F1 tornado, Independence, Iowa, April 23, 2001

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.

Rating

F1

Date

April 23, 2001

Touchdown

8:26 AM CDT (13:26 UTC)

Path length

5.0 miles (8.0 km)

Path width

220 yards (201 m)

Deaths

0

Injuries

3

Property damage

$1.0 million

County

Buchanan County

Touchdown point

42.470, -91.880

Lift-off point

42.500, -91.830

Record number

111

Summary for Independence tornado event on 4/23/01:The exit region of a vigorous mid-level jet streak helped create deep layer convergence in eastern Iowa along a surface cold front, during the morning of 4/23/01. The atmosphere was only marginally unstable, but shear values were very high. A study of the event at the NWS in the Quad Cities suggest that the tornado was non-descending in nature, with the rotation originating near the surface and building upward. Spotters reported no lightning or thunder with the tornado, which the local study suggests indicated rapid development during the initial stages of the storm. There was no evidence from radar data that a tornado occurred. The tornado touched down near the middle school in southwest Independence, and tracked through the west central and north central parts of the community, before lifting 3.5 miles northeast of Independence. The tornado path was continuous, 5 miles long and 1/8 mile wide. The tornado was rated F1 on the Fujita scale following a NWS Survey. Three people suffered minor injuries from flying debris, and were treated at the local hospital. Emergency management officials estimated the tornado caused a total of $ 1 million in damage. A total of 31 homes were damaged, two severely. 20 businesses and 20 vehicles were also damaged.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

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.

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 Storm Prediction Center had this point in a General Thunderstorms Risk. The outlook in force was issued at 12:41 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 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.

Oelwein (OLZ), 24 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 143 km away, was scanning. The volume nearest the touchdown began at 13:27 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.

The live radar over the trackEvery 2001 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

1 more were confirmed in the United States that day.

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.

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