EF1 tornado, White Bear to Hannibal Muni Arpt, Missouri, May 20, 2013

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

May 20, 2013

Touchdown

7:24 PM CDT (00:24 UTC)

Lifted

7:26 PM CDT (00:26 UTC)

On the ground

2 minutes

Path length

1.2 miles (1.9 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Marion County

Touchdown point

39.694, -91.449

Lift-off point

39.704, -91.431

Record number

1305201824-02

29 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 115 mph.

• Several small trees trunks snapped
• Several large limbs snapped and a few trees uprooted.
• Extra large pine tree snapped at the base, other medium to large branches down.
• Brick building. Part of roof torn off. Partial upper wall collapse.

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

A line of severe storms moved through the region. There were numerous reports of large hail and damaging winds, as well as a couple of tornadoes and flash flooding.

A tornado touched down west southwest of Hannibal, damaging several trees and a structure about a mile south of the Hannibal Regional Medical Center, just northeast of the intersection of Centerville Road and County Road 420. The tornado then moved northeast and caused its most intense damage, low end EF-1, at the intersection of Centerville Road and Shinn Lane. In this area several large trees were either uprooted or snapped off halfway up the trunk. The tornado moved northeast to Highway MM where it tore about a quarter of the tin roof off of a farm building and damaged some trees. The tornado dissipated as it crossed Highway MM.

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

22 minutes of warning. NWS LSX issued a tornado warning for this county at 00:02 UTC, 22 minutes before the tornado touched down, in force until 00:45 UTC.

The county was under a tornado watch, issued at 22:25 UTC and running to 01:55 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 19:58 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 St Louis radar (KLSX), 129 km away, was scanning. The volume nearest the touchdown began at 00:25 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 2013 tornado in MissouriEvery tornado in Missouri since 1950Warnings in force in Missouri nowThe forecast where you are

35 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.