Tornadoes · United States · Iowa · 2004
F1 tornado, Newhall to Vinton, Iowa, May 21, 2004
From Newhall to Vinton, this F1 tornado ran 1.7 miles across Benton County on May 21, 2004, touching down at 4:13 PM CDT and reaching 150 yards wide. It killed nobody, and did $50,000 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.
F040 to 72 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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 21, 2004
- Touchdown
- 4:13 PM CDT (21:13 UTC)
- Path length
- 1.7 miles (2.7 km)
- Path width
- 150 yards (137 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $50,000
- County
- Benton County
- Touchdown point
- 42.000, -91.900
- Lift-off point
- 42.000, -91.870
- Record number
- 366
What the Weather Service recorded
Tornado developed just west of 29th Avenue and dissipated just east of 29th Avenue. Path length was 1/8th of a mile long.
Tornado developed 0.1 miles West of the intersection of W26 and 69th Street. It moved Northeast and dissipated 0.2 miles Southeast of the intersection of 68th Street and 33rd Avenue. A few farms were damaged by the tornado with Bloomsbury Farms sustaining the heaviest damage. This included numerous trees twisted, substantial damage to the houses and outbuildings with one building completely destroyed.
Tornado briefly touched down south of Vinton near the intersection of 61st Street and Highway 218.
Rated F0
Rated F1 with winds estimated at 110 mph.
Rated F0
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
35 minutes of warning. NWS DVN issued a tornado warning for this county at 20:38 UTC, 35 minutes before the tornado touched down, in force until 21:15 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 20:27 UTC | 21:15 UTC | Severe Thunderstorm Warning | DVN |
| 20:38 UTC | 21:15 UTC | Tornado Warning | DVN |
| 21:14 UTC | 21:45 UTC | Tornado Warning | DVN |
| 21:43 UTC | 03:30 UTC | Flash Flood Warning | DVN |
| 21:44 UTC | 22:45 UTC | Severe Thunderstorm Warning | DVN |
| 21:48 UTC | 22:45 UTC | Tornado Warning | DVN |
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 20:02 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 surface observations
Cedar Rapids (CID), 19 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 19:52 UTC | 78 | 69 | 160° 12 kt | 1010.2 | HZ | |
| 20:35 UTC | 80.6 | 71.6 | 140° 12 kt | 19 | 1008.5 | TS |
| 20:52 UTC | 79 | 72 | 160° 11 kt | 1008.1 | TS | |
| 21:52 UTC | 80 | 68 | 200° 14 kt | 21 | 1007.8 | |
| 22:34 UTC | 66.2 | 64.4 | 20° 17 kt | 36 | 1010.2 | +RA BR |
| 22:41 UTC | 66.2 | 64.4 | 30° 18 kt | 27 | 1010.2 | -RA |
| 22:52 UTC | 66 | 63 | 70° 12 kt | 24 | 1009.8 |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Quad Cities radar (KDVN), 116 km away, was scanning. The volume nearest the touchdown began at 21:14 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) | Report | Where | County | Remark |
|---|---|---|---|---|
| 20:15 UTC | HAIL 1.25 | Traer | Tama, IA | |
| 20:16 UTC | HAIL 1 | Traer | Tama, IA | |
| 20:35 UTC | TSTM WND DMG | Evansdale | Black Hawk, IA | TREES DOWN ON LAFAYETTE ST. |
| 20:45 UTC | HAIL 0.88 | 1 Se Raymond | Black Hawk, IA | |
| 20:45 UTC | HAIL 0.88 | 4 Se Waterloo | Black Hawk, IA | ESTIMATED 4 MI SE OF WATERLOO, MM65, I380 |
| 21:10 UTC | TSTM WND DMG | 2 N Traer | Tama, IA | NUMEROUS TREES DOWN 1-2 MI NORTH OF TRAER |
| 21:16 UTC | HAIL 1 | Traer | Tama, IA | |
| 21:20 UTC | HAIL 0.88 | 2 Nw Dysart | Tama, IA | |
| 21:23 UTC | TSTM WND GST 60 | 3 N Clutier | Tama, IA |
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 21, 2004
23 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| May 21 | 2:28 PM CDT | F0 | Grundy, IA | 3.0 | 50 | |||
| May 21 | 2:38 PM CDT | F1 | Grundy, IA | 3.5 | 100 | $2,000 | ||
| May 21 | 2:49 PM CDT | F0 | Grundy, IA | 0.5 | 30 | |||
| May 21 | 4:02 PM EDT | F0 | Richland, OH | 0.0 | 0 | |||
| May 21 | 3:15 PM CDT | F0 | Grundy, IA | 0.5 | 40 | |||
| May 21 | 3:21 PM CDT | F0 | Black Hawk, IA | 0.3 | 30 | |||
| May 21 | 3:22 PM CDT | F0 | Grundy, IA | 0.5 | 40 | |||
| May 21 | 4:05 PM CDT | F0 | Benton, IA | 0.1 | 50 | |||
| May 21 | 4:07 PM CDT | F0 | Benton, IA | 0.1 | 50 | |||
| May 21 | 4:22 PM CDT | F3 | Linn, IA | 3.0 | 200 | $250,000 | ||
| May 21 | 4:44 PM CDT | F0 | Benton, IA | 0.0 | 50 | |||
| May 21 | 5:06 PM CDT | F1 | Jones, IA | 6.0 | 100 | $40,000 | ||
| May 21 | 5:12 PM CDT | F1 | Clay, IA | 1.0 | 200 | $230,000 | ||
| May 21 | 6:00 PM CDT | F1 | Pocahontas, IA | 5.0 | 300 | $30,000 | ||
| May 21 | 6:08 PM CDT | F2 | Pocahontas, IA | 12.5 | 880 | 15 | $2.5 million | |
| May 21 | 4:16 PM PDT | F0 | Spokane, WA | 0.2 | 70 | |||
| May 21 | 7:30 PM CDT | F0 | Wright, IA | 0.2 | 25 | |||
| May 21 | 9:14 PM EDT | F0 | Berkeley, WV | 3.0 | 1 | |||
| May 21 | 8:20 PM CDT | F1 | Pierce, NE | 1.5 | 150 | |||
| May 21 | 8:44 PM CDT | F0 | Brown, NE | 0.2 | 20 | |||
| May 21 | 9:20 PM CDT | F1 | Wayne, NE | 0.5 | 150 | |||
| May 21 | 9:20 PM CDT | F0 | Yankton, SD | 0.1 | 50 | |||
| May 21 | 10:13 PM CDT | F0 | Garfield, NE | 0.2 | 20 |
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.