It is the most violent hurricane that the Bahamas has experienced until today. Dorian, which hit the east coast of the United States on Sunday, reached winds of 295 km / h, a power strong enough to classify it in category 5, or even category 6, as Jean-Marie Noël Degrâce, forecaster at Météo-France. But what exactly do these units of measurement correspond to?

Hurricane Dorian, which struck northern Bahamas, is one of the worst storms in the history of this Caribbean archipelago. It is also the fifth category 5 hurricane to have formed in the Atlantic in the last four years. What is a category 5 hurricane?

In meteorology, scientists classify hurricanes on a scale of 1 to 5 on the so-called Saffir-Simpson scale, to describe the intensity of storms. Category 5 hurricanes generate winds greater than 252 kilometers per hour, according to this classification. In addition to the devastating winds, this type of hurricane can be accompanied by torrential rains and catastrophic rising waters, causing tsunami-like floods when they hit the coast.

Winds of 290 km / h and gusts to 325 km / h

Yet, as Jean-Noël Degrace, weather forecaster Météo-France explains, category 5 is no longer as adapted to new natural disasters as before: "We are at the top of category 5. We almost want to be in a category 6 but it does not exist, "says the meteorologist, describing" average winds of the order of 290 km / h and gusts that are 325 km / h ".

Hurricane Dorian's winds hit nearly 300 km / h, an unparalleled level in the history of the Bahamas, according to the National Hurricane Center (NHC). This type of cyclone is also becoming more frequent: one has been observed each year since 2015, a record series. They were much rarer before.

"What is happening is completely in line with what we have been saying for years about climate change," says Jean-Noël Degrâce. There should be regular more and more major hurricanes that could even be beyond what we have known. "

Small and big storms

In 2016, Hurricane Matthew was the first Category 5 hurricane to hit the Atlantic since 2007. Another category 5 hurricane, Irma, devastated the Caribbean and southern United States in September 2017. Particularly violent, the Hurricane Katrina, also Category 5, killed more than 1,800 people on the Gulf Coast in 2005.

In comparison, Hurricane Florence in 2018 was downgraded to category 1, before touching the coasts of North Carolina and South Carolina, though it was extremely dangerous. "An event of lesser category can be dangerous and do great damage," said Emmanuel Bocrie, weather forecaster at Météo-France, interviewed at the time.

Less powerful, however, Florence had poured torrential rains into lands already waterlogged in North Carolina, South Carolina and western Virginia, causing floods and leaving more than 480,000 homes without electricity.