Why a USF researcher says hurricane categories need an overhaul
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Tampa Bay saw firsthand last year the deadly and catastrophic impacts of storm surge and rainfall from hurricanes.
- Yet, the current rubric for measuring a storm's severity is based on wind, not water.
Why it matters: A University of South Florida geosciences professor wants to change that.
State of play: Jennifer Collins and a team of researchers from the Netherlands developed a scale in 2021 that takes into account rainfall and storm surge, in addition to wind, when assigning a numerical category to a storm.
- And in new research published last month, the team makes the case that their scale helps people better understand and prepare for a storm's primary risk.
What they're saying: "Times have changed. Our understanding has changed. Science has changed," Collins said.
- "I think it is the right time to make a change and to have these conversations."
How it works: Diverging from the early 1970s-era Saffir-Simpson Hurricane Wind Scale, Collins and company's Tropical Cyclone Severity Scale assigns individual scores 1-5 for forecasted wind speeds, rainfall totals and storm surge height.
- It also provides for a combined score that's no lower than the highest individual category.
- While the Saffir-Simpson scale tops out at 5, the newer scale can rise to a 6 in extreme cases.
Case in point: Take last year's Hurricane Debby.
- The cyclone was a tropical storm when it passed Tampa Bay and a Category 1 when it made landfall in the Big Bend region. That's small potatoes for the storm-worn Floridian.
Yes, but: The rain just kept falling, causing major flooding around rivers such as the Alafia, Myakka and Manatee.
- While Debby was never rated higher than a Category 1, Collins' proposed scale would've classified it as a Category 3: 1 for wind, 2 for surge and 3 for rain.
What they did: In the most recent research, Collins and her co-authors presented about 4,000 people who live in hurricane-prone coastal areas — including Florida — with hypothetical storms rated using either the current Saffir-Simpson scale or the newly developed scale.
What they found: Respondents who were exposed to the newer scale were better able to identify the main hazard and make decisions like whether to pick up sandbags to combat flooding or cover their windows to prepare for high wind speeds.
- Participants exposed to the newer scale were also more likely to evacuate ahead of storms where water, rather than wind, is the main hazard, researchers found.
- "Various participants … mentioned that they typically only evacuate for hurricanes of Category 3 and up, illustrating people's sensitivity towards a hurricane category and their evacuation intent," the authors wrote.
The bottom line: "That's why I think it's very important that we not be using (the Saffir-Simpson) scale anymore," Collins said.
- "It's misleading. It's underestimating the dangers."