Hurricane terms

These are terms that National Hurricane Center officials and weather forecasters will use during hurricane season:

• TROPICAL DISTURBANCE: This is the initial stage of what could become a hurricane. It could form in the Atlantic Ocean or the Gulf of Mexico. It's a moving area of thunderstorms in the tropics that has an identity for 24 hours or longer.

• TROPICAL DEPRESSION: The next step up in a tropical system's formation. It's an organized system in which the clouds and thunderstorms have a defined circulation. It has maximum sustained winds of 38 mph or lower.

• TROPICAL STORM: This is an organized system of strong thunderstorms and has a defined circulation to it. Its maximum sustained winds range between 39 and 73 mph.

• HURRICANE: As a weather system intensifies and shows a well-defined circulation, it becomes a hurricane. In the Atlantic and Gulf, these are called hurricanes once maximum sustained winds reach 74 mph or higher. These are called typhoons in the Pacific and cyclones in the Indian Ocean.

• TROPICAL STORM WATCH: This is announced by the National Hurricane Center for coastal regions when tropical storm conditions may create a threat within 36 hours.

• TROPICAL STORM WARNING: This warning from the National Hurricane Center tells coastal residents they can expect tropical storm-force conditions in the defined area within 24 hours.

• HURRICANE WATCH: The National Hurricane Center will issue a hurricane watch when there is a threat of hurricane conditions within 30 to 36 hours. It's a signal for people in the affected area to make preliminary preparations and evacuation plans as warranted.

• HURRICANE WARNING: When this is issued by the National Hurricane Center, people in the affected area should immediately finish preparations to protect life and property. It means sustained winds of 74 mph or more are expected in a specified area in 24 hours or less. A hurricane warning can remain in effect when dangerously high water or high waves continue, even though winds may be less than 74 mph. A warning area could be far from the eye of the storm, depending on the distance hurricane-force winds extend out from the eye.

• STORM SURGE: This is an abnormal increase in the Atlantic or Gulf water above tidal levels and can extend out 50 to 100 miles from the storm. As a hurricane sweeps onto land, it pushes the water with it to create storm surge. This can be the most devastating part of a storm along the coast, creating damage first as the water rushes ashore and then again as it washes back out to sea. It can push water up rivers and bays to inland areas.

Sources: National Hurricane Center and emergency management offices