Category 6

ROMAN MARS: This is 99% Invisible. I’m Roman Mars. On the campus of Florida International University in Miami, there’s a place ominously named the Extreme Events Institute. They do things like map the risk of storm surge for the whole Caribbean and study how the public perceives the threat from natural disasters. They’re also home to the International Hurricane Research Center.

ALANA CASANOVA-BURGESS: And right there, next to a parking lot in front of an open field, they have this huge bright blue airplane hanger.

ROMAN MARS: That’s producer Alana Casanova-Burgess.


ALANA CASANOVA-BURGESS: Written across the massive closed doors, in big baby blue letters, it says “WOW,” which stands for “Wall of Wind.”




ERIK SALNA: They let you in, huh?

ALANA CASANOVA-BURGESS: Erik Salna, a meteorologist who works here, takes me inside the closed hanger. He notices the recorder I’m holding and the mic I have shoved in his face.

ERIK SALNA: Your hands are full. I was going to let you have the unique experience of opening one of the doors.


ALANA CASANOVA-BURGESS: He passes me a metal box with a big button.

ERIK SALNA: So, you’re going to press that open.


ALANA CASANOVA-BURGESS: And I kind of get the sense he does this with a lot of visitors.


ERIK SALNA: Okay. Three, two, one…

ALANA CASANOVA-BURGESS: The doors slide open, and all that Florida sunshine streams into the hangar, illuminating a wall of a dozen giant, yellow fans stacked in two rows of six.

ERIK SALNA: Yeah, so there you go. What do you think?


ERIK SALNA: That’s what everyone says. Never fails.

ROMAN MARS: Each fan is six feet in diameter. They were originally made for ventilating mining shafts, but engineers here have figured out how to get them to make hurricane strength winds.

ALANA CASANOVA-BURGESS: And that’s why I am here–because this is a lab where researchers are figuring out how we can make our homes and infrastructure survive hurricanes better, especially at a time when more intense storms are going to be more frequent. What shapes should a roof be so it stands a better chance of not getting blown off? Is it possible to make stronger doors? What’s the best kind of screw to use?

ERIK SALNA: When they used to make rooftops, they would use a nail that was nice and smooth. So, when a wind comes, it gets pulled right out. Well, what we developed here was a nail that looks like a screw. Now, if you put it into that wood, it’s not going to get pulled out like that.

ALANA CASANOVA-BURGESS (FIELD TAPE): You’re yanking your finger, and it’s not moving.

ERIK SALNA: It’s not moving.

ALANA CASANOVA-BURGESS: Everyone I met for this story bragged about how South Florida, which braces for hurricanes every summer, has adopted some of the toughest building codes in the country. And they’re updated regularly, so new building methods get factored in. It’s now required that all roofs use these special nails, based on research done here at the Wall of Wind.

ROMAN MARS: When all 12 fans are going full blast, this lab can test different construction methods against winds as high as 157 miles per hour. Hurricanes that strong are incredibly rare. They’ve only made landfall in the U.S. four times. One of them happened right here.

ERIK SALNA: Everyone here in South Florida–if you were down here–it’s a memory that you’ll never forget.

ROMAN MARS: Hurricane Andrew made landfall in 1992 just south of downtown Miami. Andrew had sustained winds of 165 miles per hour, destroying at least 50,000 homes–ripping some of them right off of their foundations. It was the costliest disaster in U.S. history at the time.

ERIK SALNA: Changed everything, changed emergency management, changed research, changed the building codes… All of those things were accelerated after Hurricane Andrew.

ALANA CASANOVA-BURGESS: Meteorologists designated Hurricane Andrew a so-called “Category 5” storm. Even if you don’t know much about hurricanes, you know a Category 5 is major. It’s actually the highest classification according to the scale we use to measure these things. The Saffir-Simpson Hurricane Wind Scale.

ROMAN MARS: For 50 years, the Saffir-Simpson Scale has been used to talk about how to build more resilient communities. It’s been the language that we all rely on to understand what kind of risk a hurricane poses. During storm emergencies, we are primed to hear about categories.

ALANA CASANOVA-BURGESS: And the scale has transcended hurricanes. It’s been adopted as a common shorthand for describing damage of all kinds. We use it for situations that have absolutely nothing to do with weather.

