EF1 tornado, Webbers Falls Sheffi to Blackgum, Oklahoma, November 30, 2018

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

November 30, 2018

Touchdown

9:28 PM CST (03:28 UTC)

Lifted

9:37 PM CST (03:37 UTC)

On the ground

9 minutes

Path length

7.1 miles (11.4 km)

Path width

400 yards (366 m)

Deaths

0

Injuries

0

Property damage

$45,000

Counties

Muskogee and Sequoyah counties

Touchdown point

35.461, -95.113

Lift-off point

35.542, -95.037

Record number

1811302128-01

69 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 120 mph.

• portion of center pivot destroyed
• many trees snapped and uprooted
• multiple MH damaged/destroyed this area
• Roof of house and garage walls blown away

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

A strong low pressure trough translated from the southwestern United States into the Southern Plains on November 30th and December 1st. Warm and moist air had spread northward into eastern Oklahoma ahead of this system. Atmospheric instability became moderately strong during the afternoon and evening hours to the east of a cold front that was over western Oklahoma and south of a stationary front that was located across northern Oklahoma into southern Missouri. As the strong storm system moved into the Southern Plains on the 30th, wind fields throughout the atmosphere increased substantially, which resulted in very strong deep-layer and low-level wind shear across eastern Oklahoma during the evening and overnight hours.||Thunderstorms developed during the evening hours of the 30th across central and eastern Oklahoma. Moderately strong atmospheric instability across the area combined with very strong wind shear to produce organized severe thunderstorms, including supercells. Supercell thunderstorms produced several tornadoes and damaging thunderstorm wind gusts across eastern Oklahoma. One of the tornadoes was strong and exceptionally long-tracked, affecting Sequoyah, Cherokee, Adair, and Delaware Counties. A squall line moved rapidly across the area ahead of the surging cold front and produced additional tornadoes and damaging wind gusts.

This is the first segment of a two segment tornado. This tornado developed in the Arkansas River bottoms of far southeastern Muskogee County, where several center pivot irrigation systems were destroyed and barns were damaged. The tornado crossed the Arkansas River into Sequoyah County. Based on this damage, maximum estimated wind in this segment of the tornado was 80 to 85 mph.

This is the second segment of a two segment tornado. The tornado crossed the Arkansas River, moving into Sequoyah County, and uprooted trees as it crossed I-40. It continued to move northeast, crossing Highway 64 to the east of Gore where trees were snapped and a home was damaged. The tornado then dissipated over open country south of the E1000 Road. Based on this damage, maximum estimated wind in this segment of the tornado was 95 to 105 mph.

This is the first segment of a six segment tornado. This long-track tornado developed near Blackgum where homes were damaged, barns and outbuildings were destroyed, and trees were snapped. The tornado moved north-northeast, snapping and uprooting numerous trees as it approached an inlet of Lake Tenkiller, and crossed into Cherokee County. Based on this damage, maximum estimated wind in this segment of the tornado was 100 to 110 mph.

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

47 minutes of warning. NWS TSA issued a tornado warning for this county at 02:41 UTC, 47 minutes before the tornado touched down, in force until 03:30 UTC.

The county was under a tornado watch, issued at 23:23 UTC and running to 05:48 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. The outlook in force was issued at 00:57 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 Western Arkansas radar (KSRX), 69 km away, was scanning. The volume nearest the touchdown began at 03:28 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 2018 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

6 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.