Most disasters come with no warning. However, incidents such as hurricanes and tornadoes, which have devastating effects, do come with some type of advanced notice. Monitor weather reports by listening to the local television or radio networks or by purchasing a weather radio. These resources typically get their information from the National Weather Service and do a good job of quickly distributing it. Check out the Storm Notices page for more information.
Hurricanes are types of tropical cyclones that form in the warm waters of the Atlantic Ocean. They are tightly coiled bundles of wind turning counter-clockwise in the Northern hemisphere. Once these storms form their specific circulation patterns, they are defined by their wind speed.
Tropical depressions have maximum sustained winds of 38 miles per hour or less. Tropical storms have maximum sustained winds of 39 to 73 miles per hour. Hurricanes have sustained winds of more than 74 miles per hour.
Tornadoes, however, develop during violent thunderstorms. They don't have the life expectancy (counted in minutes instead of days) of hurricanes and therefore much less warning is available. Weather experts look for conditions that are conducive to tornado formation or sightings of tornadoes to warn the public. Tornadoes usually develop along storm fronts. Before thunderstorms develop, there is a change in wind direction and speed. This creates a horizontal spin low in the atmosphere. The air rises in a thunderstorm which tilts this horizontal spinning air. This area of rotation extends through most of the storm. The tornadoes develop within this area.
Most tornadoes are weak (winds less than 110 miles per hour) and last only a few minutes. These are still very dangerous and can cause damage. Some tornadoes may last 20 minutes or longer and have winds of up to 110 to 205 miles per hour. The worst tornadoes last up to 1 hour and have winds greater than 205 miles per hour. These cause the most damage and the greatest loss of life, but account for very few tornadoes.