MSNBC: Midterm madness? More like a Category 4 hurricane…

FOX: We’re now treating this like a massive, Cat 5 hurricane disaster. Homeland Security Secretary Nielsen there, sounding the alarm on the immigration crisis ahead of…

CNN: Donald Trump is a Cat 5 disaster for American political discourse…

ROMAN MARS: The reason the Saffir-Simpson Scale has been adapted so much is because it’s really good at what it does. It’s a clear, easy shorthand for damage. It tells us what we can expect from different categories of hurricane strength winds–what they’re likely to do to our homes, our infrastructure, and our communities. It’s a snapshot of probable impact.

ALANA CASANOVA-BURGESS: The thing is, five decades on, we’ve got different homes, different infrastructure, and different communities. Scientists say even our hurricanes are different these days. And there are doubts now about whether the Saffir-Simpson Scale is telling us enough in that snapshot and whether it still serves this changing world we live in.

ROMAN MARS: Because hurricanes are so chaotic, they’ve always been a bit tricky to characterize, even in an age of satellites and radar. They’re capricious. They can get stronger or weaker and change direction quickly. No two are the same, and even a single hurricane isn’t uniform all the way around. They have a stronger side and a weaker one.

ERIC JAY DOLIN: Hurricanes are facts of nature. The best that we can do is forecast them, monitor them, understand them, and react to them when they do approach–and then deal with the aftermath once they’ve left.

ALANA CASANOVA-BURGESS: Eric Jay Dolin is the author of A Furious Sky: The Five Hundred-Year History of America’s Hurricanes. For a lot of that history–

ERIC JAY DOLIN: Hurricanes were almost mystical events–the hand of God made manifest.

ALANA CASANOVA-BURGESS: Modern forecasting didn’t exist until the mid 19th century. Before that, the Taino–who were among the original inhabitants of the Caribbean–taught colonizers how to tell one was coming.

ROMAN MARS: There were small advances in understanding the basics of how they worked, but it wasn’t until the 1870s that observers began to accurately predict where that hurricane was coming from and going to and how destructive it might be when it got there.

ALANA CASANOVA-BURGESS: That big leap forward came from a Jesuit working out of a coastal observatory in Havana, Cuba. His name was Father Benito Viñes, but he was also known as the “Hurricane Priest.”

ERIC JAY DOLIN: The observatory had decades worth of observations, so he read through them, collected them, systematized them…

ALANA CASANOVA-BURGESS: And he had plenty of equipment, even some he invented himself.

ERIC JAY DOLIN: He would take up to ten measurements a day–different kinds of measurements: barometric measurements, precipitation, temperature…

ALANA CASANOVA-BURGESS: And he was really into watching clouds.

ERIC JAY DOLIN: Those were the wispy cirrostratus clouds. He called them “cat’s tails,” “cocks’ plumes,” “wind feathers”… And these clouds were followed by more denser clouds–cumulostratus and then cumulonimbus.

ALANA CASANOVA-BURGESS: These were all clues that he could use to predict where bad weather was coming from and headed to.

ERIC JAY DOLIN: So, he was able to develop a very intimate understanding of hurricanes and how they behaved, and he put together a fairly impressive record of predictions. It was more than just chance.

ROMAN MARS: Father Viñes set up a telegraph network for hurricane news from across the Caribbean. He made forecasts for the entire region that were printed in newspapers and eagerly read. It blew people’s minds that someone could forecast the path of these storms with such precision.

ALANA CASANOVA-BURGESS: The Hurricane Priest didn’t always get it right. Still, he and his Cuban colleagues developed an international reputation with their hurricane warnings. Even after Father Vizñes died in 1893, Cuba’s forecasts were more accurate compared to the ones from other countries.

ROMAN MARS: In contrast, the U.S. system was sluggish and conservative. Meteorologists around the country had to wire their reports to Washington D.C., where the central office would decide what was real and worth sharing. Warnings went out slowly–if at all. So, the public was frequently caught off guard when big storms arrived. And the Weather Bureau’s Caribbean weather station was run by a guy who thought tracking hurricanes was “a matter of divination.”

