F0 tornado, Corydon, Iowa, June 23, 2000

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

June 23, 2000

Touchdown

2:18 PM CDT (19:18 UTC)

Path length

0.2 miles (0.3 km)

Path width

20 yards (18 m)

Deaths

0

Injuries

0

Property damage

$1,000

County

Wayne County

Touchdown point

40.770, -93.320

Lift-off point

40.770, -93.320

Record number

254

A very unstable airmass was in place across Iowa during the morning of the 23rd. Thunderstorms erupted by the late morning hours as an upper level disturbance advanced into the state from the west. A small cluster of thunderstorms formed in as the mesoscale convective vorticity center from a round of convection over the high plains the previous night moved into air with CAPE values around 4000 J/kg. A warm front was lifting north across the state as well with surface dew points in the mid 70s to the south of the front. Although there were some reports of some small hail, less than in inch in diameter, from the storms; the main weather feature from these storms was high winds. The strongest winds occurred in Indianola as a microburst resulted in a wind gust of 109 MPH. High winds caused considerable tree damage and some building damage across south central Iowa as the cluster of storms moved east. A mobile home was knocked off of its foundation in the Moulton area as the storms moved through. One small tornado touched down briefly in Wayne County near Corydon. No significant damage was reported with this tornado. The same cluster of storms that moved across the far southern tier of Iowas counties produced high winds to the north of it. In Lucas County, strong south winds flowing out of the cluster caused damage on a farm near Chariton. A machine shed was destroyed with pieces of the building swept downwind for about one half mile.

Brief touchdown

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 16:58 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.

Chariton (CNC), 28 km from the path, in the two hours either side.

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

The Des Moines radar (KDMX), 112 km away, was scanning. The volume nearest the touchdown began at 19:18 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 2000 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

4 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.