23 UTC01:00 UTCTornado WarningDMX
04:09 UTC05:00 UTCSevere Thunderstorm WarningDMX

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Moderate Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:01 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Omaha, NE (KOAX), 00:00Z

5.0 hours before the tornado, 220 km from the path. May 23, 2004.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2004-05-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2882 joules per kilogram, CIN -5, lifted condensation level 1091 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Omaha, NE at 00:00Z on 2004-05-23The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 51 square meters per square second, 0 to 6 km bulk shear 64 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
2882 J/kg
Mixed-layer CIN
-5 J/kg
Surface CAPE
3473 J/kg
Mixed-layer LCL
1091 m above ground
0-6 km bulk shear
64 kt
0-1 km bulk shear
6 kt
0-1 km storm-relative helicity
51 m²/s²
0-3 km storm-relative helicity
260 m²/s²
Significant tornado parameter
4.2
Supercell composite
16.7
0-3 km lapse rate
6.7 K/km

Open this sounding in Storm Lab

Omaha, NE (KOAX), 12:00Z

7.0 hours after it, 220 km from the path. May 23, 2004.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2004-05-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 164 joules per kilogram, CIN -322, lifted condensation level 534 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Omaha, NE at 12:00Z on 2004-05-23The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -4 square meters per square second, 0 to 6 km bulk shear 68 knots.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
164 J/kg
Mixed-layer CIN
-322 J/kg
Surface CAPE
49 J/kg
Mixed-layer LCL
534 m above ground
0-6 km bulk shear
68 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
45 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.0 K/km

Open this sounding in Storm Lab

The surface observations

Des Moines (DSM), 20 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
03:04 UTC71.666.270° 6 kt1000.7
03:54 UTC696150° 16 kt1000.7
04:07 UTC66.260.8330° 13 kt1001-TSRA
04:14 UTC64.460.840° 21 kt1001-TSRA
04:45 UTC64.462.670° 15 kt21999.7-TSRA
04:54 UTC636280° 11 kt211000-TSRA
05:00 UTC64.462.6190° 16 kt371002.7-TSRA BR SQ
05:05 UTC66.260.8200° 13 kt371002-TSRA SQ
05:17 UTC64.460.8220° 3 kt1001.4-TSRA BR
05:44 UTC62.662.6150° 12 kt1002-TSRA
05:54 UTC6161160° 7 kt1000.3-TSRA
06:13 UTC62.662.6240° 10 kt1001.4-TSRA BR
06:22 UTC62.662.6250° 14 kt1002.4-TSRA
06:54 UTC6362300° 5 kt1002-TSRA BR

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Des Moines radar (KDMX), 41 km away, was scanning. The volume nearest the touchdown began at 05:01 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
02:06 UTCTORNADO2 W AllemanPolk, IATORNADO 2 MI WEST OF ALLEMAN
02:13 UTCTORNADOJohnstonPolk, IA
02:23 UTCTORNADOAllemanPolk, IATORNADO DOWN WITH DEBRIS
02:36 UTCFLASH FLOODMadridBoone, IAWATER 1 FOOT DEEP ON HIGHWAY 17 SOUTH OF MADRID, ALSO PARTS OF HIGHWAY 17 IN DALLAS, POLK, AND BOONE COUNTIES.
02:47 UTCFLASH FLOOD7 S PerryDallas, IAMAJOR ROADS FLOODED OVER MUCH OF NORTHERN DALLAS COUNTY. CAR IN DITCH, DIVE TEAM HAS BEEN DISPATCHED TO RESCUE.
02:53 UTCFLASH FLOODHuxleyStory, IAWATER UP TO THE DORRS OF A CLINIC, PARKS AND ROADS FLOODED.
02:54 UTCFLASH FLOODPolk CityPolk, IA3 FOOT OF WATER OVER THE ROAD IN POLK CITY.
02:58 UTCFLASH FLOOD5 W WoodwardBoone, IAVAN TRIED TO GO THROUGH WATER OVER STATE HIGHWAY 141 AND GOT SWEPT OFF THE ROAD INTO THE DITCH. DRIVER WAS RESCUED
03:15 UTCHAIL 0.88AllemanPolk, IANICKEL SIZED HAIL IN ALLEMAN
03:15 UTCHAIL 0.88AllemanPolk, IA
03:30 UTCHEAVY RAIN 49 E PerryDallas, IA4 INCHES OF RAIN MEASURED 9 MI EAST OF PERRY. WATER OVER HIGHWAYS 210 AND 141. RAINFALL AMOUNTS 3 TO 4 INCHES OVER MUCH OF THE AREA AND STILL RAINING.
04:05 UTCTSTM WND GST 65GreenfieldAdair, IAREPORTED BY EMERGENCY MANAGEMENT.
04:12 UTCFLASH FLOODW AnkenyPolk, IAROCK CREEK IS OUT OF BANKS.
04:12 UTCTSTM WND GST 60GreenfieldAdair, IA
04:27 UTCTSTM WND GST 617 Ne GreenfieldAdair, IA
04:30 UTCTSTM WND DMG5 S WintersetMadison, IADEPUTY VEHICLE BLOWN IN DITCH OFF HIGHWAY 169 AND 265TH STREET. POSSIBLE TORNADO WITH 100 MPH WINDS. GARAGE DESTROYED JUST TO THE EAST. MULTIPLE TREES AND POWER LINES DOWN IN AN EAST-NORTHEAST PATTERN ACROSS COUNTY. REPO
04:45 UTCTSTM WND GST 1063 W St. CharlesMadison, IAMEASURED WINDSPEED.
04:47 UTCTSTM WND GST 60AdelDallas, IAREPORTED BY EMERGENY MANGEMENT.
04:50 UTCTSTM WND GST 652 N CummingPolk, IA
05:01 UTCTORNADO1 Ene Spring HillWarren, IA
05:02 UTCTSTM WND DMGBevingtonWarren, IALARGE TREES DOWN IN BEVINGTON AND MARTINSDALE
05:25 UTCTSTM WND DMGMonroeJasper, IA3 FOOT DIAMETER TREE DOWN ON GARAGE
05:50 UTCTSTM WND DMG4 W PellaMarion, IATRUCK BLOWN OFF OF HIGHWAY 163
05:54 UTCFLASH FLOODPerryDallas, IA5 INCHES OF RAIN MEASURED AND ROADS ARE COVERED WITH WATER.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2004 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of May 22, 2004