ALANA CASANOVA-BURGESS: And then things got worse. In 1898, at the end of the Spanish American War, the U.S. took temporary control of Cuba, which meant the Americans took control of Cuba’s warning systems. And instead of cooperating with their colleagues in the Caribbean, the Weather Bureau restricted access to telegraph cables and promoted their own West Indian hurricane warning systems instead.

ERIC JAY DOLIN: And a lot of that, as I described in the book, really had to do with the condescending attitude that the American meteorologists had towards their fellow meteorologists–and that was much to the detriment of the Americans.

ROMAN MARS: They paid the price almost immediately. In September of 1900, Cuban meteorologists warned of a storm that was going to intensify, turn into a hurricane, and head to the Gulf of Mexico.

ERIC JAY DOLIN: And the Americans were not paying attention to the valuable meteorological information that the Cubans were providing, and they missed some of the signs and information that the Cubans had been tracking. They knew that it was a hurricane. It wasn’t until the very last moment that the American meteorologist finally said, “Oh, this is a hurricane. By then, it was almost too late.”

ROMAN MARS: Galveston’s population was 38,000 people at the time, and as many as 8,000 people died. It’s one thing to note generally that a storm is coming. It’s another to forecast that it’s going to be a deadly calamity.

ALANA CASANOVA-BURGESS: And it would be decades before the U.S. began making real progress in understanding hurricanes.

ROMAN MARS: That big leap came from a pair of cocky World War II pilots. The two airmen–also in Galveston as it happens–made a bet to show how tough their planes were.

ERIC JAY DOLIN: And this was taking a plane deliberately flying it into a hurricane through the wall of a hurricane into the eye of the hurricane.

ALANA CASANOVA-BURGESS: If the plane could make it, they’d get a high ball. They described the flight as “being tossed around like a stick in a dog’s mouth,” but they did make it. And when they landed, a meteorologist from the base asked to go up next. And it caught on. The stunt turned into science.

ROMAN MARS: The Hurricane Priest, Father Viñes, would’ve probably loved this. By the early 1950s, these pilots and scientists form a cadre called “Hurricane Hunters.” They would fly directly into swirling storms, which gave them an unprecedented ability to observe hurricanes closeup.

ERIC JAY DOLIN: And instruments on board the planes would take measurements that could be relayed back to a land-based meteorologist or weather station with all of this data that can then be used by the meteorologist to help predict the path and strength of the hurricane.

ALANA CASANOVA-BURGESS: But we still didn’t have a way to communicate that forecast clearly and concisely or a way to show the public what warnings were actually based on to prove that they were worth heeding. That step was taken by the most trusted voice in broadcasting at the time, Edward R. Murrow.

ERIC JAY DOLIN: In mid-September of 1954, he decided to hop into a Hurricane Hunter plane and go and fly into the center of what was called Hurricane Edna, which was threatening the east coast.

EDWARD R. MURROW: Good evening. This tattered hunk of cloth is a hurricane flag…

ROMAN MARS: 1954 was an active year for hurricanes, and Edna was big news. Murrow showed the country what it was like to track a hurricane’s path toward landfall. This wasn’t a stunt, Murrow told viewers, it was a routine mission–a service from the United States Air Force to the United States taxpayer.

ALANA CASANOVA-BURGESS: Murrow, his cameraman, and a small flight crew climbed into a B-29 fighter plane along with one meteorologist. And there was Murrow–trying to improve the public’s understanding.

EDWARD R. MURROW: The general opinion up here seems to be that Edna is not going to behave like a lady, but we’ll find out about that…

ERIC JAY DOLIN: “The general opinion up here,” and that’s in the Hurricane Hunter plane, “seems to be that Edna is not going to behave like a lady.” It’s very 1950ish. And then the plane goes into the eyewall!

ROMAN MARS: Murrow was showing the whole country, including parts far from the coasts, what the immense power of the storms looked like closeup.

ALANA CASANOVA-BURGESS: What he describes into his microphone, above the roar of the engines and the storm–without even reading from a script–is beautiful. Being in the eye was like being in “an amphitheater surrounded by clouds.”

