Tropical Cyclones

What is a Tropical Storm or Hurricane?

Is a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation. Additional information can be found at the Tropical Cyclone Climatology page.

How does a Tropical Storm/Hurricane get its name?

The National Hurricane Center will give a name to a tropical cyclone that meets Tropical Storm strength or higher. This name will remain with the system if the tropical cyclone is upgraded (example, Tropical Storm Irma has been upgraded to Hurricane Irma). Storm names are retired based on significant events.

The list of current names can be found at the National Hurricane Center site.

Hurricane Evolution

Evolution of a hurricane is categorized by the Saffir-Simpson Scale.

  1. Tropical Depression: sustained winds of 38 mph or less.
  2. Tropical Storm: sustained winds of 39 to 73 mph.
  3. Hurricane: sustained winds of 74 mph or higher.
  4. Major Hurricane: sustained winds of 11 mph or higher, a major hurricane corresponds to a Category 3, 4, or 5 storm.
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