What is a Tropical Cyclone?
Tropical cyclones are among nature's most powerful and destructive phenomena. If you live in an area prone to tropical cyclones, you need to be prepared. Even areas well away from the coastline can be threatened by destructive winds, tornadoes and flooding from these storms. How great is the danger? For 1970-2010, the average numbers per year were as follows:
* Atlantic Ocean, Caribbean or Gulf of Mexico: 11 tropical storms, 6 of which became hurricanes
* East Pacific Ocean: 15 tropical storms, 8 of which became hurricanes
* Central Pacific Ocean: 4 tropical storms, 2 of which became hurricanes
Over a typical 2-year period, the U.S. coastline is struck by an average of 3 hurricanes, 1 of which is classified as a major hurricane.
While hurricanes pose the greatest threat to life and property, tropical storms and depressions also can be devastating. Floods from heavy rains and severe weather, such as tornadoes, can cause extensive damage and loss of life. For example, Tropical Storm Allison produced over 40 inches of rain in the Houston area in 2001, causing about $5 billion in damage and taking the lives of 41 people.
Tropical cyclones forming between 5 and 30 degrees North latitude typically move toward the west. Sometimes the winds in the middle and upper levels of the atmosphere change and steer the cyclone toward the north and northwest. When tropical cyclones reach latitudes near 30 degrees North, they often move northeast. Hurricane seasons and their peaks are as follows:
* Atlantic and Caribbean: Jun. 1 to Nov. 30 with peak mid-August to late October.
* Central Pacific (Hawaii): Jun. 1 to Nov. 30 with peak from July to September.
* East Pacific: May 15 to November 30
* Western North Pacific: Tropical cyclones can strike year round