Is it time to rethink hurricane categories?

ROB SCHMITZ, HOST:

Within the span of two weeks, two hurricanes, Helene and Milton, rocked the Southeastern United States. Both storms were categorized as major hurricanes - that’s a Category 3 or higher. And those categories, they’re known as the Saffir-Simpson scale, likely saved many lives by warning of the potential dangers of the storm, but some say that scale falls short. Alec Luhn is a climate journalist who’s reported on this. He says the scale accounts for wind speed but misses one key danger.

ALEC LUHN: Hurricanes are bringing more water our way, and water is actually the real killer when it comes to hurricanes, not wind speed. So a growing number of meteorologists are calling for a different way of categorizing and quantifying the destructiveness of a hurricane as we get these bigger, wetter hurricanes dumping a lot of rainfall and causing a big storm surge, which is a mass of seawater that’s coming up onto the coast or in some cases, like Hurricane Milton, generating many tornadoes all around the hurricane, far from the eye of the storm.

SCHMITZ: That’s interesting. You know, you mentioned water as an additional threat other than wind. You know, is there a consensus about what scientists should include, like water, in an updated scale for hurricanes?

LUHN: So the great power of the Saffir-Simpson scale is it’s so simple and evocative. You hear Category 5 - 5 out of 5 - you know it’s going to be big. It sounds big...

SCHMITZ: Right.

LUHN: ...And bad, and that’s what’s great about it. You don’t need to know too much about hurricanes to really understand that. So how do we keep that simplicity and convey that to people so easily, but also maybe give them a better sense of the destructiveness? One idea is to categorize hurricanes the same way, Categories 1 through 5, but based on sea level pressure rather than wind speed because a hurricane forms in an area of low pressure. So the lower the pressure, the stronger the storm. And that has an advantage over wind speed because it would gather those other kinds of storms that are destructive despite having lower wind speeds, right? In other words, that scale could amp up the number of the hurricane that was slower but still packed a bigger punch and put it on the same level as a small, tight hurricane that has high wind speed. So that’s one idea is to base it on sea level pressure.

There’s also an idea about doing a category system based on rainfall, Categories 1 through 5 based on how likely it is that the rainfall will be that many more times deadlier than what you’re used to. So in other words, a Category 3 would be three times as much rainfall as you would expect to see in an area in a five-year period.

Basically, long story short, there’s many ideas how to do this. But so far, it’s been hard to switch because Americans, everyone knows that Saffir-Simpson scale. Everyone understands hurricane Category 1 through 5.

SCHMITZ: You know, this brings up a bigger question also about climate change. You know, we know that warmer oceans are making storms more intense, wetter. What’s the likelihood that you think we’ll see a different type of warning system as we experience more intense hurricanes, thanks to climate change?

LUHN: I don’t think it’s very likely we’re going to switch away from the Saffir-Simpson scale anytime soon. While meteorologists can all point out its shortcomings, it conveys to people danger even if they know nothing almost about hurricanes. What I think some people are saying is that we need to try and educate the public and get them to think beyond just the scale and think about impacts of hurricanes and think about local impacts of hurricanes - right? - because if you live in a low-lying area near the coast, storm surge could be very, very deadly for you, much more deadly than wind speed or rainfall. If you live in an area inland with - that maybe doesn’t see all that much rain usually or doesn’t have a great drainage system, then you may be at risk for extreme rainfall. What is the thing that a hurricane could bring to your community that could make it deadly?

SCHMITZ: That’s Alec Luhn. He’s a climate journalist, and you can read his reporting on the Saffir-Simpson scale in WIRED magazine. Alec, thank you.

LUHN: Thanks. My pleasure. Transcript provided by NPR, Copyright NPR.