2023 hurricane season: Fear rain as much as storm surge as climate change increases threat

Kimberly Miller
Palm Beach Post

For decades, most deaths in tropical cyclones were brine-choked drownings as saltwater surged over fringy coastlines tearing down beach homes and taking lives.

But the scarier threat now may be coming from the sky.

New numbers released at the Governor’s Hurricane Conference this month found that 57% of deaths directly attributable to tropical cyclones from 2013 through 2022 were from freshwater flooding caused by heavy rains. About 15% were from high surf or rip currents, 12% were from wind and 11% were from storm surge. Other causes included tornadoes, high lightning and unknown.

It’s the first time in a decade that the National Hurricane Center did a comprehensive tally on the cause of storm-related deaths. The last study covered the years 1963 through 2012. It found 49% of deaths were from storm surge, 27% were from freshwater flooding with 8% from wind.

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NHC Deputy Director Jamie Rhome, who also led the production of storm surge warning products, said the change in how people are dying in tropical cyclones may be attributable to a few things. The public probably has a better understanding of the dangers of surge with the addition of new graphics, watches and warnings.

At the same time, nascent research has tied climate change to heavier rainfall rates that can lead to dangerous flooding.

“We spent so much time on education and outreach on storm surge and it is working,” Rhome said. “The idea is that storms are producing more rainfall and, over urbanized areas, it’s a catastrophe waiting to happen.”

Vehicles sit in flood water at the Palm Isle apartments in the aftermath of Hurricane Ian, Thursday, Sept. 29, 2022, in Orlando, Fla. Hurricane Ian carved a path of destruction across Florida, trapping people in flooded homes, cutting off the only bridge to a barrier island, destroying a historic waterfront pier and knocking out power to 2.5 million people as it dumped rain over a huge area on Thursday. (AP Photo/John Raoux)

In recent years, 2021’s Hurricane Ida killed dozens of people 1,400 miles from where it made landfall in Louisiana. That included 48 people who drowned in freshwater flooding in New Jersey, New York and Pennsylvania. Most flooding victims were stuck in cars or swept away by fast-moving floodwaters. But 14 people drowned in their homes or apartments.

Hurricane Harvey in 2018 killed 68 people in Texas. At the time, it was the highest number of direct deaths from a tropical cyclone since 1919.  All but three of Harvey’s victims died from drowning in freshwater.

There were no storm surge deaths in Harvey.

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All five deaths in 2019’s Tropical Storm Imelda were from freshwater flooding. Earlier that season, Florence killed 22 people with 17 drowning in freshwater.

“People think of rain as something that happens all the time and not as a deadly hazard,” said NHC Director Mike Brennan.

And that may make it even more challenging to get the attention of people who are threatened by rainfall flooding. People who live away from the coast, may not see water produced by a tropical cyclone as a concern for them.

“So, now we have to work harder inland,” Rhome said.

In this photo provided by Orange County Fire Rescue's Public Information Office, firefighters in Orange County, Fla., help people stranded by Hurricane Ian early Thursday, Sept. 29, 2022. Ian marched across central Florida on Thursday as a tropical storm after battering the state's southwest coast, dropping heavy rains that caused flooding and led to inland rescues and evacuations. (Orange County Fire Rescue's Public Information Office via AP)

The rainfall concerns were underscored last year by research on the 2020 hurricane season published in the journal Nature Communications. Scientists found that human-caused global warming had increased hurricane extreme rainfall rates by 11% and extreme three-day accumulated amounts by 8%.

Storms may also be lasting longer over land because of higher moisture content from climate change, according to a November 2020 study published in the journal Nature.

“Global warming increases the rate at which ocean water evaporates into the air and increases the amount of water vapor the atmosphere contains when fully saturated,” wrote meteorologist and Weather Underground co-founder Jeff Masters in a Yale Climate Connections column about 2022’s Hurricane Fiona. “This result is about 7% more water vapor in saturated air for every one degree Celsius (1.8 degree Fahrenheit) of ocean warming.”

Fiona dumped 34 inches of rain in Puerto Rico.

Emerging research is also looking at whether climate change is breeding some of the most damaging hurricanes: the ones that stall.

Left directionless by weak or shifting upper-air patterns, these types of storms, including Harvey, Florence, and 2019’s Dorian, batter the same area again and again with torrential rains and unrelenting wind.

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Despite the overall percentage of storm surge deaths falling below those from freshwater flooding during the past decade, 41 people died from storm surge when Category 5 Hurricane Ian hit Southwest Florida Sept. 28. (Twelve people died from freshwater flooding.)

Still, Rhome said considering the number of people in harm’s way, Ian deaths could have been worse.

In 2018’s Hurricane Michael, which made landfall in Mexico Beach as a Category 5, 8,000 people were exposed to storm surge. Five died from it.

An estimated 157,000 people were exposed to storm surge during Hurricane Ian — 20 times more than in Michael.

“Storm surge isn’t just a nice puddle of water,” said National Weather Service meteorologist Robert Garcia during a Governor's Hurricane Conference training session. “It’s violent, turbid water coming at a continuously increasing pace.”

Kimberly Miller is a veteran journalist for The Palm Beach Post, part of the USA Today Network of Florida. She covers real estate and how growth affects South Florida's environment. Subscribe to The Dirt for a weekly real estate roundup. If you have news tips, please send them to Help support our local journalism, subscribe today.