Source: Sun Sentinel

A busy start to this year’s hurricane season — including this week’s short-lived Tropical Storm Don, which fizzled out on Tuesday night — could indicate that we’re in for a stormy few months, with an increased risk of a hurricane striking South Florida.

The season has produced four tropical storms so far, well above the number usually seen by this date, according to the National Hurricane Center. In an average year, it takes until Aug. 23 for the season to produce this many storms.

None of them developed into hurricanes. And the formation of these weather systems is such a complex business that random weather events could generate a freakishly busy start to an otherwise inactive season. But in this case, hurricane experts say, the prevailing climate conditions are favorable to storm formation and likely to remain so for the next few months.

One factor is the absence of El Nino, the warming of the eastern Pacific Ocean that suppresses hurricanes by producing high altitude winds over the Atlantic that tear up storms before they can get organized. Another is the unusually high temperature of the Atlantic, since warm water provides the energy for hurricanes.

“We have increased our forecast and now believe that 2017 will have above-average activity,” states the July forecast update of Colorado State University, one of the world centers of hurricane science.

“The odds of a significant El Niño in 2017 have continued to diminish, and most of the tropical and subtropical Atlantic remains anomalously warm. With the increase in our forecast, the probability for major hurricanes making landfall along the United States coastline and in the Caribbean has increased as well.”

The university’s forecast calls for eight hurricanes this year, up from six predicted in its June 1 forecast.

Philip Klotzbach, research scientist for the university’s Tropical Meteorology Project, said in an interview that conditions conducive to hurricane formation are likely to prevail through the season.

“Once you get into July and August, there’s not much that’s going to change,” he said.

Dennis Feltgen, spokesman for the National Hurricane Center, also cited the absence of El Nino in accounting for an above-average start to the season. NOAA’s Climate Prediction Center will issue an updated outlook for the 2017 Atlantic hurricane season on Aug. 9, he said, and the current forecast is for an above-average season.

The Atlantic hurricane season runs from June 1 to Nov. 30, with the peak running from late August through mid-September.

Tropical Storm Arlene opened the season unusually early, forming in the middle of the Atlantic in mid-April and the falling apart without threatening land. Tropical Storm Bret formed in mid-June and brought heavy rains to Venezuela and Trinidad and Tobago. Tropical Storm Cindy is the only one to strike the United States so far, making landfall in southwestern Louisiana on June 22 and killing two people.

The National Hurricane Center is currently watching Tropical Storm Don, which is heading toward the southeastern Caribbean Sea and northeast coast of South America. It is expected to weaken Wednesday as it reached an area of wind shear. The hurricane center is also monitoring a storm system in the Atlantic between Africa and South America that may strengthen but is expected to dissipate after that.

A busy start can indicate a busy season. The 2005 season was active from the beginning, with two tropical storms in June and three tropical storms and two hurricanes in July. The season continued with the catastrophic hurricanes Katrina and Wilma, ending as the most active hurricane season on record.

For South Florida, another ominous development this season has been the southerly course taken by most storms, said Jim Lushine, a retired forecaster and expert on South Florida weather. Storms typically veer north. And when they start out on a northerly track, this tendency takes them farther up the coast or into the open Atlantic, where they fall apart without ever striking land.

But the storms so far have taken a more southerly course, thanks to a high pressure system to the north that prevented them from moving north.

“The paths of many of the storms have been farther south this year than in other years, and that’s in general bad news for us,” Lushine said. “When storms come off that more northerly latitude they usually move up to the north before they reach South Florida. But when they come up from the south, that means they’re a little more likely to turn north just as they get in our vicinity.”