Photo courtesy U.S. Army Corps of Engineers Many communities and small towns in eastern North Carolina found themselves afloat following Hurricane Floyd's massive rainfall and the ensuing floods. Streams and waterways were already swollen from Hurricane Dennis, which struck eastern North Carolina (twice) just weeks before Hurricane Floyd.

It can take anywhere from hours to several days for a thunderstorm to develop into a hurricane. Although the whole process is not entirely understood, three events must happen for hurricanes to form. A continuing evaporation-condensation cycle of warm, humid ocean air takes place. Patterns of wind, characterized by converging winds at the surface and strong, uniform-speed winds at higher altitudes, develop. A difference in air pressure between the surface and high altitude happens.

Photo courtesy NASA This photo is a composite of three days' views (August 23, 24 and 25, 1992) of Hurricane Andrew as it slowly moved across south Florida from east to west.

Hurricanes in the Northern Hemisphere rotate counterclockwise (west to east) and move through the ocean clockwise (east to west). In the Southern Hemisphere, hurricanes rotate clockwise (east to west) and move counterclockwise (west to east). These motions, known as the Coriolis effect, are caused by the Earth's rotation. To monitor and track the development and movement of a hurricane, we rely on remote sensing by satellites and data gathered by the Hurricane Hunters and researchers at The National Oceanic and Atmospheric Administration (NOAA).

Weather satellites use different sensors to gather different types of information about hurricanes, such as clouds, circulation patters, wind speeds, amounts of rainfall, temperature differences and even cloud heights.

All this information is relayed back to the National Hurricane Center in Miami, FL. Here it is interpreted and distributed to national and local news media. The National Hurricane Center predicts the hurricane's movement and intensity using various weather models and issues hurricane watches and warnings to areas in the storm's path. A tropical-storm watch is issued when sustained winds from 39 to 73 mph are possible in your area within 36 hours. A tropical-storm warning indicates that these conditions are likely in your area within 24 hours. A hurricane watch is issued when hurricane conditions (sustained winds greater than 74 mph) are possible in your area within 36 hours. A hurricane warning is issued when these conditions are likely in your area within 24 hours.

Our modern system (tracking, early detection, warnings) has greatly reduced the loss of life during a hurricane.

Photo courtesy NASA/GSFC Hurricane Floyd was a Category 3 storm that brought intense rains and record flooding to the eastern United States and Canada. Nearly 90 percent of the fatalities associated with this storm were drownings due to inland flooding.

How Hurricanes Form

Warm, moist air from the ocean surface begins to rise rapidly. As this warm air rises, its water vapor condenses to form storm clouds and droplets of rain. The condensation releases latent heat. This latent heat warms the cool air aloft, causing it to rise. This rising air is replaced by more warm, humid air from the ocean below. This cycle continues, drawing more warm, moist air into the developing storm and continuously moving heat from the surface to the atmosphere. This exchange of heat creates a pattern of wind that circulates around a center. This circulation is similar to that of water going down a drain.

Converging winds -- winds moving in different directions that run into each other -- at the surface collide and push warm, moist air upward. This rising air reinforces the air that is already rising from the surface, so the circulation and wind speeds of the storm increase. In the meantime, strong winds blowing at uniform speeds at higher altitudes (up to 30,000 ft.) help to remove the rising hot air from the storm's center, maintaining a continual movement of warm air from the surface and keeping the storm organized. If the high-altitude winds do not blow at the same speed at all levels -- if wind shears are present -- the storm loses organization and weakens.

High-pressure air in the upper atmosphere (above 30,000 ft) over the storm's center also removes heat from the rising air, further driving the air cycle and the hurricane's growth. As high-pressure air is sucked into the low-pressure center of the storm, wind speeds increase.

Hurricane Hunters

Photo courtesy U.S. Air Force / Hurricane Hunters The eye of a hurricane, as seen from the window of a hurricane-surveillance plane.

The Hurricane Hunters are members of the 53rd Weather Reconnaissance Squadron/403rd Wing, based at Keesler Air Force Base in Biloxi, Mississippi. Since 1944, they have been the only organization within the U.S. Department of Defense (which oversees the U.S. military) to fly into tropical storms and hurricanes. Since 1965, the Hurricane Hunters team has used the C-130 Hercules, a very sturdy turboprop plane. The team can cover up to five storm missions per day, anywhere from the mid-Atlantic to Hawaii.

NOAA also deploys planes for hurricane research. In fact, their planes are pretty famous, and it's not just because their noses are graced with some widely recognized cartoon characters. NOAA's two turboprop WP-3D Orions -- "Kermit the Frog" and "Miss Piggy" -- are considered among the world's best research aircraft. According to the NOAA Web site, Kermit and Miss Piggy "are on standby or deployed for hurricane research and reconnaissance 120 days each year ... flying 300 to 400 hours every year."

The Hurricane Hunters and NOAA aircraft are equipped with an impressive bank of high-tech instrumentation, radars and recording systems. All of which is crucial in studying hurricanes and conducting other weather research.