Hurricane Questions and Answers

THE ATLANTIC HURRICANE season in year 2008 will be much more active than average.

Fifteen named storms are predicted for the Atlantic Basin between June 1 and October 30, 2008. From those storms, eight hurricanes are predicted, four of which will be classified as "intense," or major hurricanes with sustained winds of 111 mph or greater.

Hurricane forecasts do not predict whether a storm will actually reach land (called landfall). These include only the Atlantic Basin -- the area encompassing the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico.

Track the forecasts as they are updated by Colorado State University and Dr. Gray and see up-to-the-moment weather maps at N.O.A.A.

What are the chances of a hurricane actually hitting the East Coast?

Though individual hurricane landfall can not be accurately forecast for an individual year, for those living on the East Coast, including the Florida Peninsula, there is a 45 percent probability of having a Category 3, 4, or 5 hurricane (on the Saffir-Simpson Hurricane Scale; more about this later) actually reach land. This might not seem much, but it is greater than the landfall probability from last century, which was 31 percent. For the residents of the Gulf Coast from the Florida Panhandle westward to Brownsville, the probability of landfall is slightly less -- 44 percent, compared to 30 percent last century.

What will the 2008 hurricanes be called?

The names chosen for the tropical storms of the 2008 Atlantic season are Arthur, Bertha, Cristobal, Dolly, Edouard, Fay, Gustav, Hanna, Ike, Josephine, Kyle, Laura, Marco, Nana, Omar, Paloma, Rene, Sally, Teddy, Vicky, Wilfred.

Most names are taken from a permanent list that rotates every six years. More than sixty names have been retired since 1950 because they resulted in significant property damage or deaths, including Camille (1969), Agnes (1972), Carmen (1974), Hugo (1989), Andrew (1992), Mitch (1998), Floyd (1999), Lili (2002), Dennis (2005), Katrina (2005), Rita (2005), Stan (2005), and Wilma (2005). A name can be retired at the request of a country affected by the storm if it is approved by the Hurricane Committee. It should be noted that not all hurricanes were named, including some of the most deadly or damaging storms known to man.

How many hurricanes can we expect during any given hurricane season in the Altlantc Ocean?

Each year an average of ten tropical storms develop in the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. Six of them, on average, will actually achieve hurricane status. Many of these storms will die out over the ocean. Over the course of three years, about five hurricanes will strike the U.S. coastline. Of these five, two will be major hurricanes of Category 3 or greater.

Just what is a hurricane?

A hurricane is a tropical storm with winds that have reached a constant speed of at least 74 mph in the North Atlantic Ocean, Caribbean Sea, or Gulf of Mexico. A hurricane's winds blow in a large spiral around a relatively calm center of extremely low pressure known as the eye of the storm. Around the rim of the eye, winds may gust to more than 200 mph. The eye of a storm is usually 20 to 30 miles wide and may extend over 400 miles. The entire storm can be up to 340 miles in diameter, dominating the ocean surface and lower atmosphere for thousands of square miles.

The dangers of a storm include torrential rains, high winds, and storm surges. A hurricane can last for two weeks or more over open water and can follow a path across the entire length of the eastern seaboard, coastal areas, and barrier islands. All Atlantic and Gulf coastal areas are subject to hurricanes or tropical storms. Although rarely struck by hurricanes, parts of the Southwest and Pacific Coast suffer heavy rains and floods each year from the remnants of hurricanes spawned off Mexico. Islands such as Hawaii, Guam, American Samoa, and Puerto Rico also are subject to hurricanes.

Is a hurricane the same as a cyclone?

A hurricane is actually one of three kinds of tropical storms, or cyclones, that circulate over tropical waters. The circulation is counterclockwise in the Northern Hemisphere. Tropical cyclones are classified as follows:

Tropical depression. An organized system of clouds and thunderstorms with a defined circulation and maximum sustained winds of 38 mph (33 knots) or less.

Tropical storm. An organized system of strong thunderstorms with a defined circulation and maximum sustained winds of 39 to 73 mph (34 to 63 knots).

Hurricane. An intense tropical weather system with a well-defined circulation and maximum sustained winds of 74 mph (64 knots) or higher. In the western Pacific, hurricanes are called typhoons. Similar storms in the Indian Ocean are called cyclones.

Hurricanes are further classified by rank according to how strong their winds are.

How are hurricanes classified?

The Saffir-Simpson Hurricane Scale is a 1-5 rating based on the hurricane's present intensity. This is used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall. Wind speed is the determining factor in the scale, as storm surge values are highly dependent on the slope of the continental shelf in the landfall region. Wind speeds are measured using a 1-minute average.

What do the hurricane warnings mean?

A watch means that hurricane-force winds are possible within 36 hours. A warning means that hurricane-force winds are likely within 24 hours.

How is a hurricane formed?

A tropical ocean and its atmosphere create the right conditions for a hurricane. Hurricanes draw their energy from the warm surface waters of the tropics (usually above 27 degrees Celsius, or about 81 degrees Fahrenheit) and the latent heat of condensation. Powered by heat from the sea, they are steered by the easterly trade winds and the temperate westerlies, as well as by their own ferocious energy. Around their core, winds grow with great velocity, generating violent seas. Moving ashore, they sweep the ocean inward while spawning tornadoes and producing torrential rain and floods. When hurricanes move over cold water or over large landmasses, they can die out quickly because they lose the power of the heat and condensation.

What were the worst hurricanes to hit the United States?

The top six hurricanes, in terms of damage cost estimates, to hit the U.S. Atlantic region are as follows:

The six deadliest hurricanes in the Atlantic region 1900-2005: