EF4 Norman–Lake Thunderbird tornado, Oklahoma, May 10, 2010

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 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 mphthis tornado

   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

EF4

Date

May 10, 2010

Touchdown

5:32 PM CDT (22:32 UTC)

Lifted

5:59 PM CDT (22:59 UTC)

On the ground

27 minutes

Path length

22.3 miles (35.8 km)

Path width

880 yards (805 m)

Deaths

1

Injuries

32

Counties

Cleveland and Pottawatomie counties

Touchdown point

35.181, -97.427

Lift-off point

35.255, -97.049

Record number

1005101632-01

A significant outbreak of severe thunderstorms and tornadoes affected a large part of northern, central, and southern Oklahoma. Tornadoes were most numerous across central and southern Oklahoma, with significant damage occurring over many areas. |Severe thunderstorms erupted by mid afternoon across northern and western Oklahoma. Given the potent combination of ingredients in place, storms began to produce tornadoes quickly after initiation. Storm motions of 50 to 60 mph were common.||During the mid afternoon hours, severe weather was confined to northern Oklahoma. It was there a long track supercell storm produced tornadoes near the Kansas border - including one rated EF3 - from near Wakita to north of Braman.||The capping inversion that had delayed thunderstorm development into central Oklahoma weakened, allowing for explosive supercell development along the dry line along and west of the Interstate 35 corridor. Rapid development and intensification was common with the late afternoon storms, with storms becoming tornadic within a very short time after initiation. This round of storms would directly impact a large part of the Oklahoma City metro area at rush hour, and posed a significant threat to the area. The first tornado in this area occurred in Canadian County.||During the next several hours, tornadoes were clustered around the metro area, and at times there were multiple significant damaging tornadoes occurring simultaneously. Several of the tornadoes had long tracks. Damage from the tornadoes was substantial, with numerous structures, vehicles, trees and power poles/lines significantly damaged or destroyed. One of the more intense tornadoes moved across Lake Thunderbird east of Norman destroying numerous boats.||More storms developed across southwest and south central Oklahoma, and also quickly became tornadic. ||By 9 pm, 35 tornadoes had been reported. While the loss of three lives was tragic, the casualties could have been much higher given the storm's fast motions, their intensity, the time of day and the areas impacted. ||While exact monetary damage figures were not available, it is estimated that losses were in excess of $595 million. At least 450 sustained injuries, most of them minor. Unfortunately three people lost their lives. ||Note: The large number of injuries and tornadoes made it difficult to associate injuries with specific tornadoes. Injury numbers were included when we had confidence in the numbers. ||Note: The complex nature of storm evolutions and interactions made the job of classifying tornadoes difficult. This represents our best scientific assessment based on ground and aerial surveys, data from multiple radars, photographic and video evidence and anecdotal information.

This tornado is labeled I1. This long-tracked and devastating tornado developed west of I-35, northwest of Max Westheimer airport. Widespread tree, power line/pole damage was reported from near I-35 to the east side of Stanley Draper Lake. Several homes also sustained damage, mainly with mostly roofs receiving significant damage, and some siding was ripped off. Several fences were also knocked down as the tornado moved northeast. From the east side of Lake Stanley Draper, near Hiwassee Road and SE 89th Street, to just south of Harrah, the damage path became more severe and focused. The tree damage became more severe, breaking at various heights of the tree or being uprooted. Walls of homes collapsed, and debris from the homes scattered in all directions. Several 2x4's punctured roofs and ceilings over numerous structures. A few mobile homes in this area were also completely destroyed. Where the tornado crossed I-40, a gas station and drive-in restaurant sustained up to EF3 damage. The most severe damage, one of the two EF4 tornadoes of the day, occurred in the Deerfield West Subdivision. A well-built residence here was completely destroyed, with most exterior and interior walls collapsing. The tornado finally lifted 2 miles south of Harrah. In addition to the incredible damage, one person lost their life while trying to flee the tornado.

This tornado is labeled #J1, and moved into Pottawatomie County near state highway 9. The tornado a few hundred yards east of the National Weather Center in Norman, Oklahoma. The damage intensity increased gradually along the path with significant damage beginning as the tornado approached Lake Thunderbird. This tornado crossed Lake Thunderbird, severely damaging two campgrounds and the marina where about 300 boats were docked. The most severe damage occurred from the Little Axe School to the Cleveland/Pottawatomie county line. Trees were stripped of some bark and branches. Large objects were thrown considerable distances, including some concrete pillars. The metal bleachers near the school were tossed or rolled several hundred yards. Some appliances were also lofted as a dryer was found about 50 feet up in a tree. Considerable structural damage also occurred, as some foundation homes were mostly destroyed. In addition to the damage, one person lost their life as a result of the tornado.

This tornado is labeled #L1. The tornado developed near the junction of Walker and Ingram Roads, causing major damage to home and damaging several trees. The tornado crossed to the east side of the lake, downing high tension power lines and another residence. The tornado grew to its widest near Highway 102. Another home, a mobile home, and barn were severely damaged just east of the highway. Metal poles that were embedded in concrete at the barn were ripped out of the ground with the concrete still attached. A 80,000 pound box car was rolled about 300 yards. A few trees that were damaged were debarked. The tornado lifted south of Interstate 40.

This tornado lasted for at least 30 miles and continued into Seminole and Okfuskee counties, with significant damage along almost its entire path. At times, the tornado damage path widened up to a mile. The most significant damage was located north and northeast of Earlsboro near the Pottawatomie/Seminole county border. Here a two story home was destroyed except for a few interior walls. A pick-up truck was also lofted approximately a quarter of a mile, and a semi-trailer was lofted or rolled approximately 200 yards. Farther east along its path, seven high tension towers were downed. Significant tree damage was reported along the entire track of the tornado, some of them debarked and stripped off all their branches. This tornado is labeled #J4.||This tornado moved into Seminole County.

The deaths

1 direct deaths are recorded for this tornado, each with what Storm Data knows of it.

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

45 minutes of warning. NWS OUN issued a tornado warning for this county at 21:47 UTC, 45 minutes before the tornado touched down, in force until 22:45 UTC.

The county was under a tornado watch, issued at 18:25 UTC and running to 02:29 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 19:59 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.

Norman/Westheimer (OUN), 21 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Norman radar (KTLX), 13 km away, was scanning. The volume nearest the touchdown began at 22:31 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 2010 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

70 more were confirmed in the United States that day.

All 71 of them

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.