The 2017 hurricane season, already forecast to churn out more storms than usual, is likely to get even busier.
On Wednesday, the National Oceanic and Atmospheric Administration increased its forecast, just as the season peak nears, calling for 14 to 19 named storms, five to nine hurricanes and two to five major hurricanes with winds topping 111 mph. That’s slightly above the 11 to 17 named storms and two to four major hurricanes predicted at the start of the season.
“What’s different is these conducive conditions are now in place. We had expected them to develop as the season went on, which is why the May forecast called for an active season,” said Gerry Bell, NOAA’s lead hurricane researcher. “These conditions will persist.”
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Bell said weaker wind shear that can smother a tropical cyclone, weaker trade winds that steer systems and winds off the African coast will likely drive up the number and intensity of cyclones. Sea temperatures across the region are also warm, about one to two degrees above normal, he said.
“These aren’t the warmest temperatures on record, but they’re certainly sufficient to favor a more active season,” he said during an 11 a.m. briefing.
The likelihood of an El Niño forming, which can suppress storms, has also decreased, he said.
Already, the Atlantic has generated more storms than expected, with six named storms. Franklin, which made landfall in the Yucatán on Monday, became the season’s first hurricane on Wednesday. That’s double the number of storms that normally form by early August and nearly half during an average six-month season.
While there had been speculation that a decades-long warming and cooling ocean pattern that can drive periods of active seasons was begin to fade, Bell said this season suggests it’s not ending. Bell also said conditions in the Caribbean and tropical Atlantic that historically served as precursors to busy seasons look favorable.
“What we’ve seen this season so far is three named storms have formed in this tropical Atlantic and Caribbean Sea region,” he said.
In addition to Franklin, National Hurricane Center forecasters on Wednesday were also keeping watch on a second system about 400 miles east of the Leeward Islands. While they don’t expect the storm to intensify over the next couple of days, as it rolls northwestward it will encounter better conditions that could kick-start a cyclone. Forecasters are giving the system a 40 percent chance of forming over the next five days.