F1 tornado, Pontiac to Cullom, Illinois, May 30, 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

May 30, 2004

Touchdown

6:11 PM CDT (23:11 UTC)

Path length

12.0 miles (19.3 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Livingston County

Touchdown point

40.780, -88.720

Lift-off point

40.820, -88.550

Record number

964

The morning of May 30 started out with a line of showers and thunderstorms moving into north-central Illinois. Other thunderstorms developed over portions of east central Illinois and northwest Indiana. The major threat was heavy rain which produced widespread street flooding. There were also reports of thunderstorm wind damage. The line of thunderstorms continued to march east through northeast Illinois and northwest Indiana and by early afternoon the line had pushed east of the region. By mid afternoon a second line of thunderstorms crossed the Mississippi river into western Illinois and other storms developed over east central Illinois and northwest Indiana. The storms continued to move through the area into early evening. The two lines of thunderstorms produced widespread tree damage. There were also a few reports of lightning damage associated with these storms. Flash flooding was a serious problem as a considerable amount of rain had fallen recently in addition to heavy rains associated with these storms. The storms produced several weak tornadoes over Livingston County Illinois.

This event was a series of short tornado segments south of Pontiac. It began 8 miles southwest of Pontiac near County Roads 1400 North and 900 East. A barn roof was torn off and a large tree was snapped near 1000 East. Trees and limbs were blown down and farm outbuildings were damaged along County Road 1400 North. The damage ended at Pike Creek about one half mile west of 1200 East, where doors of a shed were blown out. Additional damage began just east of Interstate 55, north of County Road 1400 North. Trees and limbs were down at County Road 1325 East and near a nursing home on Old Route 66. Damage occurred again near County Road 1700 East, north of County Road 1400 North, where a house had roof damage and trees were blown down. Tree limbs were damaged on County Roads 1775 East and 1800 East. The most intense damage was on Billet Rd., about 1/2 mile north of County Road 1400 North, near the Vermillion River. About 1 dozen large trees were snapped in this area. The damage path was up to 50 yards wide at this point and the tornado was rated F1. The damage ended near County Roads 2000 East and 1500 North, where an old barn was blown down. This is 5 miles southeast of Pontiac. The total path was 12 miles.

An experienced storm spotter and chaser reported a tornado 6 miles southwest of Dwight. Trees were damaged in this area. It had a brief narrow path.

A trained spotter reported and photographed a tornado west of Saunemin. Trees were knocked down on the north side of State Road 116 near 2500 East, about 3 miles west of Saunemin.

A brief, narrow tornado occurred along a 1 mile path on County Road 1700 North, from County Road 3100 East to about 3200 East. This is about 3.5 to 2.5 miles west of Cullom. There was minor damage to trees and a farm building.

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

48 minutes of warning. NWS LOT issued a tornado warning for this county at 22:23 UTC, 48 minutes before the tornado touched down, in force until 23:30 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 High Risk, with a 0.25 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 16:38 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), 93 km away, was scanning. The volume nearest the touchdown began at 23:09 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.

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

80 more were confirmed in the United States that day.

All 81 of them

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.