National Hurricane Center definitions

Tropical Depression: An organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 mph or less

Tropical Storm: An organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds of 39-73 mph

Hurricane: An intense tropical weather system of strong thunderstorms with a well-defined surface circulation and maximum sustained winds of 74 mph or higher

Categories: Hurricanes are categorized according to the strength of their winds. A Category 1 storm has the lowest wind speeds, while a Category 5 hurricane has the strongest. However, lower category storms can sometimes inflict greater damage than higher category storms, depending on where they strike and the particular hazards they bring. In fact, tropical storms can also produce significant damage and loss of life, mainly due to storm surge and flooding.

Saffir-Simpson Hurricane Scale definitions

Tropical Storm - Winds 39-73 mph

Category 1 Hurricane — winds 74-95 mph (64-82 kt)

Damaging winds are expected. Some damage to building structures could occur, primarily to unanchored mobile homes (mainly pre-1994 construction). Some damage is likely to poorly constructed signs. Loose outdoor items will become projectiles, causing additional damage. Persons struck by windborne debris risk injury and possible death. Numerous large branches of healthy trees will snap. Some trees will be uprooted, especially where the ground is saturated. Many areas will experience power outages with some downed power poles.

Category 2 Hurricane — winds 96-110 mph (83-95 kt)

Very strong winds will produce widespread damage. Some roofing material, door, and window damage of buildings will occur. Considerable damage to mobile homes (mainly pre-1994 construction) and poorly constructed signs is likely. A number of glass windows in high rise buildings will be dislodged and become airborne. Loose outdoor items will become projectiles, causing additional damage. Persons struck by windborne debris risk injury and possible death. Numerous large branches will break. Many trees will be uprooted or snapped. Extensive damage to power lines and poles will likely result in widespread power outages that could last a few to several days.

Category 3 Hurricane — winds 111-130 mph (96-113 kt)

Dangerous winds will cause extensive damage. Some structural damage to houses and buildings will occur with a minor amount of wall failures. Mobile homes (mainly pre-1994 construction) and poorly constructed signs are destroyed. Many windows in high rise buildings will be dislodged and become airborne. Persons struck by windborne debris risk injury and possible death. Many trees will be snapped or uprooted and block numerous roads. Near total power loss is expected with outages that could last from several days to weeks.

Category 4 Hurricane — winds 131-155 mph (114-135 kt)

Extremely dangerous winds causing devastating damage are expected. Some wall failures with some complete roof structure failures on houses will occur. All signs are blown down. Complete destruction of mobile homes (primarily pre-1994 construction). Extensive damage to doors and windows is likely. Numerous windows in high rise buildings will be dislodged and become airborne. Windborne debris will cause extensive damage and persons struck by the wind-blown debris will be injured or killed. Most trees will be snapped or uprooted. Fallen trees could cut off residential areas for days to weeks. Electricity will be unavailable for weeks after the hurricane passes.

Hurricane Charley which made landfall in southwest Florida in 2004 was a Category 4 hurricane.

Category 5 Hurricane — winds 156 mph and up (135+ kt)

Catastrophic damage is expected. Complete roof failure on many residences and industrial buildings will occur. Some complete building failures with small buildings blown over or away are likely. All signs blown down. Complete destruction of mobile homes (built in any year). Severe and extensive window and door damage will occur. Nearly all windows in high rise buildings will be dislodged and become airborne. Severe injury or death is likely for persons struck by wind-blown debris. Nearly all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months.

Hurricane Andrew, which made landfall in southeast Florida in 1992, was a Category 5 hurricane with sustained winds of 165 mph.

The first depression of the 2009 season formed on May 28 in the mid-Atlantic near cape Hatteras. A low that passed through the Gulf of Mexico west of Florida the week before prompted the hurricane center to send out notices.

The National Hurricane Center keeps the public informed throughout the season, June 1 to Nov. 30, and begins sending out notices long before a storm arrives. It’s important to keep up with local weather forecasts and media reports to have the most advance warning of an approaching storm.

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