EDWARD R. MURROW: No sign of the sun except this dim illumination. The whole surface of the ocean is undulating, like some huge giant was shaking a carpet. Each huge wave seems to be dragging another along behind it…

ERIC JAY DOLIN: Wrapping up, in his studio, Murrow looked into the camera for his grand summation. and what he said is: “In the eye of a hurricane…”

EDWARD R. MURROW: In the eye of a hurricane, you learn things other than of a scientific nature. You feel the puniness of man and his works. If a true definition of humility is ever written, it might well be written in the eye of a hurricane.

ROMAN MARS: Murrow’s reporting helped the public feel the pure awe of being inside a giant hurricane. They could also see the enormous effort that went into tracking such a massive and dangerous phenomenon.

ALANA CASANOVA-BURGESS: A few months later, Congress set aside funds to establish the National Hurricane Research Project. And its first director was a meteorologist named Robert Simpson–that same meteorologist who was on that epic flight with Murrow.

ROMAN MARS: Over the next few decades, Simpson became the big name in hurricane research. In the early 1960s, he and his wife even led Project Stormfury, where the U.S. government tried to weaken hurricanes by releasing silver iodide into them. That didn’t work–obviously.

ALANA CASANOVA-BURGESS: Simpson and his colleagues were also trying to get a tighter grasp on hurricanes with enough time to warn the public about them. That meant communicating the forecast updates quickly and loudly.

ROMAN MARS: Back then, warnings for hurricanes described them in vague terms, like either “minor” or “major.” There was a system of using flags along coastlines to tell people one was coming, but that was about it. Here’s Simpson, as director of the National Hurricane Center, describing his quest for a much more effective public alert system.

ROBERT SIMPSON: You can’t order a model off the shelf and put it into practice. But we can, through our modern technology, keep closer in touch with a hurricane–be sure that we are not deceived.

ALANA CASANOVA-BURGESS: In 1969, a hurricane named “Camille” was stalled in the Gulf of Mexico.

A LADY CALLED CAMILLE: A lady called Camille is supposedly headed toward the Florida panhandle but–like any lady–perfectly capable of changing her mind…

ALANA CASANOVA-BURGESS: Simpson didn’t have a lot of information from the hurricane hunters until really late because they were off chasing another storm in the Caribbean. He also didn’t have a way to tell people in simple terms that this wasn’t just going to be a hurricane–it was going to be a hurricane.

ROMAN MARS: The National Hurricane Center put out alerts about Camille, which went beyond the simplistic language of existing warning systems. But those meteorologists ended up giving the public too much information.

ALANA CASANOVA-BURGESS: They described the storm as “extremely dangerous” but also a “tight, little hurricane,” which doesn’t sound so scary actually. And then they threw a lot of data at the public. They told people it had sustained winds of 150 or 160 miles per hour and it was moving 12 miles per hour. They reported that it had a barometric pressure of 26.81, and they compared that to a terrible hurricane in 1935 with a barometric pressure of 26.35 inches. And I’ve been reporting this episode for months, and I would really struggle in a crisis to tell you exactly what that comparison means.

ROMAN MARS: Camille’s wind speeds are now thought to have been 175 miles per hour when it made landfall. We don’t know exactly because the winds were so strong that they destroyed the equipment used to record them.

WWLTV: This scene here on the Mississippi Gulf Coast is almost like an endless nightmare–almost like an endless one-act play with some sort of a macabre ending.

ROMAN MARS: Today we would call Camille a Category 5 hurricane. It’s one of only four Category 5s to have ever made landfall in the U.S. Camille killed 256 people. The storm washed away roads and made entire buildings just disappear. People came back to their communities and found piles of debris where their homes used to be.

A LADY CALLED CAMILLE: And this is my first hurricane. I didn’t know enough to get out. And my house was under 12 feet of water, and I hope I never see nothing like this again.

ALANA CASANOVA-BURGESS: One woman was speaking to a news crew about her house not being where she left it. She turned around and saw it had been flung across the street, and she completely lost it.

A LADY CALLED CAMILLE: Mine was right there on the corner, and I don’t even see it… That’s my house! That gray one yonder–that’s my house!

ALANA CASANOVA-BURGESS: Bob Simpson talked about Camille in a weather channel documentary in 2012.

ROBERT SIMPSON: We learned a lot from that. I learned a lot–both as to what kind of meteorology and what kind of language we should use that would convince the people it was a time for them to go and not to argue about it at all.

