Hurricanes rarely hit Key West but on October 24, 2005, we experienced the worst storm in
memory - Hurricane Wilma. The entire island was told to evacuate. Business owners put up
their hurricane protective shutters and plywood. After the hurricane had passed, the storm surge
sent 8’ of water inland, literally putting most of the Lower Keys and Key West underwater. Sixty
percent of the homes in Key West were flooded and the surge destroyed tens of thousands of
cars throughout the Lower Keys. Key West looked like a ‘car graveyard’ and we saw tractor
trailer loads of cars coming and going on the Overseas Highway for months after Wilma. The
storm destroyed the piers at the clothing optional Atlantic Shores motel and breached the shark
tank at the Key West Aquarium, freeing its sharks. Damage postponed Key West’s Halloween
Fantasy Fest until the following December.
In March 2006, the NOAA opened its National Weather Forecasting Building on White Street.
This building is designed to withstand a Cat 5 hurricane and its storm surge.
The previous most intense hurricane was Hurricane George, a category 2 storm in September of
Tropical Cyclone Basics
Tropical cyclones are warm core, non-frontal low pressure systems of synoptic scale that
develop over tropical or subtropical waters and have a definite organized surface circulation.
Tropical depressions, tropical storms, and hurricanes are all forms of tropical cyclones,
differentiated only by the intensity of the winds associated with them.
Tropical Wave (African or Easterly Wave)
A tropical wave is a trough or cyclonic curvature maximum in the trade wind easterlies. These
waves tend to reach maximum amplitude in the lower to middle troposphere and may or may
not be accompanied by thunderstorm clusters. Although there is still some debate on the issue,
these easterly waves are thought to originate or become amplified as a result of meteorological
conditions over the continent of Africa. Each hurricane season approximately 60 of these waves
cross the tropical North Atlantic. Although the majority of these waves pass through the basin
without any significant tropical cyclone development, passage of these waves is often
accompanied by squally weather with brief periods of higher sustained winds.
A tropical disturbance is a discrete tropical weather system with apparently organized
convection (generally 100 to 300 miles in diameter) originating in the tropics or subtropics,
having a nonfrontal migratory character, and maintaining its identity for 24 hours or more.
Tropical cyclones in which the maximum sustained surface wind speed (1-minute mean) is 38
mph (33 KT) or Iess. Tropical depressions must have a closed surface circulation in order to be
classified in this category.
Tropical cyclones in which the maximum sustained surface wind speed (1-minute mean)
ranges from 39-73 mph (34 KT to 63 1
Tropical cyclones in which the maximum sustained surface wind speed (1-minute mean) is
greater than or equal to 74mph (64 KT).
Hurricane Categories (Saffir-Simpson Hurricane Scale)
Hurricanes are further categorized according to the strength of their winds using the Saffir-
Simpson Hurricane Scale (SSHS).
A Category 1 storm has the lowest wind speeds, while a Category 5 has the highest. These are
relative terms because lower category storms can sometimes inflict greater damage than
higher category storms, depending on angle of approach, location, and many other aspects
particular to each system. Even tropical storms can produce significant damage & loss of life,
mainly due to floods.
Category 1 Hurricane — winds 74-95 mph (64-82 kt)
No real damage to buildings. Damage to unanchored mobile homes. Some damage to poorly
Also, some coastal flooding and minor pier damage. Examples: Irene 1999 and Allison 1995
Category 2 Hurricane — winds 96-110mph (83-95 kt) Some damage to building roofs,
doors and windows. Considerable damage to mobile homes. Flooding damages piers and
small craft in unprotected moorings may break their moorings. Some trees blown down.
Examples: Georges 1998 and Gloria 1985
Category 3 Hurricane — winds 111-130mph (96-113 kt) Some structural damage to
small residences and utility buildings. Large trees blown down. Mobile homes and poorly built
signs destroyed. Flooding near the coast destroys smaller structures with larger structures
damaged by floating debris. Terrain may be flooded well inland. Examples: Keith 2000,Fran
1996 Opal 1995,Alicia 1983 and Betsy 1965
Category 4 Hurricane — winds 131-155 mph (114-135 kt) More extensive curtainwall
failures with some complete roof structure failure on small residences. Major erosion of beach
areas. Terrain may be flooded well inland. Examples: Hugo 1989 and Donna 7960
Category 5 Hurricane — winds 156mph and up (135+ kt) Complete roof failure on many
residences and industrial buildings. Some complete building failures with small utility
buildings blown over or away. Flooding causes major damage to lower floors of all structures
near the shoreline. Massive evacuation of residential areas may be required. Examples:
Andrew 1992, Camille 7969 and Labor Day 1935
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