MIAMI — Hurricane Irma may go down as the first hurricane to go viral.
Between Sept. 1 and 30, when both Irma and Maria swirled across the tropics, the National Hurricane Center website recorded over 500 million page views resulting in 9 billion hits. Seven billion were linked to Irma alone, the agency reported in a wrapup of the storm released Monday.
As Irma storm approached Florida in September, about 57 million page views were recorded in a single day. That surpassed the total for Hurricane Matthew, the first storm in a decade to trigger statewide warnings across Florida, for its 12-day duration.
Spokesman Dennis Feltgen, who maintains the agency’s Facebook page, said he knew Irma was exploding into a monster storm online the morning of Sept. 5.
Just after he posted an update warning the storm had grown overnight into a dangerous Category 5 storm as it approached the Leeward Islands, on track to becoming the strongest on record outside the Gulf of Mexico and Caribbean, comments and shares piled up. He was so amazed he later snapped a screen grab: more than 4 million total reaches.
“My jaw dropped,” said Feltgen, who started his career in meteorology when storm information was still sent by teletype to TV stations. “I’d never seen a million before, let alone 4 million.”
As the storm moved along the Leeward Islands and headed for the Florida coast, the audience for updates posted by the center grew, with about 200,000 users on the website looking at advisories posted every three hours. Twitter traffic was even higher with 98 million impressions, nearly three times more than Hurricane Harvey. By the time the storm fizzled out near Columbus, Ga., on Sept. 11, Feltgen’s Facebook posts had reached more than 18.9 million users.
The social media numbers were included in the center’s after-storm report, an analysis compiled for every tropical cyclone tracked by the agency. The report offers a look at the storm’s history and a tally of final wind speeds, storm surge, rainfall and other factors, and as an assessment of forecaster accuracy.
Irma made seven landfalls, four as a Category 5 storm, and hit Cuba as the first Category 5 since 1932. The hurricane first hit the U.S. mainland in the Lower Keys Sept. 10, before landing again near Marco Island later that afternoon.
Forecasters generally called the storm’s development correctly, the report said, although it intensified into a tropical storm sooner than expected. They also successfully predicted Irma’s track, with 30 to 40 percent fewer errors than the five-year average for forecasts. But they again struggled to predict intensity, in part because they didn’t expect the storm to spend as much time over Cuba, which weakened it.
Storm-surge warnings in South Florida, where water reached up to eight feet above ground level in the Lower Keys and six to 10 feet around the cape to Everglades City, were mostly accurate. But the impact on the west coast was overstated, the report said, because Irma came ashore farther south than expected.
And while it may have looked like Miami was drowning under the sweeping surge pushed ashore, the report concluded that parts of downtown were actually flooded by a combination of heavy rain, stormwater and seawater coming up through the city’s aging drainage system. Soil sampled two days after the storm around Brickell showed patterns that indicated surge could be blamed for flooding a block or two from the bay, but further inland it was caused by heavy rain that could not drain into the bay.
Including an analysis of social media is a relatively new aspect of the report. Matthew’s 2016 report made no mention of public postings. Online traffic for Hurricane Harvey, which moved for three days in the Gulf of Mexico before hitting Texas in late August, was summarized in a single sentence. Irma was a game-changer.
“We’re handling it the way it needs to be handled, but social media, as you and I both know, is a very powerful tool,” Feltgen said.
The increase in in hurricane-news consumption has also spawned a new generation of amateur forecasters that Feltgen warned should be viewed cautiously.
“There’s a lot of nonsense out there,” he said. “You can go online and find the spaghetti tracks and look at the eight, 12- and 16-day models and plot something and it looks like the real thing. … Sure, you have a lot of followers, but you could be leading people down the wrong path.”
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