Five lessons of the extraordinary 2017 hurricane season
Posted May 28, 2018 11:10 a.m. EDT
(CNN) — Today marks the official beginning of the 2018 Atlantic hurricane season, which got off to an early start with Subtropical Storm Alberto making landfall in Florida on Monday.
While we anxiously await what's in store in the 2018 season, which experts believe could be above normal, take a look back at five lessons from the record 2017 hurricane season in the Atlantic.
Inland flooding is often the worst impact from a landfalling storm.
Though top wind speeds get the headlines and determine the hurricane's "intensity" via the Saffir-Simpson hurricane scale, it is often flooding that causes the most death and destruction.
According to the National Oceanic and Atmospheric Administration, inland flooding accounts for more than 50% of hurricane-related deaths each year.
The impacts often surprise residents because they can occur far from where a storm makes landfall and well after it has weakened.
Hurricane Harvey became the most extreme example of the threat that inland flooding presents when it dumped unprecedented amounts of rain (up to 60 inches) in and around the Houston area after making landfall along the Texas coast in late August.
Harvey's damage exceeded $125 billion, according to NOAA, ranking second only to Hurricane Katrina; it displaced more than 30,000 residents and damaged or destroyed over 200,000 homes and businesses.
Unfortunately, only about one-third of those losses were insured, according to Monica Ningen, head of property underwriting for the United States and Canada with the reinsurance company Swiss Re.
"Many people were likely surprised by the fact that a lot of the damage came from flooding rather than wind damage," Ningen said. "This lack of awareness may be one of the reasons why 85% of American homeowners don't currently have flood insurance."
Don't focus on the center of the cone.
Hurricane Irma provided a valuable reminder of often-repeated advice from the National Hurricane Center: "Don't focus on the skinny black line" at the center of the the agency's forecast hurricane track.
"The NHC forecast cone provides some information about where the center of the storm is likely to move based on our track forecast errors over the past five years," according to Michael Brennan, senior hurricane specialist at the National Hurricane Center.
"The cone doesn't provide any information about impacts from storm surge, wind, rain or other hazards, which often occur well outside the area included in the cone," Brennan said.
But many still focus on the center of the cone and the black line that connects the projected positions, basing their preparations and evacuations on only that information.
When powerful Category 5 Hurricane Irma was approaching Florida in early September, the forecast path from three or four days out showed the center of a major hurricane tracking up the eastern coast of the state.
Initial evacuations included Miami-Dade, Broward and Palm Beach counties on the eastern coast -- and a number of residents in those counties evacuated to the northern and western parts of the state.
But as the forecast evolved, the track shifted west, and it became evident Irma's center would track more up the western flank of Florida, prompting evacuation orders for Naples, Fort Myers and Tampa.
"During Irma, too much attention was paid to small changes in the official track forecast of the center as it shifted from the east coast to the west coast of Florida," Brennan recalled.
"Even 48 hours out, average track forecast errors are about 80 miles, and the southern Florida peninsula is only 50 or 60 miles wide, so everyone in southern Florida and the Florida Keys was at risk of seeing direct impacts from the core of a major hurricane."
Many on the west coast of Florida were surprised by the shifted track and were not prepared to evacuate.
Evacuations were further complicated by the added traffic from those who had evacuated southeastern portions of the state and found themselves still in the path of the dangerous storm.
"That's why everyone under a hurricane or storm surge watch/warning needs to prepare and follow the advice of their local government officials, even if the exact track forecast doesn't go right over their area," Brennan advised.
Underdeveloped areas are far more vulnerable to a hurricane's impacts.
Hurricane Maria, which moved through the southern Caribbean and made a direct hit on Puerto Rico, "was comparable to Irma in its maximum wind damage, but also similar to Harvey in the feet of rain it dumped across Puerto Rico," according to NOAA.
But the widespread devastation it left in its wake and the long-lasting toll it took on the island's infrastructure were unparallelled elsewhere in the United States during the 2017 season.
"Maria essentially crippled the entire infrastructure system in Puerto Rico, including the island's power grid, its water, transportation and communications networks and its energy facilities," Ningen said.
"The poor suffer disproportionately when a disaster strikes," writes Marcelo Guigale, director of financial advisory and banking for the World Bank. "They are more exposed, more vulnerable, and less able to recover."
Even before the hurricane, Puerto Rico was mired in economic despair, having filed the largest municipal bankruptcy just months before the hurricane ravaged the island.
The socioeconomic hardships endured by Puerto Ricans meant they were unprepared for a disaster like Maria.
Ningen says the focus needs to be on avoiding damage (securing roofs and protecting and maintaining infrastructure) as well as mitigating the impact (having insurance and financial reserves to cover post-storm efforts).
Though power returned to most customers in Florida a couple of days after Irma, it took months for Puerto Rico after Maria. In fact, six months after Maria hit, there were still over 100,000 Puerto Ricans in the dark.
Just because you get hit by one storm doesn't mean you won't get hit again.
If there was one theme to the 2017 Atlantic hurricane season, it might be "Oh, no, not again!"
Starting with Harvey in late August and lasting through Nate in October, hurricanes affected land seemingly nonstop. And several places in the Caribbean and US Gulf Coast had to deal with more than one.
The US and British Virgin Islands endured back-to-back Category 5 hurricanes in Irma and Maria within two weeks of each other.
The tiny Caribbean island of Barbuda, part of the nation of Antigua and Barbuda, was devastated by Hurricane Irma when it was at peak intensity of 185 miles per hour and then had to be completely evacuated only four days later as Hurricane Jose approached.
It was the first time the island had been without people in over 300 years, said the country's US ambassador, Ronald Sanders.
Building codes matter.
Floridians who lived through Hurricane Andrew in 1992 have horrible memories of surviving one of the strongest storms ever to hit South Florida, which left parts of the state devastated. There are now stricter building codes, such as prohibiting particle board and requiring fasteners on roofs.
"For the 2004 and 2005 hurricane seasons, we found that homes built to code in Florida experienced up to 70% lower wind losses compared to homes not built to code," said James Done, a project scientist with the National Center for Atmospheric Research's Mesoscale & Microscale Meteorology Laboratory.
Florida has some of the strictest building codes in the state, costing home builders an extra 45%, but the peace of mind may be worth it.
Take Irma: The category 4 storm was one of the most powerful Atlantic hurricanes on record. It blew across the Florida Keys with 126-mph sustained winds before slamming into Marco Island with 111-mph sustained winds. "We had flood experts and underwriters on the ground after the events, and it was striking to see images of how much better the newer buildings, built with stricter codes, fared," Ningen said.
Certain homes were total losses, while others a block away look untouched, roofs perfectly intact.
"Strong and well-enforced building codes are even more important, and maybe even more cost-effective, in this new era of stronger hurricanes," Done said.