EF1 tornado, Keensburg to Allendale, Illinois, April 19, 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 19, 2011

Touchdown

9:53 PM CDT (02:53 UTC)

Lifted

9:56 PM CDT (02:56 UTC)

On the ground

3 minutes

Path length

2.8 miles (4.4 km)

Path width

125 yards (114 m)

Deaths

0

Injuries

0

Property damage

$50,000

County

Wabash County

Touchdown point

38.530, -87.787

Lift-off point

38.567, -87.767

Record number

1104192053-01

Thunderstorms organized into a bow echo that produced widespread very damaging winds and isolated tornadoes. A shortwave trough over the central and southern high Plains moved northeast through the Mid-Mississippi Valley into the upper Great Lakes. A surface low attendant to this system moved from west central Missouri northeast to north of St. Louis. The trailing cold front advanced southeast across the Lower Ohio Valley and served as the primary focus for thunderstorms.

Three steel towers carrying high-voltage power lines were bent or partially collapsed. A single wide mobile home was demolished. The frame was blown about 50 yards but was not bent. There was curvature in the debris field. A grain bin was blown one mile into a tree line, and three other grain bins were destroyed. Machine sheds were unroofed, with some walls collapsing. Barns were destroyed, and hundreds of trees were uprooted or snapped. Power poles were snapped. There was minor to moderate damage to house roofs. The tornado reached EF-2 intensity in sparsely populated areas. Where it crossed through the north and west part of Mount Carmel near the end of its path, the tornado weakened to EF-1 intensity. The damage in Mount Carmel consisted of numerous uprooted and snapped trees, moderate roof damage to at least 4 or 5 houses, and destroyed sheds. In the vicinity of where the tornado crossed Route 15, damage was minimal, consisting of just a few downed trees. Peak winds were near 125 mph. The average path width was about 100 yards.

A mobile home was rolled. Numerous large and mature trees were snapped and uprooted. Power poles were down. Siding was blown off a house. The well-defined path extended through dense cedar and pine groves, where nearly every tree was snapped or uprooted. A back porch was blown off. Peak winds were estimated around 110 mph.

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

18 minutes of warning. NWS PAH issued a tornado warning for this county at 02:35 UTC, 18 minutes before the tornado touched down, in force until 03:00 UTC.

The county was under a tornado watch, issued at 23:46 UTC and running to 06:15 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 Moderate Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 01:10 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.

Mount Carmel (AJG), 8 km from the path, in the two hours either side.

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

The Evansville,IN radar (KVWX), 32 km away, was scanning. The volume nearest the touchdown began at 02:54 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

69 more were confirmed in the United States that day.

All 70 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.