Historic Storm Surge, Record Flooding

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(TNS) – Hurricane Ian came ashore with devastating near-Category 5 winds that peeled the roofs off homes and uprooted trees.

But for most of Florida, the greatest hurricane threat was the water.

The combination of epic storm surge along the coast and unprecedented rains inland flooded homes across a huge swath of the state. It’s the risk meteorologists have been sounding the alarm on for years — and the impact that scientists can most clearly say is made worse by climate change.

Final tallies aren’t in yet, but it’s clear Ian brought historic levels of storm surge from Key West to Naples to Fort Myers , with some spots seeing at least seven feet of water above dry land. And as Ian moved toward South Carolina , early reports showed the Atlantic ocean surging in at levels higher than 2016’s Hurricane Matthew with house-swamping levels of flooding in St. Augustine and Charleston, South Carolina.

On Sanibel Island , where Ian’s eyewall came ashore, the Gulf of Mexico rushed inland, sending floodwaters from a puddle on the street to the height of a stop sign in under half an hour.

Cole Mazza , a 25-year-old bartender, had to grab his cats Dolce and Gabbana and swim to safety in the pitch black as the surge rushed into his neighborhood in Fort Myers.

“A mini-tsunami hit and the water came up to my front doorknob. It was rising so fast I knew it was only a matter of minutes before I was underwater,” he said. “So I stuffed my cats in my carry-on suitcase, grabbed my sister’s ashes and jumped out the living room window.”

After dodging floating projectiles like fences and mailboxes, he found salvation in a neighbor’s home on stilts at the end of the street.

Gov. Ron DeSantis called it a flood of “biblical” proportions, and President Joe Biden warned it could prove one of Florida’s deadliest hurricanes.

“Storm surge is gonna be what this storm is remembered for,” said Jeff Berardelli , a meteorologist and climate specialist with WFLA in Tampa Bay . “It’s going to go down in the history books.”

Craig Fugate , former head of FEMA and director of Florida’s emergency management division, said on WLRN on Friday that Hurricane Ian’s surge was some of the worst he’d ever seen.

“This was probably the largest area of storm surge damage that we’ve seen in recent history,” he said. “People look at the images and say ‘that was wind.’ No, it was storm surge. That’s the power of water.”

Days before Ian made landfall, the National Hurricane Center was issuing dire warnings about the historic surge, with an extreme of 18 feet of surge expected in Charlotte Harbor .

It’s hard to say how close the hurricane center’s prediction was, because the storm surge broke some of the tide gauges in the area, but not before they registered at least seven feet of surge. It will take time before scientists can carefully measure the high water marks now staining homes, hospitals and businesses across Southwest Florida and analyze the true numbers.

“I wouldn’t be surprised if we got to 12 feet,” Berardelli said.

Record rainfall

But for most of the state, the impact they felt from Hurricane Ian was not surge, it was rain. The slow-moving storm crawled up the I-4 corridor dumping tremendous amounts of rain and flooding central Florida so badly that dozens of people had to be rescued from their homes by boat.

Initial estimates suggest as much as 19 inches in spots like Fort Myers , Sebring and Daytona Beach , very close to the maximum of 24 inches predicted by the hurricane center. one spot in New Smyrna counted nearly 30 inches of rainfall.

The Sarasota area saw more than 13 inches of rain in only six hours, Berardelli said. That ranks this rain event as something with a less than .1% chance of happening in a given year.

“It really obliterated the 1 in 1000-year criteria,” he said.

Berardelli said that although Florida soils are usually absorbent and can handle more rain than many other spots in the nation, central Florida had seen two to three times the normal month’s amount of rain recently and its soil was too soggy to hold much more.

That rain-driven flooding after storm surge can often be the second round of a storm’s one-two punch, said Arnoldo Valle-Levinson , a researcher with the University of Florida’s civil and coastal engineering department.

He pointed to 2017’s Hurricane Irma, where the greatest flooding in places like Jacksonville happened after the center of the storm passed by and the winds had subsided. The area saw five feet of storm surge, but after the winds died down, the river rose even higher, he said.

