[Read our tips for protecting your home if you have to evacuate.]
Tropical cyclones around the world are named according to a list maintained by the World Meteorological Organization. The names of the deadliest storms, like Typhoon Haiyan or Hurricane Katrina, are retired.
Grading a storm’s intensity
Hurricanes are categorized 1 to 5 according to the Saffir-Simpson scale, which is based on wind speed. According to the National Hurricane Center, storms in Category 3 or higher, which have wind speeds of at least 111 miles per hour, “are considered major hurricanes because of their potential for significant loss of life and damage.” (Florence was a Category 4 as of early Wednesday.)
Typhoons are monitored by the Japan Meteorological Agency, which classifies them as “typhoon,” “very strong typhoon” or “violent typhoon,” depending on sustained wind speeds. Storms with wind speeds of less than 74 miles per hour are labeled “tropical depressions,” “tropical storms” or “severe tropical storms.”
The Joint Typhoon Warning Center, a United States military command in Pearl Harbor, Hawaii, also issues storm advisories using the designations “tropical depression,” “tropical storm,” “typhoon” and “super typhoon.”
Typhoon Jebi, which killed 11 people in Japan, was this season’s third super typhoon, meaning a typhoon with sustained surface winds of at least 150 miles per hour. It is the equivalent of a Category 4 or 5 hurricane in the Atlantic. This week, Southeast Asia and southern China are bracing for Super Typhoon Mangkhut.
Cyclones in the Indian Ocean are classified according to two intensity scales depending on where they are, with names like “very intense tropical cyclone” and “super cyclonic storm.” Australia rates cyclones from categories 1 to 5.
So why the three different words? Storm terminology has been highly influenced by the histories and cultural interactions of different regions. “Hurricane” appeared in English in the 16th century as an adaptation of the Spanish “huracán.” “Typhoon” is variously described as coming from Arabic (“tafa”) or Chinese (“taifeng”), perhaps both. “Cyclone” was coined in the late 18th century by a British official in India, from the Greek for “moving in a circle.”
But a storm by any other name should still be taken seriously.