F0 tornado, West Des Moines, Iowa, July 24, 2001

1. F040 to 72 mphthis tornado

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

2. F173 to 112 mph

   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

F0

Date

July 24, 2001

Touchdown

4:36 PM CDT (21:36 UTC)

Path length

0.2 miles (0.3 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

County

Polk County

Touchdown point

41.520, -93.720

Lift-off point

41.520, -93.720

Record number

235

Iowa continued to be in a very unstable airmass with temperatures in the 80s and dew point temperatures well into the 70s. A mesoscale vorticity maximum developed over the High Plains during the previous night and was located over northeast Nebraska during the morning of the 24th. A complex of thunderstorms continued to move east into northwest Iowa. As daytime heating continued, the storms became stronger and more organized. The main product into the early afternoon hours was heavy rainfall. During the early to mid afternoon hours, meso analysis clearly indicated the development of a surface low pressure system. As the outflow, or meso cold front, dropped southeast into southern Iowa it encountered very rich air with dew points in the low 80s. Thunderstorms developed explosively in central Iowa. Within 15 to 20 minutes of initial development the storms became severe. A tornado touched down in an open field in southern Polk County, about 5 miles south of West Des Moines. The tornado was not well organized and did little damage. Most of the storms that became severe produced high winds. Winds of 65 MPH were reported in the Waterloo area. One cell produced a wet microburst southeast of the city of Waterloo with winds around 80 MPH. The high winds ripped the roof off of a house there, resulting in the house being toppled. The storms left 2.29 inches of rain officially in the city, though some areas unofficially reported in excess of 8 inches. Considerable urban flooding took place in the city of Waterloo, with flash flooding in the outlying areas. Many basements were flooded as reports of standing water nearly 3 feet deep in the streets were received. Earlier in the afternoon heavy rains fell in Webster City. Upwards of 2 inches of rain fell in under an hour causing urban flooding in the city. The water receded quickly after the rain stopped. High winds were also reported in Story County in the Ames area. A few reports of hail were received, but the hail was not all that large being as the freezing level was 15000 feet. Nickle size hail fell in Waterloo and also in Windsor Heights. After the initial fury of activity, the storms did not produce severe weather for a few hours. As the storms continued to move east, they picked up in intensity again in the Ottumwa area. Winds of 60 to 70 MPH blew through Ottumwa and continued east toward the Agency area.

Brief touchdown in field south of town.

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 Slight Risk. The outlook in force was issued at 20:15 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.

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

2 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.