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Folks misunderstand hurricane ‘cone of uncertainty,’ study shows. Time for a change?

Miami Herald logo Miami Herald 11/30/2022 Alex Harris, Michelle Marchante, Miami Herald

When there’s a hurricane coming, one iconic image fills TV screens and social media feeds: the cone of uncertainty.

But as shown by the confusion and criticism in the devastating wake of Hurricane Ian, which struck Southwest Florida as a Category 4 in September, that single graphic isn’t great at explaining what’s coming. And that’s largely because the general public doesn’t understand what the cone actually means.

This conversation comes up every year, but as the 2022 Atlantic hurricane season draws to a close on Wednesday, it may finally lead to a real shift.

New research from the University of Miami confirms what a lot of emergency managers already knew, that people don’t understand the cone, and the UM experts are working with the National Hurricane Center to reshape it. Meanwhile, one Miami-based TV station, WSVN Channel 7, has already changed the way it displays the cone for storms, starting with Category 1 Hurricane Nicole in November.

The renewed scrutiny comes exactly two decades after the hurricane center debuted the cone of uncertainty, sometimes called the cone of concern. It’s a simple tool, showing the projected direction of the hurricane’s powerful eye over five days, with the most likely path of the center shown as a thin black line, with a larger shaded area covering areas with a high potential of getting hit by the eye.

The closer a storm gets, the smaller that shaded area becomes. But the width of the cone at each day actually doesn’t change from storm to storm in any given season. There is a reason for that. The cone’s size is determined by error margins from past forecasts — but even then, there is some wiggle room. The formula only predicts a two-thirds likelihood that the storm’s eye will pass somewhere within that shaded area. Thus, the “uncertainty” attached to the forecast maps.

But because scientists have gotten so much better at predicting storms, parts of the cone have shrunk nearly in half in the last decade — from 172 miles at the critical three-day mark to 92 miles. The increasing success of the hurricane center forecasts also have given the public more confidence in the cone, or overconfidence, as Ian showed.

READ MORE:The ‘cone of uncertainty’ is getting smaller — but it still matters if you’re outside it

But the bigger problem is that many people in hurricane-prone areas misunderstand that graphic, research shows. A newly published study from UM found that most Floridians surveyed incorrectly believe the shaded area represents places that will be affected by the storm. It doesn’t. The eye is likely to wind up anywhere in that cone and the damage will extend far beyond.

“I think that was the big downfall for this past event with Ian. A lot of the public was focusing just on that one singular line rather than the whole cone of uncertainty,” said Athena Masson, a meteorologist and adjunct professor at Flagler College in St. Augustine. “The public begins to think ‘it’s going to be this tiny little area. Everything outside that is safe.’ That’s wrong.”

What went wrong in Ian

Days before Ian first formed as a tropical depression, the supercomputer-powered weather models forecasters rely on were singing in a chorus. They predicted a strong storm that hooked north through Cuba and approached Florida’s west coast. As it neared the coast, that confidence fell away with a storm on a path that can pose a particular challenge for forecasters and emergency managers.

With storms running perpendicular to the coast like Ian, a small, difficult-to-predict jog this way or that — common with hurricanes — can mean the difference between losing palm fronds and losing roofs.

From five days out, the cone of uncertainty was trained on Southwest Florida. But in those five days the projected center — the dark line at the center of the cone — shifted as far north as the Panhandle before swinging over the next few days back south for an eventual landfall in northern Lee County’s Cayo Costa. The thing is, that barrier island was always within the cone.

For a time, the focus from forecasters and the media was on Tampa Bay, which hasn’t had a direct hit from a hurricane in a century and could face catastrophic storm surge flooding when one eventually hits. Ahead of that risk, Tampa area leaders correctly called for evacuations.

READ MORE: SW Florida residents in Ian’s path had about a day’s warning to evacuate. Was it enough?

Some counties to the south did not, at least immediately. But as Ian drew closer and models pointed the biggest risks farther south, county emergency managers were forced to make a late call and many residents who based their decision to stay or go on earlier versions of the cone found themselves stuck.

Two days before the storm made landfall, the amount of time it takes for a successful full evacuation of hardest-hit Lee County, the center was pointed well north of Tampa. By the time officials in Lee called mandatory evacuations, residents had just over 24 hours to get out.

More than 100 people would eventually die as a result of the hurricane, many from drowning in Ian’s record-breaking storm surge. It’s impossible to know how many of those residents chose to stay behind because they misunderstood the risk they faced, because emergency officials called evacuations too late or because they simply couldn’t afford to leave.

“We’ve seen this every single year with every single cone — it always shifts,” said Masson. “But when you start losing immense amounts of lives, that really pushes the whole ‘the cone was wrong’ conversation into the spotlight.”

