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Hurricanes have been strengthening – like Beryl. Some scientists propose a Category 6.

The 2024 U.S. hurricane season, now underway, is predicted to be among the worst in decades. Before the National Oceanic and Atmospheric Administration made that forecast, a debate had been swirling about whether new vocabulary is needed to reflect the growing intensity of storms.

Category 5, signifying sustained winds stronger than 156 mph, is the highest marker on the Saffir-Simpson hurricane scale. Many Americans know the categories from weather reports and use them to decide how to prepare for storms.

Why We Wrote This

Hurricane season in the United States has begun. Given the growing intensity of storms, a debate has been swirling about whether a new category is needed on the Saffir-Simpson scale.

But in the past decade, the sustained wind speeds of eight hurricanes impacting the United States have surpassed 156 mph, killing 133 people and causing roughly $77 billion in damage. In recent months, some scientists have asked whether it’s time to add a Category 6 to the scale.

The big question is whether such a change would help save lives. Suzana Camargo of Columbia University’s Lamont-Doherty Earth Observatory sees potential. “In terms of communicating risk and having people change their behavior, it might work,” she says.

The 2024 U.S. hurricane season, now underway, is predicted to be among the worst in decades. Before the National Oceanic and Atmospheric Administration made that forecast, a debate had been swirling about whether new vocabulary is needed to reflect the growing intensity of storms.

Category 5, signifying sustained winds stronger than 156 mph, is the highest marker on the Saffir-Simpson hurricane scale. Currently Hurricane Beryl is churning through the Caribbean and is the earliest Atlantic hurricane on record to reach Category 5 strength. The storm, recently downgraded to Category 4, is expected to pass on a path near Jamaica on Wednesday and then move on toward the Cayman Islands and Mexico on Thursday. 

Many Americans know the categories from weather reports and use them to decide how to prepare for storms. But in the past decade, the sustained wind speeds of eight hurricanes impacting the United States have surpassed 156 mph, killing 133 people and causing roughly $77 billion in damage. In recent months, some scientists have asked whether it’s time to add a Category 6 to the scale.

Why We Wrote This

Hurricane season in the United States has begun. Given the growing intensity of storms, a debate has been swirling about whether a new category is needed on the Saffir-Simpson scale.

How did the five-step scale come about?

In 1969, American civil engineer Herbert Saffir was conducting research for the United Nations on how to prevent hurricane damage in low-income, storm-prone areas and saw there was no standard system to quantify the likely damage from hurricanes with winds above 74 mph. Mr. Saffir soon collaborated with National Hurricane Center (NHC) director Robert Simpson to release the Hurricane Disaster-Potential Scale.

In a 1974 article for the Weatherwise journal, Mr. Saffir and Mr. Simpson remarked that their wind-focused scale “gives probable property damage and evacuation recommendations.” Category 1 storms, they wrote, bring “damage primarily to shrubbery, trees, foliage and unanchored mobile homes,” and Category 5 storms are marked by “shrubs and trees blown down” and “complete failure of roofs on many residences and industrial buildings.”

Neil Frank, Mr. Simpson’s successor at the NHC, made it an official NHC metric. It eventually was renamed the Saffir-Simpson Hurricane Wind Scale and is used today to categorize storms in the Atlantic basin and parts of the Pacific Ocean.

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