130  
NOUS42 KKEY 121918  
PNSKEY  
FLZ076>078-131800-  
 
PUBLIC INFORMATION STATEMENT  
NATIONAL WEATHER SERVICE KEY WEST FL  
315 PM EDT SAT AUG 12 2017  
   
..NWS DAMAGE SURVEY FOR 08/11/2017 TORNADO EVENT
 
 
   
OVERVIEW
 
 
ON AUGUST 11, 2017 SHORTLY AFTER 5:00 PM EDT, DAMAGE TO FISH HOUSE  
SHED ROOF STRUCTURES AND BOAT COVERINGS WAS OBSERVED IN ASSOCIATION  
WITH A TORNADO NEAR THE WORKING WATERFRONT TO THE NORTHWEST OF SAFE  
HARBOR, STOCK ISLAND, FLORIDA. PER EXAMINATION OF DOPPLER RADAR DATA  
FROM KBYX (BOCA CHICA KEY), THE TORNADO MAY HAVE INITIALLY DEVELOPED  
AS PART OF A NARROW LANDFALLING WATERSPOUT OR BRIEF LANDSPOUT  
CIRCULATION.  
 
   
TORNADO
 
 
RATING: EF-0  
ESTIMATED PEAK WIND: 60-65 MPH  
PATH LENGTH /STATUTE/: 0.2 MILES  
PATH WIDTH /MAXIMUM/: 25 YARDS  
FATALITIES: 0  
INJURIES: 0  
 
START DATE: AUG 11 2017  
START TIME: 5:03 PM EDT  
START LOCATION: 3 ENE KEY WEST  
START LAT/LON: 24.57/-81.73  
 
END DATE: AUG 11 2017  
END TIME: 5:05 PM EDT  
END LOCATION: 3 ENE KEY WEST  
END_LAT/LON: 24.57/-81.74  
 
SURVEY SUMMARY: 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 IN 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.  
 
ADDITIONAL SURVEY OF ADJACENT PROPERTIES AND A LARGE CAMPGROUND ON  
THE BOCA CHICA CHANNEL WATERFRONT TO THE EAST OF THE AREA OF IMPACT  
REVEALED NO VISUAL CLUES OF TORNADO IMPACT OR LANDFALLING WATERSPOUT.  
UPDATES TO THIS SURVEY MAY BE REQUIRED IF ADDITIONAL INFORMATION  
IS OBTAINED.  
 
NOTE: THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT  
TO CHANGE PENDING FINAL REVIEW OF THE EVENT AND PUBLICATION IN NWS  
STORM DATA.  
 

 
 
JR  
 
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