ORLANDO, Fla. — During the this week’s National Hurricane Conference in Orlando, a Colorado State University professor proposed a better a way to predict the damages of a devastating hurricane — do away with the Saffir-Simpson Hurricane Scale.
Hurricane specialist, Philip Klotzbach, spoke Tuesday at Orlando’s Rosen Centre hotel about his crusade in doing away with the famous wind scale in favor of measuring surface pressure, the force exerted on the sea surface by the air above, as a better metric to predict hurricane damages.
“Wind hasn’t worked recently,” said Klotzbach, a CSU meteorology professor. “It’s not bad but pressure actually does (predict) better.”
Klotzbach spoke Tuesday to a standing room-only event during the four-day biannual Orlando conference, which showcases experts, authorities and entrepreneurs from all over the country versed in climatology, emergency management and tropical phenomenon.
His pitch was simple: replace the wind scale for a pressure scale. Klotzbach is not the only person supporting a movement of using pressure over wind, and Tuesday was not the first time the CSU professor pitched the idea. During the 2020 hurricane season, Klotzbach and other meteorological scholars, published a paper about the subject, but it went largely ignored and overshadowed by a storm of a different nature — the COVID-19 pandemic, Klotzbach said.
“Frankly, I think to get attention, we need a large hurricane like a Hurricane Ike, which was a Category 2,” Klotzbach said. “People said, ‘Oh, it’s not a major hurricane, I’m not going anywhere.’ And then, you know, 15-20 feet of storm surge in the Baltimore peninsula, and all those people lost their lives.”
Last week, CSU released its predictions for an above-average hurricane season this year predicting 19 named storms.
The Saffir-Simpson scale, which ranks hurricanes based on wind strength from categories 1 through 5, was first made in 1971 by civil engineer Herbert Saffir and meteorologist Robert Simpson, according to the National Oceanic and Atmospheric Administration. Since then, the scale has become the most used tool in communicating a storm’s strength to the public.
“It became more than just the wind, it became kind of the overall damage that the storm was likely to cause,” Klotzbach said.
Earlier versions of the scale in the ‘70s do incorporate central pressure as a metric, but it was removed for reasons that aren’t clear.
The NOAA describes the Saffir-Simpson scale as an example of the types of damages associated with winds, but also acknowledge the scale doesn’t address other “potential” impacts for other hurricane-related hits such as storm surge, rainfall-induced floods, and tornadoes.
Understanding pressure is crucial to the Klotzbach’s argument. Pressure is what is largely responsible for storm surge — which the National Hurricane Center has said is the most deadly force a hurricane produces. In 2019, the NHC found that most people consider wind to be the greater destructive force in a hurricane’s arsenal, however that isn’t the case, said NHC’s storm surge specialist Cody Fritz.
“Historically, storm surge has contributed to about half of storm-related deaths,” Fritz said.
A study of storm damage between 2007 and 2021 found that Saffir-Simpson scale predictions mostly didn’t see much of a consistent relationship between forecasted wind and excessive hurricane damages, according to CSU. However, CSU found a very strong relationship between predicted pressure and damages to an area, Klotzbach said.
Consider a tale of two hurricanes: 2004′s Charley and 2005′s Katrina. Both were devastating storms, but measuring the wind speeds before landfall predicted Category 5 Charley as the more threatening storm. Katrina was measured in as a Category 3 storm before landfall.
“But if we look at the pressure for Katrina, it was much lower than for Charlie when it made landfall,” Klotzbach said. The lower the pressure, the bigger the storm and more widespread its winds tend to reach, which means not only is there a wider coverage of strong winds but also a greater exertion of storm surge.
Hurricane Charley was devastating for Southwest and Central Florida, but the storm only produced about 7 feet of surge. Katrina put New Orleans through 28 feet of storm surge.
“The levees failed in New Orleans and all the damage that caused was devastating, but even had the levees held in New Orleans, we had 200 fatalities in Mississippi from storm surge,” Klotzbach said. About 1,800 people in total died because of Katrina. Comparatively, Charley was responsible for 37 deaths.
Applying the surface pressure scale to Katrina would have labeled the storm as a Category 5 hurricane, according to Klotzbach. The same could be said for 2012′s Super Storm Sandy, which made landfall in New Jersey as an extratropical storm under the wind scale, but a pressure scale would’ve labeled it as a Category 4 hurricane.
So why do meteorologists include the wind scale in the public forecast? Opposition argue it’s because most people don’t understand what surface pressure is, Klotzbach said.
“But I don’t think most people really understand what wind is either,” he said.
There is misconception that when a major storm hits an area, anyone in neighboring communities would also be encountering major hurricane winds, said Michael Lindell a professor at the University of Washington. Lindell spoke Tuesday at the Orlando hurricane conference about hurricane risk perception.
“People who are 50 miles up the coast in tropical-storm-force winds might think, ‘Oh I’ve been through a major hurricane and it was no big deal,’” Lindall said. “But they haven’t really been through the brunt of the storm ... They misinterpreted the experience.”
Risk perception and communication was big topic at the Orlando hurricane conference — it’s also a big priority for the NHC — but Klotzbach thinks his recommendation of pressure as a public tool is an important way to highlight the danger a resident might face in light of a storm.
“There are other things to worry about besides just the central winds, you know? A larger storms means it’s going to have more storm surge,” he said. “There have been some crazy hurricanes in the past. And if we can prepare from (what we learned) in the past, it will definitely get us better prepared for what we might see in the future.”
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