EF1 tornado, Poplar City, Illinois, April 15, 2011

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

April 15, 2011

Touchdown

5:30 PM CDT (22:30 UTC)

Lifted

5:38 PM CDT (22:38 UTC)

On the ground

8 minutes

Path length

3.1 miles (5.0 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

1

Property damage

$300,000

County

Mason County

Touchdown point

40.213, -89.954

Lift-off point

40.258, -89.953

Record number

1104151630-01

12 damage points were recorded along this path by NWS ILX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 95 mph.

• .Three walls and roof of large shed blown down. Two shallow rooted trees uprooted.
• .Seven sections of an irrigation system tipped over.
• .One section of an irrigation system tipped over.
• .Three sections of an irrigagtion system tipped over.

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 interacting with an approaching cold front triggered severe thunderstorms across central and southeast Illinois during the afternoon and evening of April 15th. The airmass ahead of the front was moderately unstable and highly sheared. As a result, several supercell thunderstorms developed along and west of the I-55 corridor. The storms produced numerous funnel clouds and three confirmed tornadoes. Hail up to 2 inches in diameter was observed as well. The storms eventually congealed into a linear structure and weakened as they pushed into east-central and southeast Illinois during the mid to late evening.

A tornado touched down in a field about 6.5 miles west-southwest of Easton at 530 PM CDT. It knocked over an irrigation unit and damaged an outbuilding before traveling north and damaging several sheds, breaking windows, tearing roofing and siding off a house, and pushing a house a few inches off its foundation. One person was injured by flying glass. The tornado then damaged another outbuilding and several trees before dissipating 7 miles west-northwest of Easton at 538 PM CDT.

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

24 minutes of warning. NWS ILX issued a tornado warning for this county at 22:06 UTC, 24 minutes before the tornado touched down, in force until 22:45 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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:56 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), 53 km away, was scanning. The volume nearest the touchdown began at 22:30 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 2011 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

74 more were confirmed in the United States that day.

All 75 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.