EF1 tornado, Toronto to Mechanicsburg, Illinois, August 19, 2009

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

August 19, 2009

Touchdown

3:17 PM CDT (20:17 UTC)

Lifted

3:37 PM CDT (20:37 UTC)

On the ground

20 minutes

Path length

12.9 miles (20.8 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

Property damage

$200,000

Crop damage

$240,000

County

Sangamon County

Touchdown point

39.705, -89.615

Lift-off point

39.780, -89.392

Record number

0908191417-01

30 damage points were recorded along this path by NWS ILX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF3. The highest wind the damage implies is 145 mph.

• Wide swath of corn field flatted. See evidence of strong inflow.
• two grain buildings, gone. back into flat corn field... track back up to house where it busted up the tree line. and an outbuilding...
• Center of tornado track crossing road
• Southern edge of path. Corn field flattened.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

A vigorous upper-level disturbance in conjunction with a warm front lifting northward through central Illinois triggered strong to severe thunderstorms during the afternoon and evening of August 19th. Embedded supercells within a long line of storms produced enhanced wind damage and tornadoes. Seven tornadoes touched down on August 19th, affecting parts of Scott, Morgan, Sangamon, Logan, DeWitt, McLean, and Vermilion counties. The strongest tornado was rated as an EF3 by an NWS Storm Survey as it tracked across southern Logan County. Total damages to crops and property from the 7 tornadoes were estimated to be more than $25 Million.

The tornado touched down 6 miles south-southeast of Springfield on the west banks of Lake Springfield at 217 PM CST. The tornado then crossed the lake and continued northeastward just southeast of Rochester before lifting 2 miles south-southeast of Mechanicsburg at 237 PM CST. Several large trees were snapped off along the west shore of Lake Springfield as the tornado first touched down. Numerous trees and tree branches were knocked down further east along the path of the storm, with a few structures damaged by falling limbs, including the Lake Springfield Yacht Club. In addition, widespread crop damage was observed.

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

27 minutes of warning. NWS ILX issued a tornado warning for this county at 19:50 UTC, 27 minutes before the tornado touched down, in force until 20:30 UTC.

The county was under a tornado watch, issued at 17:51 UTC and running to 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, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 21:34 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), 48 km away, was scanning. The volume nearest the touchdown began at 20:18 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 2009 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

29 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.