F1 tornado, Ottumwa, Iowa, March 30, 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

March 30, 1998

Touchdown

5:35 PM CST (23:35 UTC)

Path length

0.2 miles (0.3 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

Property damage

$10,000

County

Wapello County

Touchdown point

41.020, -92.430

Lift-off point

41.020, -92.430

Record number

34

A strong cold front front extended from central Wisconsin across central Iowa into eastern Kansas during the early afternoon hours. There was a great contrast across the front with temperatures in the upper 70s to low 80s ahead of the front, with 30s and 40s behind the front. The air mass ahead of the front was quite unstable with surface dew point temperatures around 60 degrees. Deep moisture was in place across the state. An upper level disturbance moved northeast along the front and set off thunderstorms in the vicinity of the cold front. The storms raced northeast at nearly 60 MPH. The main weather threat with the storms was hail with numerous reports of three quarter to one inch diameter hail. Hail covered the ground south of Waterloo. Hail of nearly golf ball size fell just west of Des Moines near Waukee. Though there were gusty winds associated with the storms, very few locations reported severe winds. There were several reports of high winds over southeast Iowa. Most of the wind reports came from Wapello, Mahaska, and Davis Counties. One report of 60 MPH winds was received in Wapello County at Eddyville. Winds of 70 MPH were reported over eastern Davis County, where a barn was destroyed, and in Mahaska County where damage occurred in New Sharon. The line of storms did produce one tornado. The tornado touched down briefly west of Ottumwa, damaging a house there.

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 10:52 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 Des Moines radar (KDMX), 134 km away, was scanning. The volume nearest the touchdown began at 23:33 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 1998 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.