EF0 tornado, (Eyw)Key West Inl Ar, Florida, August 11, 2017

1. EF065 to 85 mphthis tornado

   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 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

EF0

Date

August 11, 2017

Touchdown

5:03 PM EDT (21:03 UTC)

Lifted

5:05 PM EDT (21:05 UTC)

On the ground

2 minutes

Path length

0.2 miles (0.4 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

County

Monroe County

Touchdown point

24.569, -81.734

Lift-off point

24.568, -81.737

Record number

1708111503-01

7 damage points were recorded along this path by NWS KEY, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 65 mph.

• The examination of a video of the event and survey results revealed the first instance of damage to a hollow metal tube roof structure topped with plastic or hard vinyl covering, affixed to wood two-by-four supports of a fishing house shed just northwest of Safe Harbor on Stock Island. The roof structure was flipped airborne and deposited about 20 to 30 feet to the west-northwest of the original location.
• A hollow tubing boat covering frame, affixed with screws through flat plywood shims to another fish house shack, and used as a shade overhang, was removed as a single unit and deposited 20 feet to the east-northeast.
• A 15-by-15 foot folding tent structure topped with boat covering structure was lifted airborne for several seconds and destroyed 20 to 30 feet from its original location.
• The tornado moved just south of due west, and lifted a boat tarp including hollow tubing framework 30 to 40 feet in the air, depositing it in a stand of Austrailian Pine over 100 feet to the northwest.

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

A brief tornado was observed and recorded on video under a developing towering cumulus cloud line along the extreme Lower Keys.

The examination of a video of the event and survey results revealed the first instance of damage to a hollow metal tube roof structure topped with plastic or hard vinyl |covering, affixed to wood two-by-four supports of a fishing house shed just northwest of Safe Harbor on Stock Island. The roof structure was flipped airborne and deposited about 20 to 30 feet to the west-northwest of the original location. The tornado moved just south of due west, and lifted a boat tarp including hollow tubing framework 30 to 40 feet into the air, depositing it in a stand of Australian pines over 100 feet to the northwest. A 15-by-15 foot folding tent structure topped with boat covering structure was lifted airborne for several seconds and destroyed 20 to 30 feet from its original location. Another hollow tubing boat covering frame, affixed via screws through flat plywood shims to another fish house shack, and used as a shade overhang, was removed as a single unit and deposited 20 feet to the east-northeast. This direction of damage deposition was nearly opposite the direction of travel of the tornado. Numerous healthy small limbs of one half (0.5) inch diameter of healthy Australian pine were desposited toward the west-southeast across an unpaved dockfront access road. Video examinination determined some of the limbs were severed as the various roof covering structures struck the pine trees. It was at this point that the maximum wind estimate of 60 to 65 mph 3-second gust was demonstrated.||The tornado then entered the harbor waters at an oblique angle, causing a well-defined waterspout spray ring, and indicative of 3-second winds well in excess of 50 mph. The now-waterspout crossed back over land as a tornado at the docks south of the 4th Avenue curve on Stock Island, where loose objects aboard vessels was lifted and deposited in a small turning basin. Eyewitnesses and video indicated the tornado no longer lifted debris or spray at that point, and seemingly dissipated.

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.

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 General Thunderstorms Risk. The outlook in force was issued at 19:55 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.

Key West (EYW), 3 km from the path, in the two hours either side.

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

The Key West radar (KBYX), 5 km away, was scanning. The volume nearest the touchdown began at 21:02 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.

The live radar over the trackEvery 2017 tornado in FloridaEvery tornado in Florida since 1950Warnings in force in Florida nowThe forecast where you are

1 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.