ALANA CASANOVA-BURGESS: Touring the wreckage in the Gulf, Simpson heard over and over again that local authorities wanted to know how destructive a hurricane was going to be–not just numbers and readings but a quick sense of what those numbers would mean on impact. What people wanted was a key to understanding the potential aftermath.

ROMAN MARS: After the break, Bob Simpson teams up with a structural engineer to create the system for warning the public about deadly storms. In the wake of Hurricane Camille’s devastation in 1969, one thing was clear to meteorologists like Bob Simpson: the world needed a system for rating storms that would help people understand the threat and how to respond.

ALANA CASANOVA-BURGESS: Someone else was already working on this–a structural engineer in Miami-Dade County named Herb Saffir. He was developing a hurricane scale as part of a project for the United Nations and was based on structural damage from wind. It rated hurricanes 1 through 5 based on wind speeds and described what you’d expect from each level of intensity.

ROMAN MARS: Saffir sent his scale to the National Hurricane Center, where Bob Simpson made some tweaks, adding risks from flooding and storm surge, which is how much the sea level will rise.

ALANA CASANOVA-BURGESS: And in 1974, the Saffir-Simpson Hurricane Damage Scale was first published in a scientific journal, and the National Hurricane Center started using it for the public.

HUGH WILLOUGHBY: It’s just a couple of pages actually–exactly a couple of pages.

ALANA CASANOVA-BURGESS: Hugh Willoughby is the former director of NOAA’s Hurricane Research Division. He remembers when the scale was first published.

HUGH WILLOUGHBY: What the categories serve is it says the wind is going to blow really hard and you want to do something about it.

ROMAN MARS: The scale does a lot in those two pages. It goes through each of the five categories. It tells us that a Category 1 is probably going to damage mobile homes that aren’t anchored to the ground, for example. Stuff you leave outside are going to become projectiles.

ALANA CASANOVA-BURGESS: In a 2, you are going to get some widespread power outages. You can expect windows to get blown out and some signs are going to get blown away. A Category 3 is where things start to get really serious–with devastating damage. Trees will get uprooted or snapped, and power outages could last for weeks.

ROMAN MARS: The scale tells us that Category 4 or above is going to be catastrophic. Roofs are going to come off. Some walls might, too.

HUGH WILLOUGHBY: And Category 5 hurricanes are relatively rare. Category 5 means, “Holy Toledo, we better do something!”

ROMAN MARS: Cat 5s will bring power outages for months. The tops of industrial buildings will get swept off. Whole structures are going to get blown away.

ALANA CASANOVA-BURGESS: The categories don’t ask you to know about barometric pressure. They don’t ask you to think about whether these wind speeds are stronger than the wind speeds of the last hurricane your roof survived. The scale communicates exactly five numbers–1 to 5–that’s it.

HUGH WILLOUGHBY: Here’s the problem. 100 knots of wind sounds like a lot of wind. 150 knots of wind sounds like a lot of wind.

ALANA CASANOVA-BURGESS: Hugh Willoughby likes to talk in knots, by the way. 100 knots is like 115 miles per hour. 150 is like 172. That’s how meteorologists think about hurricanes–in these big numbers. But imagine using that to warn the public. That’s way too much math in the middle of a crisis.

HUGH WILLOUGHBY: And Saffir-Simpson Scale gets us away from there. It’s really useful for getting a single mom and her two kids to evacuate.

ROMAN MARS: For 50 years, we’ve had Categories 1 to 5 to keep things simple. The reasoning was it wasn’t necessary to go any higher. It’s all about the property damage you can expect from a hurricane.

ALANA CASANOVA-BURGESS: There’s a famous quote–famous to meteorologists, that is–from Bob Simpson, from a print interview he gave in 1991. He stuck to the scale only being about hurricane damage to buildings and infrastructure.

ROMAN MARS: Simpson explained that any storm with winds above 156 miles per hour or so, which is a Category 5, would be so awful–so devastating for buildings–that it’s a catastrophe no matter what. He said, “I think it’s immaterial. That’s the reason why we didn’t try to go any higher than that anyway.”

ALANA CASANOVA-BURGESS: Basically, once a building is totally destroyed, you can’t get more destroyed. And an open-ended 5 accounts for that. But lately there have been calls to change the scale anyway.

