EF0 tornado, Anderson, Missouri, May 11, 2011

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

May 11, 2011

Touchdown

7:23 PM CDT (00:23 UTC)

Lifted

7:26 PM CDT (00:26 UTC)

On the ground

3 minutes

Path length

0.8 miles (1.3 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$10,000

County

McDonald County

Touchdown point

36.642, -94.422

Lift-off point

36.646, -94.409

Record number

1105111823-01

A linear convective complex stretching from northwestern Arkansas into Missouri pushed to the north northeast during the evening hours. The line of thunderstorms produced a few reports of downed trees due to thunderstorm wind gust as well as from a well defined outflow boundary that ran out ahead of the storm complex. Hail to the size of quarters was also reported in Pittsburg, Kansas from the system.

A National Weather Service damage survey team confirmed that an EF-0 tornado touched down to the east of Anderson in far southwest Missouri around 723 PM CDT Wednesday evening...and traveled approximately three quarters of a mile before lifting. Maximum width was approximately 75 yards wide.||Unlike tornadoes produced by supercells and normally located at the back edge of the storm...this tornado formed along the leading edge of a gust front ahead of a band of thunderstorms that had moved into western McDonald County. A few downed limbs east of the McDonald High School on Cedar Street provided the first indication of the severe event that would lead to a tornado that moved along Cedar Street from the Highway 71 Bridge to Mud Springs Road. ||A few shallow uprooted trees and numerous downed large limbs along the path indicated that maximum winds within the tornado were 70 to 80 mph. This was also consistent with damage to a barn as well as minor shingle damage to a house along the path. Winds appeared to be enhanced as the gust front crossed the Highway 71 underpass. Most of the tree debris at this point was laying to the east...though some larger trees were laying northeast to north indicating a convergent path.||The storm continued to down limbs eastward along Cedar Street...though turned sharply to the north at the intersection of Cedar and Mud Springs before lifting. Large limbs were downed to the east...north and west at this intersection...indicating a rotating debris pattern of a tornado. The tornado was further confirmed by an eyewitness who reported rotation as the storm approached Mud Springs Road.

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

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

The county was under a severe thunderstorm watch, issued at 21:04 UTC and running to 01:45 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 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:55 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 Springfield radar (KSGF), 112 km away, was scanning. The volume nearest the touchdown began at 00:22 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 MissouriEvery tornado in Missouri since 1950Warnings in force in Missouri nowThe forecast where you are

15 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.