F1 tornado, Wyoming to Whitefield, Illinois, April 20, 2004

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

April 20, 2004

Touchdown

5:05 PM CDT (22:05 UTC)

Path length

10.8 miles (17.4 km)

Path width

440 yards (402 m)

Deaths

0

Injuries

0

Property damage

$260,000

Counties

Stark, Marshall and Bureau counties

Touchdown point

41.070, -89.650

Lift-off point

41.170, -89.480

Record number

826

Tornado formed 0.4 miles northwest of Camp Grove in Marshall county (WFO ILX) at 1606 CST and traveled northeast and entered Southern Bureau County at 1617 CST 0.5 miles West of Whitefield. The tornado dissipated at 1619 CST 1.2 miles northeast of Whitefield near the intersection of 50 North/1925 East. In Bureau County, the tornado was on the ground for 1.7 miles and had a width of 100 yards. A farmstead near county roads 00 N and 1775 E, West of Whitefield, had a barn and several outbuildings damaged with damage to the roof of the farmhouse.

A tornado touched down 6.5 miles east of Wyoming (Stark County). As it traveled east, it blew out 5 windows on a house and damaged the roof of a barn. Also, numerous trees were either uprooted or snapped off. The tornado then crossed from Stark County into Marshall County 7.3 miles east northeast of Wyoming. No injuries were reported.

The tornado crossed from Stark County into Marshall County four tenths of a mile northwest of Camp Grove. It initially blew down numerous trees and power lines until it reached the intersection of 1300N and 250E where it destroyed a shed and a pole barn which had farm equipment in it. The farm equipment was damaged with damage estimated around $250,000. It then continued moving northeast blowing a grain bin into a field, blew down more trees and power lines then crossed into Bureau County (WFO DVN county warning area) west of Whitefield. No injuries were reported.

Rated high end F0

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 General Thunderstorms Risk. The outlook in force was issued at 19:58 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.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2004 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

31 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.