CNN: Hurricane Dorian has sustained winds right now of 185 miles per hour with gusts above 200. And according…

ROMAN MARS: Hurricane Dorian sat on top of the Bahamas in 2019, dumping rain for 48 hours. Although Dorian was technically designated a Category 5, everyone who saw it thought it was way bigger than a 5. And it was so intense that it introduced this terrifying question into the world–not just for meteorologists or researchers, but for everyone–a question about how we talk about hurricanes and even how we think about them.

CBS: As we see more catastrophic hurricanes like Dorian, should scientists consider adding a Category 6 to the hurricane scale?

ALANA CASANOVA-BURGESS: A Category 6 to capture how bad things are getting. Scientists say climate change means stronger storms are going to be more frequent and that they’re likely to intensify a lot more quickly. That’s true in the Pacific, where hurricanes are called typhoons or super typhoons. That’s also true of hurricanes in the Atlantic.

ROMAN MARS: Yes, we have seen a rash of huge hurricanes in the past. There were a bunch of them in the early 20th century.

ALANA CASANOVA-BURGESS: But in the last 50 years, the U.S. has been hit by ten hurricanes that were Category 4 or 5. And seven of those giant storms have happened just since 2017. It’s like we’re seeing a catastrophic hurricane nearly every year.

HURRICANE CLIPS: Hurricane Harvey, state of emergency… Tonight, Maria’s direct hit, devastating Puerto Rico… Tonight, across Texas and Louisiana, Hurricane Laura’s message loud and clear… Hurricane Ian making history as it’s making landfall–a super disruptive, very dangerous phase…

ALANA CASANOVA-BURGESS: This worsening trend is why some meteorologists have started to suggest expanding the Saffir-Simpson Scale to include a Category 6. That conversation spilled out into the open recently with a journal article that considered what it would mean to add a Cat 6. It got a ton of press attention. The paper was called The Growing Inadequacy of an Open-Ended Saffir-Simpson Hurricane Wind Scale in a Warming World.

RICHARD OLSON: The argument is that Category 5 has no top. It starts at 157 miles per hour–sustained speed–but where does it stop?

ALANA CASANOVA-BURGESS: This is Richard Olson, director of the Extreme Events Institute and the International Hurricane Research Center.

RICHARD OLSON: Home of the Wall of Wind.

ALANA CASANOVA-BURGESS: And he’s one of the people who thinks it’s really time to talk about updating the scale and maybe expanding it to include a Category 6.

RICHARD OLSON: You look at the science, and the science says, “Higher number of more intense storms.” Okay, well, let’s think about that in terms of a scale that was developed 50 years ago. It’s time to have that debate.

ALANA CASANOVA-BURGESS: He remembers watching Dorian’s path in 2019, when it looked like that hurricane would hit South Florida. It was going to be like Andrew all over again–only worse.

RICHARD OLSON: That brought it home. It was like a lightning bolt right between my eyes, and I said, “Okay.” I don’t know how to describe to the media what it feels like to be looking at sustained winds of 185 miles an hour, less than 30 hours from my house.

ROMAN MARS: Climate change has forced scientists to make other adjustments to their extreme weather warning systems. The Australian Bureau of Meteorology added two new colors, pink and purple, to their maps to convey record breaking heat. So, maybe a 6 would expand our vocabulary for this greater risk and drive home the urgency of climate change.

ALANA CASANOVA-BURGESS: And the Saffir-Simpson Hurricane scale is from 1974. Maybe it could use an update. It describes damage as though all structures are created equal, but of course that isn’t true. Some areas have more vulnerable infrastructure than others. You could have a Category 2 storm that gives you the long-term power outages of a Category 5. Besides, a lot has changed about how we build stuff. Maybe Bob Simpson’s reasoning–that it’s all the same damage after 5–just isn’t true anymore.

RICHARD OLSON: It’s not the same built environment as it was 30, 40 years ago.


RICHARD OLSON: I can’t believe that that’s absolutely true. Yes. Now, I feel really old. Okay. It just says to me that we need to have the academic, government, open kind of debate.

ROMAN MARS: But the National Hurricane Center–which administers the scale and is in charge of categorizing hurricanes–isn’t keen on adding a 6 to Saffir-Simpson. There’s a fear in the scientific community that expanding it would do more harm than good. And that’s less about screws and roofs than it is about people–what people will do when they’re told about risks.

