Learn About Hurricanes
What is a Hurricane?
A hurricane is a type of tropical cyclone, the generic term for a low pressure system that generally forms in the tropics. A typical cyclone is accompanied by thunderstorms, and in the Northern Hemisphere, a counterclockwise circulation of winds near the earth’s surface.
All Atlantic and Gulf of Mexico coastal areas are subject to hurricanes or tropical storms. Parts of the Southwest United States and the Pacific Coast experience heavy rains and floods each year from hurricanes spawned off Mexico. The Atlantic hurricane season lasts from June to November, with the peak season from mid-August to late October.
Hurricanes can cause catastrophic damage to coastlines and several hundred miles inland. Winds can exceed 155 miles per hour. Hurricanes and tropical storms can also spawn tornadoes and microbursts, create storm surges along the coast, and cause extensive damage from heavy rainfall.
Hurricanes are classified into five categories based on their wind speed, central pressure, and damage potential (see chart). Category Three and higher hurricanes are considered major hurricanes, though Categories One and Two are still extremely dangerous and warrant your full attention.
How are the Hurricane Categories Determined?
| Saffir-Simpson Hurricane Scale | |||
|---|---|---|---|
| Scale Number (Category) |
Sustained Winds (MPH) |
Damage | Storm Surge |
| 1 | 74-95 | Minimal: Unanchored mobile homes, vegetation and signs. |
4-5 feet |
| 2 | 96-110 | Moderate: All mobile homes, roofs, small crafts, flooding. |
6-8 feet |
| 3 | 111-130 | Extensive: Small buildings, low-lying roads cut off. |
9-12 feet |
| 4 | 131-155 | Extreme: Roofs destroyed, trees down, roads cut off, mobile homes destroyed. Beach homes flooded. |
13-18 feet |
| 5 | More than 155 | Catastrophic: Most buildings destroyed. Vegetation destroyed. Major roads cut off. Homes flooded. |
Greater than 18 feet |
Hurricanes can produce widespread torrential rains. Floods are the deadly and destructive result. Slow moving storms and tropical storms moving into mountainous regions tend to produce especially heavy rain. Excessive rain can trigger landslides or mud slides, especially in mountainous regions. Flash flooding can occur due to intense rainfall. Flooding on rivers and streams may persist for several days or more after the storm.
Between 1970 and 1999, more people lost their lives from freshwater inland flooding associated with land falling tropical cyclones than from any other weather hazard related to tropical cyclones.
How are Hurricanes Named?
Since 1953, Atlantic tropical storms have been named from lists originated by the National Hurricane Center and now maintained and updated by an international committee of the World Meteorological Organization. The lists featured only women’s names until 1979. After that, men’s and women’s names were alternated. Six lists are used in rotation. Thus, the 2001 lists will be used again in 2007.
The only time there is a change in the list is if a storm is so deadly or costly that the continued use of the name would be inappropriate for reasons of sensitivity. When this occurs, the name is stricken from the list and another name is selected to replace it.
Sometimes names are changed. Lorenzo replaced Luis and Michelle replaced Marilyn. See the complete list of hurricane names.
Last Modified: Friday, 09-Jun-2006 15:22:25 EDT