| Hurricane Hazards, Warnings, Advisories, Categories and Evacuation Zones |
|
Hurricane Hazards |
Hurricanes can combine storm surge, powerful winds, tornadoes and torrential rains into a devastating combination.
Storm Surge Storm surge is an abnormal rise in sea level 50 to 100 miles wide that sweeps across the coast near where the "eye" of the hurricane makes landfall. The surge of high water, topped by waves, is devastating. Along the immediate coast, storm surge is the greatest threat to life and property. Most hurricane-related deaths are caused by drowning.
Winds Hurricane force winds, 74 mph or more, can destroy buildings and mobile homes. Debris can become flying missiles in hurricanes. Winds often stay above hurricane strength well inland. If you do not have to evacuate, it is extremely important to secure your home and cover your windows before the storm. Remember, mobile homes are extremely vulnerable to high winds and should be evacuated.
Heavy Rains and Floods Widespread torrential rains often in excess of 10 inches can accompany a hurricane and can produce destructive floods. This is a major threat to areas well inland.
Tornadoes Hurricanes also produce tornadoes, which add to the hurricane's destructive power.
|
Hurricane Warnings and Advisories |
Tropical Depression A disturbance with a clearly defined low pressure area; high wind speed is 38 mph.
Tropical Storm A distinct low pressure area defined by a counterclockwise rotating circulation with winds of 39 - 73 mph.
Hurricane Once a tropical storm's constant wind and speed reaches 74 mph or greater, it is classified as a hurricane. In the western Pacific hurricanes are called typhoons. Similar storms in the Indian Ocean are called cyclones.
Tropical Storm Watch An alert for a specific area that a tropical storm may pose a threat within 36 hours.
Tropical Storm Warning An alert that tropical storm conditions, including sustained winds of 39 to 73 mph are expected in specific areas within 24 hours.
Hurricane Watch An alert for specific areas that hurricane conditions pose a threat to an area within 36 hours.
Hurricane Warning An issued when hurricane conditions (winds of 74 miles per hour or greater, or dangerously high water and rough seas) are expected in 24 hours or less. All precautions should be completed immediately.
Evacuation Order The most important instruction you will receive. Once issued, an evacuation order is mandatory.
|
Hurricane Categories and Evacuation Zones |
Category 1 Hurricane - 74 - 95 mph
No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal road flooding and minor pier damage.
Category 2 Hurricane - 96 – 110 mph
Some roofing material, door, and window damage to buildings. Considerable damage to vegetation, mobile homes, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of center. Small craft in unprotected anchorages break moorings.
Category 3 Hurricane - 111 – 130 mph
Some structural damage to small residences and utility buildings with a minor amount of curtainwall failures. Mobile homes are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris. Terrain continuously lower than 5 feet ASL may be flooded inland 8 miles or more.
Category 4 Hurricane - 131 – 155 mph
More extensive curtainwall failures with some complete roof structure failure on small residences. Major erosion of beach. Major damage to lower floors of structures near the shore. Terrain continuously lower than 10 feet ASL may be flooded requiring massive evacuation of residential areas inland as far as 6 miles.
Category 5 Hurricane - Above 155 mph
Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Major damage to lower floors of all structures located less than 15 feet ASL and within 500 yards of the shoreline.Massive evacuation of residential areas on low ground within 5 to 10 miles of the shoreline may be required.
|
