F2 tornado, Sepo to Buzzville, Illinois, April 7, 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

April 7, 1998

Touchdown

6:04 PM CDT (23:04 UTC)

Path length

11.0 miles (17.7 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

Counties

Mason and Fulton counties

Touchdown point

40.330, -90.070

Lift-off point

40.430, -89.880

Record number

906

A tornado initially touched down in a farm field and overturned some irrigation equipment 3 miles east southeast of Sepo. Then it travelled to the northeast destroying a mobile home which was anchored, but the only thing left was the floor of the unit. The floor was wiped clean of all plumbing fixtures and walls with only a washing machine and water heater left on the floor. Most of the debris was deposited in the Illinois River about 50 yards away. A couple of three foot diameter trees were snapped off near the mobile home. Also, a nearby machine shed was destroyed and a motor home was rolled three times over the top of the damage and left upside down 30 feet from its original position. Just north of the mobile home, a concrete block pumping station was damaged. The roof was torn off, all of the windows broken out, and one wall was buckled. The tornado then moved across the Illinois River into Mason County. The tornado moved into the Baldwin Beach area, damaging three homes. From there the tornado, hopped and skipped along a northeasterly track, causing spotty damage to trees. The tornado finally lifted and dissipated 7 miles northeast of Buzzville in the Jake Wolf Memorial Fish Hatchery area. No injuries were reported and no damage estimate was available.

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

13 minutes of warning. NWS ILX issued a tornado warning for this county at 22:51 UTC, 13 minutes before the tornado touched down, in force until 00:00 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 10:48 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 Lincoln radar (KILX), 60 km away, was scanning. The volume nearest the touchdown began at 23:06 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 IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois 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.