EF1 tornado, Leach to Twin Oaks, Oklahoma, May 20, 2019

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, 2019

Touchdown

10:54 PM CDT (03:54 UTC)

Lifted

11:04 PM CDT (04:04 UTC)

On the ground

10 minutes

Path length

6.9 miles (11.1 km)

Path width

600 yards (549 m)

Deaths

0

Injuries

0

Property damage

$50,000

County

Delaware County

Touchdown point

36.204, -94.953

Lift-off point

36.221, -94.832

Record number

1905202154-01

116 damage points were recorded along this path by NWS TSA, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 115 mph.

• se of pt several chicken houses damaged

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

A strong upper level storm system moved into the Southern Plains from the Rockies on the 20th and 21st. The attendant warm front moved from northern Texas northward into northeastern Oklahoma during the day on the 20th, and then the cold front associated with this storm system moved through eastern Oklahoma during the late evening of the 20th and early morning hours of the 21st. Warm, moist, and very unstable air resided across eastern Oklahoma ahead of this system. This pattern resulted in multiple rounds of severe thunderstorms across eastern Oklahoma from the early afternoon of the 20th through late morning of the 21st. Very strong wind shear coexisting with the strong instability resulted in some supercell thunderstorms that produced large hail up to golfball size and multiple tornadoes on the 20th. A squall line developed along the cold front that moved into the area during the morning of the 21st, and that line of storms produced multiple tornadoes along the leading edge. Locally heavy rainfall and subsequent flash flooding occurred across northeastern Oklahoma as multiple rounds of thunderstorms affected generally the same area.

This is the second segment of a two-segment tornado. This large tornado moved into the far southwestern portion of Delaware County and moved northeast toward Leach. It damaged homes, destroyed outbuildings, and snapped or uprooted many trees. The tornado crossed the Cherokee Turnpike west of Twin Oaks and dissipated. Based on this damage, maximum estimated wind in this segment of the tornado was 110 to 120 mph.

This tornado damaged homes, destroyed outbuildings, and uprooted trees. It developed as the Peggs/Leach tornado was dissipating, and moved east-northeast across the end of the earlier tornado's path. Based on this damage, maximum estimated wind in the tornado was 85 to 95 mph.

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

13 minutes of warning. NWS TSA issued a tornado warning for this county at 03:41 UTC, 13 minutes before the tornado touched down, in force until 04:30 UTC.

The county was under a tornado watch, issued at 22:14 UTC and running to 05:19 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 Enhanced Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 01:17 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.

Tahlequah Municipal (TQH), 33 km from the path, in the two hours either side.

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

The Tulsa radar (KINX), 60 km away, was scanning. The volume nearest the touchdown began at 03:52 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 2019 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

38 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.