EF1 tornado, Madill to Milburn, Oklahoma, April 14, 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 14, 2011

Touchdown

6:03 PM CDT (23:03 UTC)

Lifted

6:25 PM CDT (23:25 UTC)

On the ground

22 minutes

Path length

14.0 miles (22.5 km)

Path width

300 yards (274 m)

Deaths

0

Injuries

0

Counties

Marshall and Johnston counties

Touchdown point

34.130, -96.790

Lift-off point

34.200, -96.570

Record number

1104141703-01

An upper level trough moved onshore along the west coast on the 13th, and continued east toward the plains. The storm system strengthened as it moved east of the Rocky mountains, eventually becoming a major storm system, with blizzard conditions on the west and north sides of it, and powerful thunderstorms to the south and east. A surface low pressure moved from the Texas panhandle into southern Kansas, with a dry line extending to the south. The dry line moved quickly east before slowing to the east of I-35 in Oklahoma. Dew point temperatures reached the middle 60s east of the dry line, with bone-dry conditions advecting in on the back side of the dry line. The cap that was in place was all but erased by mid afternoon, and thunderstorms quickly developed over eastern Oklahoma. The wind shear in place was more than sufficient for rotating thunderstorms, with most storms become supercells. Very large hail and wind damage was common early in the thunderstorm life cycle. A weak tornado developed northwest of Stroud, with other storms showing signs of rotation by late afternoon. Additional tornadoes developed through the early evening, with a couple of them doing damage. The tornadoes were in addition to the hail up to softball size. By late evening, at least five tornadoes were reported, with one of them rated and EF-3.

This tornado began three miles north-northwest of Madill and continued northeast into Johnston county. It finally lifted three miles south-southwest of Milburn. Damage was reported to several structures, with widespread tree/power pole/line damage. Monetary damages estimates were not available.

This tornado was a continuation of the tornado that began 3 NNW of Madill in Marshall County. It continued to produce tree damage after crossing Lake Texoma into southern Marshall County.

Two off-duty NWS employees observed this tornado to the south of the tornado that moved from northeast of Madill to SSW of Milburn. No known damage occurred and the tornado location was estimated.

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

34 minutes of warning. NWS OUN issued a tornado warning for this county at 22:29 UTC, 34 minutes before the tornado touched down, in force until 23:15 UTC.

The county was under a tornado watch, issued at 19:28 UTC and running to 02:07 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 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:28 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 Norman radar (KTLX), 141 km away, was scanning. The volume nearest the touchdown began at 23:03 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 OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

47 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.