F1 tornado, Anita, Iowa, May 21, 1998

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

May 21, 1998

Touchdown

9:20 PM CDT (02:20 UTC)

Path length

0.5 miles (0.8 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

Property damage

$70,000

County

Cass County

Touchdown point

41.470, -94.770

Lift-off point

41.470, -94.770

Record number

248

A frontal boundary remained nearly stationary to the south of Iowa. Thunderstorms fired up as warm air over ran the cooler air at the surface. Storms formed over Nebraska and moved into western Iowa during the mid evening hours, then continued to advance east across the state. For the most part the storms produced high winds with wind gusts to 70 MPH or more at times. Winds gusted to 77 MPH west of Greenfield in Adair County. There were numerous reports of trees and power lines downed. One injury occurred in Union County as campers were overturned at Green Valley State Park by the high winds. Another injury occurred in Cass County when 65 to 80 MPH winds blew through. Three semi-tractortrailers and one car were overturned by high winds in Interstate 80. There were also many reports of farm sheds and buildings being damaged or destroyed by the winds. Some building damage was reported in Creston. A barn and farm shed was destroyed by high winds in Wayne County near Seymour. Early in the storms development, a small tornado touched down in Cass County north of Anita. The tornado destroyed several sheds and grain bins there. In addition to the wind, there were numerous reports of marble size hail. Hail was not a major event with these storms however. The only large hail reports came early on in the event with golf ball size hail at Brayton in Audubon County, and one inch diameter hail reported in Cass County northwest of Atlantic.

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.

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 10:39 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.

Atlantic (AIO), 24 km from the path, in the two hours either side.

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

The live radar over the trackEvery 1998 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

14 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.