So much for South Florida’s brush with fall.
A tropical system swirling off the coast of Central America is expected to wrap the region in a muggy embrace this weekend, dumping heavy rain and returning temperatures to the 80s. Beginning late Friday or early Saturday, moisture from the system is expected to generate two to four inches of rain across South Florida, continuing through Saturday into the evening.
The system, which has lingered in the Caribbean all week, could still gain intensity as it moves north over warm ocean water and encounters weak wind shear, becoming a late season tropical depression or storm. But National Weather Service forecasters said Thursday the bigger threat to Irma-soaked South Florida is rain.
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“Normally several inches of rain is not a problem for us,” said NWS Miami meteorologist Robert Garcia. “But because of Irma and because people are still fixing their homes, it’s definitely something we want to bring attention to.”
Up to six inches of rain, or more, is possible, he said.
“Obviously it’s hard to pinpoint who might get that, but it wouldn’t be surprising to see six, seven or eight inches,” Garcia said.
For much of the week, the tropical system has produced widespread showers and thunderstorms across Central America, raising the risk of flash floods and mudslides. National Hurricane Center forecasters said the system’s proximity to the mountainous coast has so far kept it from intensifying, but they warn that could change as the storm moves north over warm ocean waters. Wind shear in the western Caribbean is also low. On Thursday afternoon, they gave the system a 30 percent chance of developing into a depression or tropical storm.
By Sunday, however, the cold front now chilling South Florida, and strong upper level winds tied to the front, are expected to stop any strengthening.
But meteorologists warn that the western Caribbean has a history of producing tricky late-season storms. Hurricane Mitch sprung from the region in 1998, killing more than 11,000 in Central America. In 2005, Hurricane Wilma hit Florida the week before Halloween, causing $17 billion in damage across the state.
For South Florida, more rain is not good news. The region remains saturated from Hurricane Irma and downpours over recent weeks, with about 50 inches of rain recorded so far this rainy season. That’s the highest amount since 1947, according to the South Florida Water Management District. The district has flushed nearly 250 billion gallons of water from Lake Okeechobee over the last year to protect the lake’s aging dike. And water conservation areas to the south that cover more than 1,300 square miles have been full for much of the summer.
District officials said Thursday they were lowering canal levels in advance of the rain, but also said most canals along the lower east coast have already been operating in their lower ranges as part of Irma recovery efforts.
To the west, water levels in the Big Cypress National Preserve are a half foot higher than average in late October, prompting the closure of roads and campgrounds, said spokeswoman Adrianna McLane.
The tropical system will also mean an end to South Florida’s sweater weather, Garcia said.
“Tomorrow morning will be another crisp fall day, but by Saturday we’ll be warming up pretty quickly,” he said.
Follow Jenny Staletovich on Twitter @jenstaletovich