ALANA CASANOVA-BURGESS: Many don’t evacuate for a 4 or 5–sometimes because they can’t and sometimes because they don’t want to. So if 6 becomes the highest, what would that mean for the public’s response?

ROBBIE BERG: It’s still hard to understand what are we trying to achieve with calling something Category 6. Is it meant to get people to do something different than they should be doing with a 4 and 5?

ALANA CASANOVA-BURGESS: This is Robbie Berg, the Warning Coordination Meteorologist for the National Hurricane Center. The official answer from the NHC right now is no to a 6.

ROBBIE BERG: And then I think the next question is: Where does it stop?

ALANA CASANOVA-BURGESS: Would they next have to add a 7?

ROBBIE BERG: Some of the social science has actually shown that when you have too many categories in a scale or too many–say–colors on a map, it actually becomes harder and harder for people to interpret that because, in our minds, it’s very hard to deal with too many categories. Five is a very good, nice, round number that the human mind can absorb and understand. And so I’ll just say that our point of view is that 4s and 5s are still catastrophic. What more is there than that? And nobody’s been able to answer that. There’s not another word beyond “catastrophic” that can categorize what that damage would be.

RICHARD OLSON: Totally understand that and totally understand why they’re saying let’s not run off in this direction too quickly.

ALANA CASANOVA-BURGESS: Again, this is Richard Olson, who directs the International Hurricane Research Center.

RICHARD OLSON: But I just go back to the fact that, if we’re seeing storms in the 180s or higher, I don’t want to be playing catch up with nature.

ALANA CASANOVA-BURGESS: So, Olson has been thinking about what kind of research the Wall of Wind can contribute to the debate. “We need to know more,” he says, “About what happens to our infrastructure at the further reaches of a 5.”

RICHARD OLSON: So the issue for us is testing at all levels–all intensities–of a storm. We have to be thinking about a facility that goes beyond the current capabilities of the Wall of Wind.

ROMAN MARS: That’s why they’ve gotten a big government grant to figure out how to build a bigger, more beefed up lab. One that will go up to 200 miles per hour and have a big water tank to simulate storm surge and waves, too.

RICHARD OLSON: It’d be quite large. Think of the Wall of Wind–10 times the size probably.

ROMAN MARS: They want to simulate the whole hurricane–not just the wind part–in order to figure out how buildings and infrastructure might be able to withstand stronger storms.

ALANA CASANOVA-BURGESS: And that kind of facility would actually do something that goes beyond Saffir-Simpson, which points to what may be the scale’s single biggest flaw. It doesn’t at all account for water. It doesn’t consider how much rainfall a hurricane might cause or the expected storm surge, which is the amount of ocean water that gets pushed inland by strong winds beyond what you’d get from a normal tide.

ROMAN MARS: The relationship between wind speeds and storm surge isn’t so simple. There are lots of complicating factors–like the angle of approach to the coast or what the continental shelf is like there–which is why the National Hurricane Center, which administers the scale, stripped water out of the scale in 2010. And yet…

HUGH WILLOUGHBY: Most people who die in hurricanes drown. Moving water–it probably accounts for two thirds of the property damage and almost all of the deaths– Well, 80% of the deaths. And that’s what we need to worry about.

ROMAN MARS: One way to address that would be to introduce an additional scale to warn people about flooding risk and storm surge. That would save more lives.

HUGH WILLOUGHBY: The forecasters take it personally when somebody gets killed; they just don’t like it at all, and rightly so. And the people that get drowned don’t like it either.

ROMAN MARS: And in fact, this is something the National Hurricane Center–the NHC–really struggles with when it comes to the Saffir-Simpson. It’s a simple shorthand, but in some ways it’s too simple.

ROBBIE BERG: It helps us to communicate that obviously a storm is strong when it gets to be 3, 4, or 5, but we have really started to shy away from using it for everything.

ALANA CASANOVA-BURGESS: Robbie Berg with the NHC says it was a big problem during Hurricane Florence in 2018.

ROBBIE BERG: Florence had gotten strong. It got to a major hurricane strength. It was reaching or heading toward North Carolina, and it began to weaken a little bit as it was approaching the coast.

