F2 tornado, Austinville to Waverly, Iowa, June 27, 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 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. F2113 to 157 mphthis tornado

   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

F2

Date

June 27, 1998

Touchdown

10:23 PM CDT (03:23 UTC)

Path length

25.5 miles (41.0 km)

Path width

80 yards (73 m)

Deaths

0

Injuries

0

Property damage

$10,000

Counties

Butler and Bremer counties

Touchdown point

42.580, -92.930

Lift-off point

42.700, -92.480

Record number

1108

Iowa was located in the warm sector of a developing storm system to the west. The warm front had moved to the northern Iowa border during the afternoon of the 27th with dew point temperatures in the mid 70s to around 80 blanketing the state in the warm sector. Initially, the airmass was capped, preventing thunderstorms from forming during the afternoon. Slightly cooler air moved in during the evening hours. In addition to the slightly cooler air moving in aloft, a cold front was poised over eastern Nebraska ready to move east into the state. Thunderstorms erupted rapidly by early evening with hail and high winds reported over northern Iowa. There were numerous reports of hail of an inch or larger in diameter, with a few reports of golf ball size hail. High winds were also a problem with many of the storms producing 60 to 70 MPH wind gusts. Reports of tree and power line damage were widespread. There were a few tornadoes as well. One tracked across open country in Cerro Gordo County before damaging a house south of Clear Lake. Another tornado touched down near Swaledale in Cerro Gordo County and passed southeast of Mason City. Much of the track was over open country, however one house was destroyed near Swaledale by this tornado. The longest track tornado moved across Butler and Bremer Counties. It also passed through open country, causing damage to crops and out buildings. In addition to these, there were a few brief touchdowns reported. Iowa soil remained very saturated with numerous rivers at or near flood stage. Heavy rainfall of near 4 inches in a couple hours time caused flash flooding in Cerro Gordo County. A widespread area of north central into northeast Iowa received heavy rainfall. Many areas picked up two to four inches of rain in a few hour period. This resulted in urban and small stream flooding, and ultimately general river flooding in the days that followed. As the storms moved through Worth County, lightning struck an outbuilding west of Kensett. The building was set on fire and destroyed.

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

15 minutes of warning. NWS DMX issued a tornado warning for this county at 03:08 UTC, 15 minutes before the tornado touched down, in force until 03:40 UTC.

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 10:56 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 1998 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

32 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.