Hurricanes are intense tropical weather disturbances with a well-defined circulation and sustained winds of 74 mph or higher. Hurricanes need warm ocean water (at least 80 degrees F) in order to thrive. They also need a moist environment and non-shearing winds in the upper atmosphere so that the hurricane can grow vertically.
Hurricanes typically move in a course around a Bermuda High, a large high-pressure system typical for the mid-Atlantic region. Some hurricanes move on erratic paths and can be difficult to forecast.
Hurricanes are named to keep track of different storms occurring at the same time. Official naming of tropical storms and hurricanes began in 1953. In 1979 male names were added to the list of names; which is comprised of six annual lists that are rotated every six years. If a tropical storm or hurricane causes notable death and destruction, the name is "retired" off of the list and replaced with another name.
Storm surge is an abnormal rise in sea level accompanying a hurricane or other intense storm, and whose height is the difference between the observed level of the sea surface and the level that would have occurred in the absence of the tropical disturbance. Storm surge is usually estimated by subtracting the normal or astronomic high tide from the observed storm tide. Because of improvements in forecasting, the spread of information and timely evacuations, the number of fatalities from hurricane storm surge has been drastically reduced over the past 30 years. However, the element of risk is always there. With the enormous increase in coastal populations, it is more critical than ever to understand the risks from hurricane storm surge; and more importantly, heed the warnings and evacuation orders given by local emergency management officials. The rise in water, coupled with the battering waves on top of the elevated water level is the reason that sometimes millions of people are urged to evacuate their coastal homes.