64 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 223:58 PM EDTF0Saginaw, MI2.550
May 224:02 PM EDTF0Saginaw, MI0.230
May 222:10 PM MDTF0Goshen, WY0.225
May 224:35 PM EDTF0Shiawassee, MI0.120
May 224:45 PM EDTF1Tuscola, MI1.050$10,000
May 225:10 PM EDTF0Sanilac, MI1.050$20,000
May 223:20 PM MDTF0Logan, CO0.150
May 225:22 PM CDTF0McPherson, NE0.220
May 225:28 PM CDTF0Furnas, NE0.150$10,000
May 225:35 PM CDTF1Furnas, NE3.0400$300,000
May 225:40 PM CDTF0Logan, NE0.110
May 225:40 PM CDTF0Logan, NE2.020
May 225:49 PM CDTF0Harlan, NE0.250$150,000
May 226:04 PM CDTF0Harlan, NE0.2100
May 226:10 PM CDTF0Colfax, NE0.550
May 226:11 PM CDTF0Harlan, NE0.275
May 226:34 PM CDTF1Custer, NE0.220$40,000
May 226:36 PM CDTF0Franklin, NE0.150$10,000
May 226:46 PM CDTF0Webster, NE3.5125$250,000
May 226:50 PM CDTF1Custer, NE0.530$50,000
May 226:53 PM CDTF0Thayer, NE0.275
May 227:00 PM CDTF2Thayer, NE8.0800$2.5 million
May 227:07 PM CDTF1Adair, IA7.1100$50,000
May 227:10 PM CDTF1Adams, NE7.0150$1.0 million
May 227:11 PM CDTF0Madison, IA0.330
May 227:12 PM CDTF0Custer, NE0.210
May 227:13 PM CDTF0Lincoln, NE0.110
May 227:15 PM CDTF1Dodge, NE2.0200
May 227:17 PM CDTF0Custer, NE0.110
May 227:19 PM CDTF2Adams, NE23.0700$5.0 million
May 227:24 PM CDTF0Thayer, NE1.050
May 227:26 PM CDTF1Fillmore, NE2.5100$100,000
May 227:29 PM CDTF1Clay, NE0.225
May 227:30 PM CDTF4Hallam tornado, NE54.04,400138$160 million
May 227:32 PM CDTF1Fillmore, NE2.0150$100,000
May 227:34 PM CDTF0York, NE0.275$40,000
May 227:35 PM CDTF0Jefferson, NE2.080
May 227:45 PM CDTF0Story, IA1.450$2,000
May 227:45 PM CDTF0Dallas, IA0.225
May 227:55 PM CDTF1Dallas, IA5.0100$2,000
May 228:06 PM CDTF0Jasper, IA0.225
May 228:13 PM CDTF0Dallas, IA0.550$1,000
May 228:19 PM CDTF0Harrison, IA0.260
May 228:19 PM CDTF0Marshall, IA0.540
May 228:20 PM CDTF0Jasper, IA0.225
May 228:23 PM CDTF0Jasper, IA0.225
May 228:27 PM CDTF0Dallas, IA0.225
May 228:35 PM CDTF0Jasper, IA0.225
May 228:36 PM CDTF0Jasper, IA1.540$10,000
May 228:40 PM CDTF1Marshall, IA17.0100$10,000
May 228:42 PM CDTF0Republic, KS0.150$10,000
May 228:44 PM CDTF2Republic, KS2.0100$90,000
May 228:45 PM CDTF0Shelby, IA2.0200
May 228:53 PM CDTF1Thayer, NE10.0400$1.0 million
May 228:56 PM CDTF0Republic, KS0.150
May 228:59 PM CDTF0Republic, KS0.150
May 229:06 PM CDTF0Polk, IA2.050
May 229:15 PM CDTF0Tama, IA0.330
May 229:25 PM CDTF0Thayer, NE6.0200$250,000
May 229:30 PM CDTF1Jefferson, NE3.0100

All 65 of them

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.