Hurricane Sally is a slow-moving threat. Climate change might be why

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BAYOU LA BATRE, ALABAMA – Hurricane Sally parked itself over the Gulf of Mexico on Tuesday (Sept 15), churning slowly and lumbering at a sluggish pace toward land, representing a climate change reality that has made many hurricanes wetter, slower and more dangerous.

Sally’s outer bands unleashed a relentless rain that began in the morning and continued unabated all day and into the night, threatening to deluge coastal communities in Alabama and Mississippi. Meteorologists worried – and almost marvelled – as the storm pushed forward at a speed of just 3.2 kilometres per hour, shifting erratically in its path and intensity.

Scientists saw Sally’s stall over the warm waters of the Gulf as yet another effect of climate change in the United States, coming as wildfires along the West Coast have incinerated millions of acres and sent foul air into the atmosphere as far away as Washington, DC.

A scorching summer – made worse by the burning of fossil fuels, experts say – led to dry conditions that helped turn this year’s wildfires into the worst ever recorded.

Fires were still burning out of control in Northern California and the Pacific Northwest on Tuesday, and air quality in the region – some of the worst in the world – prompted the closure of some schools, parks and beaches.

With the authorities pleading with residents to stay indoors, the hunt for missing people continued in scorched communities. In New Mexico, scientists were investigating whether the deaths of huge numbers of birds were caused by the smoke plumes altering their migratory routes or poisoning them in the air.

And all this amid a hurricane season that is among the most active on record. Last month, Hurricane Laura tore across southwest Louisiana, leaving a trail of destruction and cutting electricity that has yet to be restored to many communities.

Climate change has made hurricanes wetter and slower, scientists have found. Recent research suggests that global warming – specifically in the Arctic, which is warming much more rapidly than other regions – is playing a role in weakening atmospheric circulation and thus potentially affecting hurricane speed.

A 2018 study found that since the middle of the 20th century, translation speeds of all hurricanes and tropical storms had decreased by about 10 per cent. Another study that year that focused on Atlantic hurricanes found that the average speed of storms near the North American coast had slowed by more than 15 per cent.

In Bayou La Batre, Alabama, where Sally was already turning roads into rivers on Tuesday, Ernest Nelson, a retired commercial fisherman, reached a similar conclusion as he sought refuge under a house raised 3 metres the ground on concrete pillars.

Storms were getting bigger and more intense, he said. Nelson, who had worked the water for decades, gave his basis for that belief: “No meteorologist. No college degree. Experience.”

On Tuesday, the National Hurricane Center reported that Sally’s translation speed, the rate at which it moves forward, was about 2mph (3.2kph), and that the storm was not expected to accelerate much as it moved northward in the Gulf of Mexico toward an expected landfall on Wednesday (Sept 16). It was stalling, in effect, as it approached the Mississippi coast.

But rather than serve as a source of comfort, its languid speed only intensified the unease: Sally is dangerous, meteorologists warned, precisely because it is so slow. Its lingering could translate into major flooding, with more rain than the region typically records over several months.

Hurricane Paulette, by contrast, was zipping along in the Atlantic on Tuesday with a translation speed of more than 25mph after passing Bermuda two days earlier.

Other recent hurricanes have also stalled. A year ago, Dorian crawled over the Bahamas for a day and a half, causing widespread destruction from wind and storm surge. And Harvey, perhaps the best-known – and most costly – example of stalling, was no longer a hurricane by the time it slowed near Houston in August 2017. It had been downgraded to a tropical storm, but still it inundated the city and surrounding communities with 4 feet (1.2 metres) or more of rain over several days.

As Sally churned in the Gulf, the conditions left many living along the coast perplexed and unnerved. No strangers to hurricanes, they weighed the risks of hunkering down against fleeing.

The confusion came from the storm’s apparent fickleness, as the forecast constantly evolved in recent days, with predictions that included reaching west of New Orleans or hitting Biloxi, Mississippi. On Tuesday evening, the forecast said it was continuing on a path aimed for Mobile Bay, Alabama, likely making landfall on Wednesday morning.

Still, officials and meteorologists said there was a measure of certainty in the threat that Sally posed. The rainfall could reach as high as 75cm in some areas from the Florida panhandle to Mississippi.

The rainfall would compound a storm surge that could reach as high as 1.8m around Dauphin Island and Mobile Bay on the Alabama coast, according to the National Hurricane Centre. Forecasters from the centre also warned of life-threatening flash floods.

“I can tell you from many years of experience and many times passed, I’ve seen streets and neighborhoods quickly fill up with 5, 6, 7 and even more depth of water in a short period of time,” Sam Cochran, the Mobile County sheriff, said during a briefing on Tuesday.

And if residents stay behind, he added, it might be “a couple of days or longer before we can get you out”.

A hurricane warning remained in effect for an area stretching eastward from Bay St Louis, Mississippi, near the Louisiana border, to Navarre, near the tip of the Florida panhandle – a distance that includes most of Mississippi’s and Alabama’s coastlines.

A tropical storm warning covered the area west of the Pearl River to Grand Isle, Louisiana – including metropolitan New Orleans – and east of Navarre to Indian Pass, Florida.

Officials urged people living along the coast and in low-lying areas to clear out, taking advantage of the storm’s snaillike pace to avoid being trapped in floodwaters.

Intense waterfalls of rain began pelting Mobile, an old port city of about 190,000 people, Tuesday morning. The streets were mostly empty, but many residents had chosen to stay home to ride out a storm that was expected to deposit more than 60cm of rain.

Alonzo Johnson, a high school football coach, was sitting on the front porch of the 80-year-old Craftsman home where he lives with his family south of downtown. There was nothing to do but watch the rain and see how high it would go. Johnson, 47, said that floodwaters had gone to the bottom of a stop sign across the street in the past. During Katrina, the water had lapped up to the top of his porch, about 60cm off the ground.

“We’re anxious,” he said. If the water gets high enough, the family would retreat to the back of the house, which is a bit higher. “We’ll find a safe space where we can get to praying.”

A Global Asset Management Seoul Korea Magazine

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