EF0 tornado, Orland Park, Illinois, August 4, 2008

1. EF065 to 85 mphthis tornado

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

2. EF186 to 110 mph

   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

EF0

Date

August 4, 2008

Touchdown

7:59 PM CDT (00:59 UTC)

Lifted

8:00 PM CDT (01:00 UTC)

On the ground

1 minutes

Path length

0.3 miles (0.5 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

Property damage

$30,000

County

Cook County

Touchdown point

41.644, -87.852

Lift-off point

41.642, -87.847

Record number

0808041859-01

A powerful line of thunderstorms moved across northern Illinois during the evening hours of August 4th. Widespread and significant wind damage was reported along with several brief tornadoes on the leading edge of this line of storms. Close to 550,000 customers lost power during these thunderstorms. In the City of Chicago, more than 4,400 trees suffered some amount of damage, 161 light poles were damaged and 252 power lines were blown down.

A tornado touched down along the south side of 135th Street, one block east of LaGrange Road. It moved southeast through the neighborhood along Howe Drive snapping off numerous tree tops, downing three or four large trees, blowing down a fence, sending a gazebo swirling 30 feet into the air before depositing it in a neighbor's yard and damaging a roof on an auto shop along Southwest Highway. A car was also damaged by a falling tree limb. At this point, the weakening tornado was wiped out by a microburst as it crossed the railroad trucks just east of Southwest Highway about a quarter mile south of 135th Street.

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

14 minutes of warning. NWS LOT issued a tornado warning for this county at 00:45 UTC, 14 minutes before the tornado touched down, in force until 01:15 UTC.

The county was under a severe thunderstorm watch, issued at 00:21 UTC and running to 02:49 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 22:44 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.

Chicago (MDW), 18 km from the path, in the two hours either side.

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

The Chicago radar (KLOT), 20 km away, was scanning. The volume nearest the touchdown began at 01:03 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 2008 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

7 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.