ALANA CASANOVA-BURGESS: It weakened so much that it was no longer technically a hurricane.

ROBBIE BERG: But the hazards with the storm–the rainfall we were expecting and the storm surge we were expecting–was not going to change. It didn’t matter that the storm was weakening. The rainfall and the surge were still going to be very bad. So, we made a concerted effort that, in our communications, we did not say the storm is weakening.

ALANA CASANOVA-BURGESS: They wanted people to focus on the risks of storm surge.

ROBBIE BERG: And wouldn’t you know, as soon as we send out the advisory, we start getting notices on our phone. And what do you think the headlines were?


ROBBIE BERG: It’s weakening. It’s downgraded to Category 1. So, the messages that we were intentionally trying to avoid–they were still getting out there in the media because journalists were writing stories, and what they were attached to is the wind speed.


ROBBIE BERG: That’s not what I’m saying at all. It’s just that–

ALANA CASANOVA-BURGESS: No, no, I’ll say it.

ROBBIE BERG: There’s no one way that’s going to fix the problem entirely. So ,really our goal is to find ways that are going to serve the most number in the population that the most number of people are going to understand. And that’s just a very tricky place to get to.

ROMAN MARS: It won’t surprise you to hear that the warming climate is going to bring more and more storms. Forecasters say 2024 will be a hyperactive hurricane season with an abnormally high number of storms heading the North Atlantic. And we’re going into this season with extremely imperfect tools for communicating the risk. Again, here’s Hugh Willoughby.

HUGH WILLOUGHBY: Another thing… We have “hurricane watches” and “hurricane warnings.” Both began with W. They’re about the same length. Eh, there ought to be more psychological distance between them.

ALANA CASANOVA-BURGESS (FIELD TAPE): I agree! I can never tell what the difference is. Are they not just synonyms?


ALANA CASANOVA-BURGESS (FIELD TAPE): I thought I was really stupid.

HUGH WILLOUGHBY: Well, no. The social scientists, the anthropologists, the communicators, all these people–you want ’em talking to the people who do the meteorology so that you communicate it right.

ALANA CASANOVA-BURGESS: The Category 6 debate is what got me interested in the history of how we’ve assessed hurricanes and in the Saffir-Simpson Scale specifically. There have been a lot of headlines about expanding the scale to 6. There’s something visceral about that idea that gets people’s attention, and I totally get it. I feel it too. It’s both terrifying and compelling. Like, things are so bad–maybe we just need to find a new way to talk about this level of bad. It feels to me like we’re living in 6 times–not just with climate change, but with wars, with failing democracies, with a global health pandemic, and on and on. But there’s way less public discussion, I’ve found, about the fact that the scale doesn’t say anything about the deadly risk from water or even about the urgent need to update our building codes along the coast. When you think about it, those seem like pretty major blindspots. And what everyone can agree on is that we’ve got to address those shortcomings. As storms get more intense and more frequent, we need a system that rises to the occasion–and not just another word for “catastrophe.”

ROMAN MARS: 99% Invisible was produced this week by Alana Casanova-Burgess. Edited by Christopher Johnson. Mix by Martín Gonzalez. Music by Swan Real. Fact-checking by Graham Hacia. Special thanks this week to Jeff Masters, Zak Rosen, the Edward R. Murrow collection at the Tufts Archives, and Jenny Lawton.Kathy Tu is our executive producer. Kurt Kohlstedt is the digital director. Delaney Hall is our senior editor. The rest of our team includes Chris Berube, Sarah Baik, Jayson De Leon, Emmett FitzGerald, Gabriella Gladney, Vivian Le, Lasha Madan, Jeyca Maldonado-Medina, Neena Pathak, Kelly Prime, Joe Rosenberg, and me, Roman Mars. Nikita Apte (PRONOUNCER HERE) is our intern.The 99% Invisible logo was created by Stefan Lawrence. We are part of the Stitcher and SiriusXM podcast family now headquartered six blocks north in the Pandora building… in beautiful… uptown… Oakland, California. You can find us in all the usual social media sites as well as our own brand new Discord server. There are, like, almost 4,000 people talking about architecture, talking about the power broker, and talking about all kinds of fun things. Please join us there. There’s a link to that, as well as every past episode of 99PI, at

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