READ NEXT:Despite DeSantis’ claim, Ian’s cone forecast accurate, experts say

After the storm, residents and elected officials criticized the hurricane center’s forecast. Some leaders, like Florida Gov. Ron DeSantis and FEMA head Deanne Criswell, incorrectly said Lee County wasn’t in the cone days before the storm. The northern half of the county, where the storm made landfall, was always in the cone, but it was on the very southern edge. The worst damage of the storm happened well south of the eye.

Acting NHC Director Jamie Rhome addressed the concerns in a blog post days after the storm had dissipated, saying he was open to changing the cone in the future but he stood by his agency’s forecast.

“I think it’s clear that not everyone is aware of our message to focus on hazards, which usually extend well outside of the cone,” he wrote.

Rhome repeated that the hurricane center has tried to shift the focus in recent years away from the cone and toward the individual risks of an incoming storm — extreme rain, high tides, storm surge, strong winds, mudslides and tornadoes — that vary for different places in the storm’s path.

“All the recent additions to our forecast suite, including new storm surge warnings and maps, were driven by social science to help us communicate hazards — something the cone was never intended to do. The challenge is that not everyone has the time, bandwidth or desire to sift through all this information. The cone is simple and familiar to them, so they make assumptions, oftentimes subconsciously, about what it means,” he wrote.

Is a better cone possible?

While Hurricane Ian was a fresh reminder of the cone’s issues, Hurricane Nicole’s arrival about six weeks later was an opportunity to put those lessons into practice, at least for one TV station.

Miami’s WSVN Channel 7 Chief Meteorologist Phil Ferro said Ian’s “messaging failure” made it clear a change was needed.

“We did not want to see that happen again,” Ferro said.

At WSVN’s North Bay Village station, discussions had already been brewing behind the scenes for about a year on how to best represent a system’s threat to South Florida. After Ian, WSVN’s weather team quickly got to work creating a new forecasting style, one that would put more emphasis on a storm’s hazards.

After all, storms and hurricanes don’t travel in a straight line, they’re more like a “spinning top,” wobbling right and left, said Ferro.

“A straight line is not the best representation of what a storm might do,” Ferro said.

After getting support from the hurricane center, Ferro thought they would roll out the new system for the 2023 Atlantic hurricane season, but then Hurricane Nicole formed in the Atlantic and pointed toward Florida’s east coast.

It was time.

People tuning in to WSVN’s forecast for Nicole still saw the cone of concern and got their forecast for rain, flooding and storm surge.

Gone from the forecast was the straight line representing Nicole’s center inside the cone of concern. In its place: a large shaded area showing the storm’s expected wind impacts, which stretched far outside the cone of concern.

“Hopefully, they’ll have a better grasp of what the threats may be,” Ferro said.

The WSVN team’s decision to switch up its forecasting happened fast, but change at the hurricane center will take much longer, although it’s already in the works.

A team of researchers from UM started studying the cone five years ago. Through online surveys of Floridians and in-person focus groups with Miami residents, they found that though the cone was the most accessed graphic on the hurricane center’s site, less than half of Floridians they talked to knew what it meant.

They also showed Floridians the hurricane center’s latest maps on potential storm impacts, which show how high winds will get and when, which spots are in for flooding rain and where storm surge may strike. Most respondents didn’t understand those graphics either.

“What we heard from folks is that they want to know what should they do, how should they prepare. And they rely on these types of communications to make decisions,” said Scotney Evans, an associate professor of community psychology at the University of Miami and one of the researchers on the team.

“Folks have gotten really used to the weather app experience and being able to locate themselves on the map and see what that means in relation to any type of risk that’s coming,” he said. “They’re always trying to figure out how to make it more proximal to their experience.”

Evans said his team used eye-tracking software to see how respondents looked at the NHC cone, as well as a few other test graphics they made. They also asked focus group members to describe their ideal graphic, which will inform their upcoming work to try and develop a new cone that shows all the potential hazards of the storm.

That may be tricky, said Masson, considering the laundry list of impacts a tropical storm or hurricane can have.

“How is someone going to portray all of that in one image?” she said. “Now, I’m just seeing a collage of rainbows that’s probably going to confuse the public even more.”

In his post-Ian blog post, Rhome alluded to this UM research and said he was open to making any suggested changes, but that it might not happen for a while.

“It’s tempting to want to engineer a quick fix to the cone, but we need to be scientifically disciplined and wait for the body of evidence to come forward, and then determine how to best apply it. We aren’t planning an immediate pivot away from the cone, and I don’t think the cone is ever going to go completely away,” he wrote.

©2022 Miami Herald. Visit miamiherald.com. Distributed by Tribune Content Agency, LLC.

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