Climate experts increased the number of named storms they expect to see this season and upped the chances of above-normal activity as Mother Nature’s mood turns mischievous closer to hurricane prime time.
The Climate Prediction Center released its new forecast Thursday, which calls for 12 to 17 named storms, five to eight hurricanes and two to four major hurricanes of Category 3 or higher.
While the new prediction isn’t exceptionally higher than the May forecast, when 10 to 16 named storms were predicted, the center also increased the probability of a more active season to 35 percent from 30 and is calling for the busiest season since 2012.
Hurricane season peaks mid-August through mid-October.
“Conditions are in place that favor a more active season, and that’s the bottom line,” said Gerry Bell, lead seasonal hurricane forecaster for the center, which is part of the National Oceanic and Atmospheric Administration. “The outlook is really a reflection of what will happen during the peak months of the hurricane season.”
The demise of El Niño, weak vertical wind shear, feeble trade winds over the central tropical Atlantic and a strong west African monsoon are all contributing to the hike in storm numbers.
La Niña, once given a 75 percent chance of blazing onto the climatological scene, is now expected to be only a weak event by fall and winter with little to contribute to storm season. La Niña doesn’t necessarily encourage more hurricanes, but isn’t one to knock them down, either.
“La Niña does favor a more active season, but that’s only one player in the game,” Bell said.
An average hurricane season has 12 named storms, six hurricanes and three major hurricanes.
And it’s important to note that the new storm numbers include the five named storms that have already come and gone this year — Hurricanes Alex and Earl, and tropical storms Bonnie, Colin and Danielle.
That means up to 12 more named storms could form and six hurricanes if the high end of the center’s prediction holds true.
“The fear a lot of people have is we may get these storms fast and furious,” said Dan Kottlowski, a hurricane expert with the Pennsylvania-based AccuWeather. “We saw how things exploded across the Pacific a few weeks ago.”
In a five-week period beginning July 2, the Pacific has burned through five tropical storms and four hurricanes.
The Atlantic basin storms to date have been mostly unremarkable for the U.S. Hurricane Earl, which made landfall in Belize on Aug. 4 is being blamed for at least 40 deaths as its remnants triggered landslides in Mexico.
“Most of the U.S. is probably saying ‘What hurricane season?’” Kottlowski said. “But when you look at the numbers, we’re right on schedule to be near normal, and all we need is a couple more storms to be above-normal.”
The easterly African waves that serve as embryos for Atlantic tropical cyclones this time of year move off the coast every three to five days. They form when rainfall patterns shift in Africa, sending thunderstorm systems toward a ribbon of swift winds at about 15,000 feet called the African Easterly Jet. On the south side of that stream of air, the storms begin to rotate, spinning toward the coast like pinwheels.
But no storms are expected through at least next week. Kottlowski said most forecast models show debilitating wind shear — differences in wind speed and direction with height in the atmosphere — in the Gulf of Mexico and Caribbean.
“Those conditions will change,” Kottlowski said. “Everyone believes it will become quite active during the height of the season.”
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