Hurricanes, Tropical Storms and Tropical Depressions  

    Hurricanes are one of the most deadly weather phenomenon's.  They form over open water in the tropics.  They can form very rapidly in water in the 70's and up (F). The most deadly aspect of a hurricane is the storm surge.  The storm surge is like a wall of water that comes ashore near where the eye or center of the storm makes landfall.  Any type of tropical system contains heavy rainfall to the extent of major flooding.  When Hurricane Danny made landfall in Mobile Bay, AL in 1997 close to 30" of rain fell causing extensive damage.  The aspect that people most commonly think of are the very high winds that tropical systems can have (See Chart lower left).  Once a hurricane has winds of at least 110 mph. it is considered a major hurricane.  The scale of damage produced by a hurricane is called the Saffir-Simson Scale.  A hurricane is rated on a scale from 1-5 (catagory).  The 3th column is the central barometric pressure in millibars. A hurricane can also produce tornadoes when it makes landfall.  See tornado section.
 

   
This satellite loop shows the movement of two hurricanes, Bonnie making landfall in North Carolina and Danielle moving to the north of the Leeward Islands.  This shows wonderfully the counterclockwise rotation associated with hurricanes and tropical storms.  Also note the outflow (clouds moving away from the system) 

When a tropical system develops and moves near land many different advisories made be issued.

SMALL CRAFT ADVISORY - A hurricane is within a few hundred miles of the coast.  Small craft operators should not go out into open ocean waters.

TROPICAL STORM WATCH - Tropical storm conditions (39-74 mph winds) may be seen in 36 hrs.

TROPICAL STORM WARNING - Tropical storm conditions (39-74 mph winds) are likely in 24 hrs.

HURRICANE WATCH - Hurricane conditions may be seen within 36 hrs.  This does not imply danger is imminent, it means be ready.

HURRICANE WARNING - Hurricane conditions are likely within 24 hrs.  This is serious, high water and high winds are expected.

TORNADO WARNING - Tornados have been sighted in the area.  Moved to the lowest inner-most room of the house.

Visit the Weather Channel web site or the National Hurricane Center's web site for information of current storms and their tracks.