Hurricanes and Typhoons

HURRICANES AND TYPHOONS are tropical cyclones with maximum sustained winds of at least 74 mi. per hour (64 knots). Tropical cyclones that originate over the tropical Atlantic basin or the eastern/central North Pacific basin are called hurricanes, while those that originate in the tropical western North Pacific are called typhoons. Before the tropical cyclone reaches hurricane or typhoon status, there are stages of development the system will go through from birth to decay. Initially, when a poorly-organized mass of thunderstorms produces a weak circulation, the system is known as a tropical disturbance or tropical wave. When the winds increase to between 20 and 34 knots, the system is upgraded to a tropical depression, and when the winds increase to between 35 and [Page 514]64 knots, ...