Florence poses increasing threat to U.S. on ‘unprecedented’ track

Sept 07, 2018
Busy time in the tropical Atlantic with Tropical Storm Florence (far right) and Invest 94L (center).

Florence posed an increasing threat to the East Coast on Friday as its strength seesaws and it forges a unique path in the Atlantic that defies decades of climatology.

The National Hurricane Center’s five-day forecast shifted Florence closer to mid-Atlantic states and has it reaching Category 4 power by early next week.

Brian McNoldy, a senior research assistant at the University of Miami’s Rosenstiel School of Atmospheric Science, said 79 named storms have passed within 200 nautical miles of Florence’s location since 1851 without coming near the East Coast.

“It would essentially be unprecedented in a hurricane this far north and east not to recurve north,” said Bob Henson, a meteorologist for Weather Underground. “But unusual does not mean impossible.”

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Florence has so far been steered west by the Bermuda High, but that high is forecast to retreat to the east over the next few days. At the same time, an unseasonably strong area of high pressure, which is more likely to form in deep summer than fall, will come out of Canada and develop over the western Atlantic early next week.

Florence may be able to zip north between the two highs, or it could get caught in the clockwise flow of the second one and continue west toward the U.S. coast.

“We understand the broad strokes, but the details count, and will make the difference between a landfall in the Carolinas, a track up the mid-Atlantic coast, or an early turn keeping the storm offshore,” said hurricane expert and Miami TV meteorologist Bryan Norcross. “It is simply too early to know.”

As of 5 p.m. Friday, Florence had 65 mph sustained winds and was heading west at 8 mph. The storm was 905 miles east-southeast of Bermuda.

For South Florida it means increasing coastal swells and rip currents beginning Tuesday with higher waves in the northern part of the state.

Florence was joined in the busy tropical Atlantic on Friday by tropical depressions eight and nine, and Invest 94L, which was identified between Bermuda and the U.S. in the hurricane center’s 2 p.m. forecast. The nearly stationary trough of low pressure has only a 20 percent chance of forming over five days.

Gordon is also hanging on as a tropical depression near Arkansas.

BOOKMARK The Palm Beach Post’s storm tracking map

“This time of year, it can just happen that things pop up,” said Falko Judt, a research meteorologist for the National Center for Atmospheric Research in Boulder, Colo. “I’m not surprised to see this much activity. It’s the peak of hurricane season.”

Tropical Depression Eight, which was forecast to become Tropical Storm Helene overnight, is just off the coast of Africa. It could briefly reach hurricane strength before weakening early next week.

Tropical Depression Nine, which is about 1,700 miles east of the Winward Islands, could become Tropical Storm Isaac over the weekend. It was near stationary on Friday, but is expected to start moving west over the weekend and reach hurricane strength next week.

Henson said no one should panic about Florence, but with the uncertainty in the models, anywhere on the East Coast is a possible target.

“It’s all still on the table,” he said.

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