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EF0 tornado in Monroe County, Florida

Tornado August 11, 2017 · Monroe County, Florida

EF0
Rating
0.2 mi
Path length
25 yd
Path width
EF0EF1EF2EF3EF4EF5Unrated

The path drawn at its surveyed width of 25 yards (0.01 mi) — zoom in and the swath grows to true scale. Other tornadoes recorded nearby that day are shown faint.

What EF0 means. On the Enhanced Fujita scale, EF0 is light damage: shingles and siding peeled, gutters torn, branches broken, consistent with estimated gusts of 65–85 mph. The rating comes from a survey of the worst damage after the storm, not from a wind measurement, so it says as much about what the tornado hit as about how strong it was.

What the National Weather Service wrote

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.

The wider storm

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

Began near (eyw)key West Inl Ar (24.5688, -81.7339).

Source: NOAA Storm Events Database, event 721039. Narratives are written by the National Weather Service forecast office that issued the report.

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