EF1 tornado, Monroe City Regnl Ar, Missouri, June 27, 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

June 27, 2011

Touchdown

1:05 AM CDT (06:05 UTC)

Lifted

1:08 AM CDT (06:08 UTC)

On the ground

3 minutes

Path length

0.4 miles (0.7 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

County

Monroe County

Touchdown point

39.605, -91.741

Lift-off point

39.601, -91.735

Record number

1106270005-01

A powerful complex of thunderstorms, known as a bow echo, moved across Missouri and Illinois during the late evening hours of June 26th and early morning hours of June 27th. The line, which raced east at 60 to 70 mph, produced widespread winds of 40 to 60 mph along and north of Interstate 70. Storm assessment teams from the National Weather Service in St. Louis evaluated the most intense damage which occurred over northeast Missouri and west central Illinois. From the extreme damage that occurred in localized areas, it appears that wind speeds reached 70 to 100 mph. The extensive nature of the damage caused power outages to at least 55,000 customers. Some did not have power return until Tuesday night. Also, there were several reports of flash flooding, especially over northeastern Missouri due to the already saturated soils from previous rains over the past week.

A tornado touched down about 3.5 miles south of Monroe City on the west side of U.S. Highway 24 and travelled to the southeast, crossing the highway before lifting and dissipating along County Road 591. There was significant tree damage along the path. Trees were 60 to 80 feet tall with trunk diameters of 3 to 4 feet. Some of the trees were snapped a third to half way up. Other large trees were uprooted. Some of the large tree limbs were tossed 50 to 70 yards to the east southeast. The total path length was four tenths of a mile and the max width was 40 yards. The tornado was rated an EF1.

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

10 minutes of warning. NWS LSX issued a tornado warning for this county at 05:55 UTC, 10 minutes before the tornado touched down, in force until 06:15 UTC.

The county was under a tornado watch, issued at 23:55 UTC and running to 06:33 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 05:59 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), 136 km away, was scanning. The volume nearest the touchdown began at 06:04 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 MissouriEvery tornado in Missouri since 1950Warnings in force in Missouri nowThe forecast where you are

4 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.