“These are two colliding forces that compound the effects of each other,” Valle-Levinson said. “Depending on the timing, the double punch can be fatal.”

The Peace River in Arcadia surged 10 feet higher in two days, soaring past the 20-foot record and is expect to reach nearly 24 feet high over the weekend. The overflowing river invaded people’s homes, leading to high water rescues by police days after Ian made landfall. It’s not expected to return to its normal level of around 12 feet for over a week.

Water has been the no. 1 killer in hurricanes for years, accounting for 90% of direct deaths in storms for the last sixty years, according to the NHC .

In Hurricane Florence, which sat and poured rain on North Carolina for days in 2018, 22 people died in the floodwaters. Hurricane Ida, another rainmaker, swept from Louisiana , where it made landfall as a Cat 4, to New York last year and killed 87 people. Most of those deaths happened in the northeast, which saw intense flooding.

Early reports of the more than 20 deaths from Hurricane Ian suggest many could be due to storm surge.

It’s why some scientists have advocated for a new approach to categorizing storms, since the category 1 to Category 5 Saffir-Simpson scale only measures wind speed. Even “just” Category 1 storms can cause tremendous damage with storm surge and flooding, like Hurricane Fiona in Puerto Rico earlier this month.

“We get all geared up — as we should — for Cat 3, 4, 5, but often the most impactful in terms of rainfall can be a tropical storm,” Marshall Shepherd , director of the University of Georgia’s atmospheric sciences program, told the Herald in June.

That’s part of the reason the National Hurricane Center has said it’s shifting its messaging away from categories or even the “cone of uncertainty” to focus on impacts, which as Ian showed, stretch far beyond the cone.

Hotter planet, higher risk

Another factor in the increasing danger of water in a storm is the fact that the world is warmer than it once was due to human-caused climate change.

Figuring out exactly how climate change has affected or will affect hurricanes is an extremely tricky business, because there are so many factors beyond warm water or air that impact storms. However, the two impacts researchers are most confident climate change effects are storm surge and rain.

Storm surge is when water is pushed ashore by a storm’s high winds. As sea levels rise and communities stay put, there’s physically more water available to flood them when a storm rolls through.

“All other things being equal, that rising sea level at the coast is leading to greater inundation risk during hurricanes and other storms,” said Tom Knutson , a senior scientist at NOAA studying climate and hurricanes.

The other relatively simple connection to make is that warmer air can hold more water, which makes it easier for storms to wring out even more rain. For every 2 degrees Fahrenheit of warming, we see about 8% more moisture in the atmosphere, and the world has warmed at least 2 degrees Fahrenheit since pre-industrial times.

The world’s top climate scientists have linked extreme rainfall to climate change with one of their highest levels of certainty.

“There’s no doubt about that and there’s no controversy about that,” Berardelli said.

One study of the 2020 hurricane season found an average 8% increase in 3-day rainfall totals for hurricanes, and a 5% increase for tropical storms.

The lead author, Kevin Reed , an associate professor in the school of marine and atmospheric sciences at Stony Brook University , said they also found that a hotter planet increased the rate of rainfall as well. In the 2020 season, his study showed that 3-hour rainfall rates increased 10% or higher for tropical storms and hurricanes.

“If you experience a similar storm in the future it’s going to rain more because of climate change,” he said. “If you had 30 inches of rain, you could say over 2.5 inches of that rain was due to climate change, meaning it would not have rained as much if we hadn’t heated the planet.”

Reed and his colleagues also produced a rapid study of Hurricane Ian on Thursday that suggested that it too saw a 10% increase in extreme rain rates due to human-caused climate change.

“The reality is we don’t need formal attribution post hurricanes to prove climate change impacts the storm. We live in a world that’s over 1 degree warmer, there’s no doubt that hurricanes have changed in some respect because of climate change.”

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( Miami Herald staff writer Linda Robertson contributed to this report.)

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