EF1 tornado, Mt Vernon to Bluford, 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

9:03 PM CDT (02:03 UTC)

Lifted

9:07 PM CDT (02:07 UTC)

On the ground

4 minutes

Path length

4.3 miles (6.9 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Property damage

$70,000

County

Jefferson County

Touchdown point

38.348, -88.935

Lift-off point

38.380, -88.868

Record number

1104192003-01

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

• .Roof of an attached workshop or garage on the south side of the house was uplifted and thrown to the northwest. Additional damage to the roof of the house. Large healthy trees were uprooted and found in a convergent pattern on this and neighboring properties. At least one 2x4 was driven into the north side of the roof. Debris was found in front of the house and in the open field to the north (across highway 161).
• .TV antenna was bent over the chimney towards the northwest. Trampoline on the south side of the house in the backyard was carried to the north (across highway 161) and severely mangled. The trampoline was thrown back to the northwest.
• .Several trees uprooted south of the house and and one or two had been topped. Convergent pattern noted in the tree damage among neighboring properties.
• .All walls collapsed on a brand new pole barn.

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

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.

There was shingle damage to houses. Awnings and overhangs were destroyed. Many trees were snapped or uprooted. In the immediate vicinity of the tornado damage path, straight-line winds from the same storm damaged the roof and chimney of a house. Peak winds were around 105 mph. The average path width was 90 yards.

Many trees were snapped or uprooted. A hay barn was partially pushed over. An old wooden barn was destroyed. A newer wood-frame equipment shed was nearly destroyed. A house roof was heavily damaged, with loosening of roof decking. In the immediate vicinity of the tornado, straight-line winds from the same storm caused a large tree to fall on the roof of a house. Peak winds were near 110 mph. The average path width was 80 yards.

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

10 minutes of warning. NWS PAH issued a tornado warning for this county at 01:53 UTC, 10 minutes before the tornado touched down, in force until 02:30 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 Vernon (MVN), 6 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), 103 km away, was scanning. The volume nearest the touchdown began at 02:04 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.