Tropical Storm Isaac lashed South Florida with its tail Monday, triggering widespread power outages and flash flooding alerts even as the storm grew stronger and slowed in its path to the Gulf Coast.

Four states were under a state of emergency along the Gulf of Mexico in anticipation of Isaac’s emergence as a Category 1 hurricane Monday night or Tuesday morning — Louisiana, Alabama, Mississippi and Florida. With landfall still uncertain, Republican National Committee Chairman Reince Priebus opened his party’s convention Monday morning in Tampa, then recessed until Tuesday less than two minutes later.

“Isaac expected to be a hurricane soon,” the National Hurricane Center said in its 8 p.m. advisory. It warned of a “significant storm surge and flood threat from rainfall expected along the northern Gulf coast.”

Maximum sustained winds were near 70 mph.

The National Weather Service predicted earlier that Isaac would make landfall as a Category 1 hurricane along the northern Gulf Coast late Tuesday night or very early Wednesday.

The core was in the Gulf but tropical storm-force winds extended outward up to 205 miles from the center, making for a miserable South Florida day for about 62,000 homes and businesses that remained without power due to damaged and downed power lines and transformers operated by Florida Power & Light.

“A lot of people get misled by not seeing a truck in their neighborhood,’’ said FPL spokesman Richard Gibbs. “I can tell you there are a ton of people working behind the scenes to get power restored.”

About 24,130 customers (out of more than 1 million) in Miami-Dade were without power in the early evening Monday, while in Broward about 21,570 customers (out of 874,500) were experiencing outages, according to FPL.

About 16,190 customers (out of 687,000) in Palm Beach were without power. The utility has about 2.4 million customers in the tri-county area. FPL crews were working since Sunday night to repair downed lines and blown transformers, said Peter Robbins, another FPL spokesman, adding that the overnight winds and rains made work difficult

Wind-wise, Isaac didn’t amount to much. But its stubborn stormy outer bands continued to drench Southeast Florida from Miami-Dade to Palm Beach counties, saturating the grounds and causing canals to overflow into the streets, creating hazardous driving conditions. West Palm Beach County got the worst of it — 12 inches of rain made for widespread flooding.

Broward Emergency Operations Director Chuck Lanza captured the mood on Monday afternoon when he said the weather had been “much worse today” than it was Sunday.

“We don’t want people out driving if they can avoid it,” Lanza cautioned as the National Weather Service issued flood alerts. “In some areas, you can’t tell where the street ends and where the canal starts. Its dangerous.”

The additional deluge came on top of rain that made the 24 hours from Sunday morning through Monday morning the wettest since Hurricane Mitch in 1998, said Gabe Margasak, a spokesman for the South Florida Water Management District.

Across the district, which stretches from Key West to Orlando, Isaac dumped an average of nearly 3.5 inches but some spots in Palm Beach County recorded up to a foot. Sunrise in Broward saw more than six inches. And that was through 6:30 a.m. — not including the squalls that continued to rush across the state from Isaac’s center some 200 miles away.