FORT LAUDERDALE, Fla. _ South Florida is fully within Tropical Storm Isaias' forecast track as projections move it slightly more east.
Tropical Storm Isaias is forecast to approach the coast of Florida this weekend, according to the National Hurricane Center, with wind speeds possibly reaching as high as 70 miles per hour and some models predicting it could strengthen into a hurricane.
Still, there is much uncertainty regarding its strength and intensity even with the storm just two days away from Florida. Fluctuations in the forecast were expected in the hours and days ahead.
Isaias (ees-ah-EE-ahs) was about 50 miles southwest of Punta Cana on the eastern tip of the Dominican Republic late Thursday morning, about to embark on a potentially storm-shredding journey over the mountains of Hispaniola, the island composed of the Dominican Republic and Haiti.
Depending on how intact Isaias remains after traversing that terrain, tropical storm watches could be issued for parts of Florida as soon as Thursday, the National Hurricane Center said in its 11 a.m. EDT Thursday public advisory. A watch means tropical storm conditions are expected in a given area within the next 48 hours.
Isaias itself was still pretty disorganized. In satellite imagery, it had more of the classic buzzsaw shape inherent to cyclones than it did earlier in the week, but it was also still a bit of a large, drifting blob.
Contributing to the uncertainty was the storm's projected journey Thursday over the mountainous terrain of Hispaniola. Those peaks could rip the storm apart, rendering it disorganized and less powerful as it emerges in the Atlantic waters north of the island on its approach to the Bahamas.
Plus, strong winds on the storm's path closer to Florida could be a problem for the already disorganized storm.
"The intensity forecast remains challenging," the National Hurricane Center said in a forecast discussion on Thursday morning. "The structure of the storm is likely to be disrupted by its passage near or over Hispaniola today, and some weakening is likely."
After that, gradual strengthening was expected. But the track and timing were still subject to change. Many of the so-called spaghetti models were continuing to pull the track of the storm east and away from Florida.
"Although trend in forecast track is good for South Florida, don't focus too much on the exact track," a briefing slide from the National Weather Service Miami said. "Confidence on the forecast remains low and fluctuations/changes continue to be likely over the coming days."
Isaias, which became the ninth named storm of a busy 2020 hurricane season late Wednesday night, saw its forecast track make a small move to the east early Thursday, according to the National Hurricane Center, with the center of that track keeping the core of the storm slightly off the shores of South Florida.
Although the center of the forecast cone keeps the core of Isaias slightly offshore of South Florida, nearly the entire state remains in the forecast path.
The system is projected to remain a tropical storm for its foreseeable duration (maximum sustained surface winds ranging from 39-73 mph). Little change in strength is anticipated until landfall in Dominican Republic later today, with re-strengthening forecast on Friday and Saturday, the hurricane center said Thursday.
Top wind speeds of 70 mph were predicted in a forecast discussion Thursday, which is just short of hurricane strength. Some models show it at hurricane strength near the U.S., according to the NHC.
In the 11 a.m. advisory, the storm was moving northwest at 20 mph and was about 50 miles southwest of Punta Cana in the Dominican Republic with maximum sustained winds of about 60 mph.
It is expected to continue aiming northwest with a dead-center pass over Hispaniola (the island that comprises the Dominican Republic and Haiti), contending with mountains as high as 10,000 feet.
Isaias is expected to continue on a northwest track until it reaches Florida, where a turn north is anticipated.
"Isaias is forecast to be near the Central Bahamas Friday night and approach the Northwest Bahamas or southern Florida Friday night and Saturday," said the National Hurricane Center's 11 a.m. Thursday public advisory.
"Heavy rains associated with Isaias may begin to affect South Florida Saturday morning, the advisory also said. "This rain could result in isolated flash and urban flooding, especially in low-lying and poorly drained areas."
Tropical storm-force gusts could arrive in Florida as early as Friday night, but Saturday is much more likely, the National Weather Service's Miami office said. The wind field is massive, with tropical-storm-force winds extending up to 310 miles north from the system's center.
It also said that "ahead of any impacts from the (impending) tropical system, most of the rainfall this week will be over the interior and Gulf coast of southern Florida," with rain chances increasing for Florida's east coast on Friday.
There have been four other tropical storms so far this month: Edouard, Fay, Gonzalo and Hanna. Other named storms this year have included Arthur, Bertha, Cristobal and Dolly. Tropical Storm Arthur formed in mid-May, making this the sixth straight year that a named storm formed before the official start of hurricane season on June 1.
So far, Hanna has been the only hurricane of the season, striking Texas late last week as a strong Category 1 storm.
Virtually all estimates for this hurricane season predict an above-average number of storms, due to unusually warm ocean temperatures and global climate factors that are likely to reduce the high-altitude winds that can prevent the formation of hurricanes. On July 8, Colorado State University issued a slightly more pessimistic outlook for hurricane season than its earlier forecast, upping the number of named storms from 19 to 20.
