Tropical systems stacking up; too soon to say where they’re going

National Hurricane Center

Right on schedule, hurricane season is heating up.

A tropical wave pointed toward the islands and South Florida is threatening to intensify while a second wave just off the coast of Africa became the season’s seventh tropical depression Monday. Meanwhile, Tropical Storm Fiona continues to trek east about 500 miles from the northern Leeward Islands.

In their 5 p.m. advisory Monday, National Hurricane Center forecasters said Fiona showed a burst of energy Monday afternoon, but they still expect dry conditions and strong wind shear to weaken the storm in the coming days.

Behind Fiona is another system that South Florida will be watching closely over the next few days: a tropical wave about 750 miles east of the Lesser Antilles that could bring heavy winds and rain to the islands as early as Tuesday. A hurricane hunter plane is scheduled to investigate the storm Tuesday, with forecasters warning the system could strengthen as it nears Hispaniola and the Bahamas later in the week.

While it’s too soon to tell which track the storm will likely follow, Weather Underground meteorologist Jeff Masters worried that even a weak storm stalling over warm ocean water could strengthen rapidly and bring dangerous flooding to the islands. After that, it’s too soon to tell.

So many systems moving across the Atlantic also help prime the system and pave the way for stronger storms, according to University of Miami meteorologist Brian McNoldy.

“The tropical cyclone conveyor belt between Africa and the Lesser Antilles can get preconditioned (moistened) by previous disturbances passing nearby — which may have succumbed to the relatively hostile early-season environment,” McNoldy wrote in his blog. “Fiona turned northward fairly early, but it did help to sweep out dusty dry air in the 1,700-mile-long channel between Africa and” the U.S. east coast.

The storms arrive just as the Atlantic reaches peak hurricane season between August and October, when 78 percent of storms typically occur. Forecasters had expected 2016 to be a relatively quiet year with the help of a powerful El Niño, but last month revised their forecast as the El Niño petered out.