EF1 tornado, Okawville to Covington, Illinois, September 25, 2012

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mphthis tornado

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

3. EF2111 to 135 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. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 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

EF1

Date

September 25, 2012

Touchdown

5:23 PM CDT (22:23 UTC)

Lifted

5:29 PM CDT (22:29 UTC)

On the ground

6 minutes

Path length

4.0 miles (6.4 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

1

County

Washington County

Touchdown point

38.447, -89.543

Lift-off point

38.435, -89.471

Record number

1209251623-01

A strong cold front moved through the region, triggering showers and thunderstorms. There were numerous reports of large hail and damaging winds, as well as a tornado.

A tornado touched down near I-64 on the north side of Okawville where it blew an eastbound tractor trailer to the southwest into the median. The driver sustained minor injuries. The tornado travelled east and damaged a barn and other outbuildings at a farm along Illinois Route 177 about a quarter of a mile west of Cord Road. Roof panels were blown off, some large tree limbs blown down and several calf hutches blown about, some of which had calves in them. At Cord Road and Illinois Route 177, tin roof panels were blown off of another barn. About a quarter of a mile east of Cord Road, along Illinois Route 177, power lines were blown down, a small barn lost its roof and a mason block building was blown down. The tornado continued to move almost due east along Illinois Route 177 where it damaged a home at the intersection of IL Route 177 and Phobe Road. Roof shingles were blown off and several large tree branches were broken. One branch went through the roof of the garage and another damaged a car in the driveway. All of the damage so far was EF0. Near the intersection of Illinois Route 177 and County Road 4, the tornado destroyed a small barn. This damage was rated EF1 with a maximum wind speed of 100 mph. The tornado then turned a bit to the southeast and quickly dissipated over open fields. Overall, the path length was approximately 4 miles with a max path width of 100 yards.

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

4 minutes of warning. NWS LSX issued a tornado warning for this county at 22:19 UTC, 4 minutes before the tornado touched down, in force until 22:45 UTC.

The county was under a severe thunderstorm watch, issued at 22:05 UTC and running to 04:00 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, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:51 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.

Belleville - Scott AFB (BLV), 32 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The St Louis radar (KLSX), 106 km away, was scanning. The volume nearest the touchdown began at 22:22 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 2012 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois 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.