Tropical cyclones are rotating low pressure weather systems with thunderstorms but no fronts. When these cyclones reach 74 mph or higher, they become hurricanes. Once the storm becomes categorized a hurricane, they get rated between 1 to 5, depending on the maximum sustained winds. The higher the category, the greater the hurricane's potential for property damage. A six year rotating list of names, update and maintained by the World Meteorological Organization, is used to identify these storms. "Hurricane Season" begins on June 1st and ends on November 30th, although hurricanes have occurred outside the time frame. NOAA's (National Oceanic and Atmospheric Administration) National Hurricane Center predicts and tracks these massive storm systems, which occur, on average, 12 times a year in the Atlantic Basin.