Topline
Hurricane Milton—the Atlantic storm forecast to be “one of the most destructive hurricanes on record for west-central Florida”— has fluctuated between the two most intense hurricane classifications in the runup to its anticipated landfall and sparked debate about introducing a Category 6 distinction as climate change intensifies extreme weather events.
An aerial view of damaged houses are seen after Hurricane Helene made landfall in Horseshoe Beach, … [+]
Key Facts
Milton, which is expected to make landfall Wednesday evening, was downgraded to a Category 4 hurricane Tuesday morning.
The hurricane notched sustained wind speeds of 180 mph Monday, classifying it for a time as a Category 5 storm—the highest distinction possible.
Descriptions of the storm’s rapid intensification and destructive potential have reignited debate on social media about whether to introduce a sixth category to the Saffir-Simpson Hurricane Wind Scale used by the National Hurricane Center, which ranks storms up to a Category 5 based on their sustained wind speed (Cat 5 storms have wind at or greater than 157 mph).
Earlier this year, a pair of researchers with the Lawrence Berkeley National Laboratory and Space Science and Engineering Center argued that the intensifying impacts of climate change could soon force the addition of a sixth hurricane category to describe storms with wind speeds above 192 mph.
Scientists Michael Wehner and James Kossin argued that the open-endedness of the current wind scale has become “increasingly problematic for conveying wind risk in a warming world” and warned that intense storms are likely to become more common as climate change worsens.
Get Forbes Breaking News Text Alerts: We’re launching text message alerts so you’ll always know the biggest stories shaping the day’s headlines. Text “Alerts” to (201) 335-0739 or sign up here.
Surprising Fact
Even if Category 6 storms did exist, Milton would not have been one of them. The storm’s top maximum sustained wind speed was 180 degrees as of Monday evening, 12 mph lesser than the 192 needed to upgrade the storm under the researchers’ proposal.
Big Number
5. That’s how many storms could have been classified as a Category 6 between 1980 and 2021, meaning they exceeded maximum sustained winds of 192 mph. Of those, only one threatened North America. Hurricane Patricia made landfall in Mexico as a Category 4 hurricane in 2015 and became the strongest storm ever recorded in the western hemisphere with 215 mph winds. The other four storms all occurred in the Western Pacific.
Key Background
Climate change has not led to a marked difference in the number of hurricanes hitting the United States every year, but it has been blamed for intensifying those that do form. Higher temperatures allow for more intense evaporation, which allows storms traveling across warm oceans to pull in more water vapor and heat, leading to more rainfall and stronger winds. Additionally, sea level rise intensifies storm surge, pushing more water further inland during hurricanes. Even so, Category 5 hurricanes are somewhat rare. Only 42 tropical cyclones have reached Category 5 status since 1924, CBS News reported. Of those, 18 of those have formed since 2003.
Tangent
Hurricane Milton is moving over Mexico’s Yucatan Peninsula Tuesday, before crossing the eastern Gulf of Mexico. It is forecast to hit the west coast of Florida by Wednesday evening. Milton is expected to continue fluctuating in strength for the next day or so while it moves across the Gulf of Mexico and will likely weaken slightly before it hits Florida, but the National Hurricane Center warns “there is high confidence that Milton will remain an extremely dangerous hurricane when it reaches the state.” Milton is set to hit Florida just two weeks after Hurricane Helene did so before moving on to cause catastrophic flooding across parts of the southeastern U.S. The impacts of Helene moved further inland than expected, devastating western North Carolina and parts of Eastern Tennessee. More than 220 people died from the impacts of Helene, and hundreds more are still missing.