F0 tornado, Soper, Oklahoma, May 11, 1999

1. F040 to 72 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. F173 to 112 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. F2113 to 157 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. F3158 to 206 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. F4207 to 260 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. F5261 to 318 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

F0

Date

May 11, 1999

Touchdown

8:30 PM CDT (01:30 UTC)

Path length

1.0 miles (1.6 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Property damage

$1,000

County

Choctaw County

Touchdown point

34.080, -95.700

Lift-off point

34.080, -95.700

Record number

1096

Summary of events for May 11 1999:Numerous severe thunderstorms formed along a slow-moving north-south cold front across eastern Oklahoma on the afternoon and evening of May 11. A cap of warm air in the mid-levels of the atmosphere kept thunderstorm activity suppressed until the first storm formed in Rogers and Mayes County late in the afternoon. This was the largest storm of the day as it showed strong rotation and produced very large hail to the size of baseballs.Many other severe thunderstorms formed and increased in coverage through the evening. With the slow movement of the cold front, many thunderstorms moved over areas already saturated by earlier thunderstorms, leading to localized flash flooding. Several brief tornadoes also formed through the evening, with the largest concentration in the Arkansas River valley between Muskogee and Sallisaw.

There was a brief tornado touchdown north of Soper, causing mostly tree damage.

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. One was issued for the county at another hour that day.

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. The outlook in force was issued at 01:32 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 live radar over the trackEvery 1999 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

7 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.