A severe thunderstorm moving along a northbound outflow boundary produced isolated strong wind gusts over the center portion of the city of Key West.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS KEY wrote it up.
A severe thunderstorm moving along a northbound outflow boundary produced isolated strong wind gusts over the center portion of the city of Key West.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Key West, FL wrote its last area forecast discussion before the first event at Aug 20, 10:12 PM EST, 2 hours 33 minutes earlier.
Area Forecast Discussion National Weather Service Key West FL 1112 PM EDT Thu Aug 20 2020 .DISCUSSION... Water vapor imagery highlights an impressive mid-upper level trough across the Gulf of Mexico. The lift associated with this trough's eastern flank is well removed to the northwest of the Florida Keys. A small jet max is rounding the base this evening, so we will have to watch for any short wave undulations punching east into the subtropical ridge's real estate, which is entrenched across the Keys. The low-level ridging reaches west across the Straits of Florida. Satellite derived moisture products place drier air (1.6-1.8" PW) across the Cay Sal Bank and the Bahamas, and this air mass should advect our way overnight as the low-level ridge lifts north. The inherited forecast calls for 30% rain chances overnight, which is above the consensus but near normal. No updates planned or needed. && .MARINE... A high pressure ridge will build westward across the Florida Peninsula and eastern Gulf of Mexico tonight through Saturday. Meanwhile, Tropical Depression 14 will slide northwest through the Yucatan Peninsula. Consequently, breezes will freshen out of the east to southeast. Fresh to possibly strong east breezes will be possible by Saturday night as Tropical Depression Thirteen approaches from the east- southeast. Tropical Storm Conditions are possible Sunday night through Monday night in association with Tropical Depression 13. Confidence in the intensity forecast for poorly organized Tropical Depression Thirteen is low at this time. && .AVIATION... VFR and gentle southeast breezes will prevail at the EYW and MTH terminals overnight. && .PRELIMINARY POINT TEMPS/POPS... Key West 83 91 83 90 / 30 40 30 40 Marathon 83 92 83 91 / 30 30 30 40 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && Public/Marine/Fire...CLR Aviation/Nowcasts....SDR Data Acquisition.....DR Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest
Hazardous Weather Outlook National Weather Service Key West FL 657 AM EDT Thu Aug 20 2020 FLZ076>078-GMZ031>035-042>044-052>055-072>075-211100- Monroe Upper Keys-Monroe Middle Keys-Monroe Lower Keys- Florida Bay including Barnes Sound, Blackwater Sound, and Buttonwood Sound- Bayside and Gulf side from Craig Key to west end of Seven Mile Bridge- Gulf waters from East Cape Sable to Chokoloskee 20 to 60 NM out and beyond 5 fathoms- Gulf of Mexico including Dry Tortugas and Rebecca Shoal Channel- Gulf of Mexico from west end of Seven Mile Bridge to Halfmoon Shoal out to 5 Fathoms- Hawk Channel from Ocean Reef to Craig Key out to the reef- Hawk Channel from Craig Key to west end of Seven Mile Bridge out to the reef- Hawk Channel from west end of Seven Mile Bridge to Halfmoon Shoal out to the reef- Straits of Florida from Ocean Reef to Craig Key out 20 NM- Straits of Florida from Craig Key to west end of Seven Mile Bridge out 20 NM- Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal out 20 NM- Straits of Florida from Halfmoon Shoal to 20 NM west of Dry Tortugas out 20 NM- Straits of Florida from Ocean Reef to Craig Key 20 to 60 NM out- Straits of Florida from Craig Key to west end of Seven Mile Bridge 20 to 60 NM out- Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal 20 to 60 NM out- Straits of Florida from Halfmoon Shoal to 20 NM west of Dry Tortugas 20 to 60 NM out- 657 AM EDT Thu Aug 20 2020 This Hazardous Weather Outlook is for the Florida Keys and adjacent coastal waters. .DAY ONE...TODAY AND TONIGHT ...ALL RESIDENTS AND VISITORS IN THE FLORIDA KEYS SHOULD CLOSELY MONITOR THE LATEST FORECASTS ISSUED BY THE NATIONAL HURRICANE CENTER WITH RESPECT TO TROPICAL DEPRESSION THIRTEEN... Some thunderstorms may be strong on the waters in and around Dry Tortugas and southward early this morning, thereafter, only isolated thunderstorms are possible later on this morning and this afternoon. The primary thunderstorm hazards will be cloud to surface lightning strikes and gusty thunderstorm outflows. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Isolated to scattered thunderstorms will be possible along the island chain and the surrounding coastal waters. The primary thunderstorm hazards will be cloud to surface light strikes and locally gusty winds. Fresh to strong easterly breezes are possible over the marine waters from late Friday through Sunday. Small Craft Advisories may eventually be required later this weekend. However, tropical Storm conditions are possible along the Florida Keys and the surrounding coastal waters Sunday night through Monday night. Please stay tuned. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. APA APA
Special Weather Statement
National Weather Service Key West FL
128 AM EDT Fri Aug 21 2020
FLZ078-210600-
Monroe Lower Keys FL-
128 AM EDT Fri Aug 21 2020
...SIGNIFICANT WEATHER ADVISORY FOR KEY WEST, STOCK ISLAND, AND BOCA
CHICA UNTIL 200 AM EDT...
At 127 AM EDT, National Weather Service Meteorologists detected a
strong thunderstorm just south of Key West, moving north at 20 mph.
Wind gusts up to 50 mph and frequent to continuous lightning will be
possible with this storm.
Locations impacted include...
Key West, Big Coppitt Key, Boca Chica Channel Bridge, Boca Chica,
Fleming Key, Key Haven, Geiger Key, Sunset Key and Shark Key.
This includes US 1 between mile markers 0 and 12.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 2452 8188 2463 8192 2463 8190 2459 8189
2458 8184 2467 8179 2473 8168 2471 8164
2456 8163 2453 8171 2452 8176
TIME...MOT...LOC 0527Z 170DEG 18KT 2447 8175
WLCThe Key West radar (KBYX), 10 km away, was scanning. The volume nearest the first event began at 05:45 UTC.
1 thunderstorm wind. Local standard time, as filed.
A wind gust of 60 mph was measured at the rooftop of the National Weather Service Florida Keys in Key West.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2020Every state in 2020This day in weather historyWarnings in Florida, August 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 919741.