Tropical Storm Hermine could ruin Long Island’s Labor Day weekend with high winds and storm surges, forecasters said, as it barreled across South Carolina on Friday evening.

The storm was heading northeast and packing maximum sustained winds of 50 mph, with some higher gusts, the National Hurricane Center said in its 8 p.m. update.

Hermine should travel through coastal North Carolina on Friday evening, and head offshore on Saturday afternoon, at which point the hurricane center expected it to strengthen.

Hermine, the first hurricane to strike Florida since 2005, “could be near hurricane intensity by late Sunday,” the National Hurricane Center said.

“Anyone along the U.S. East Coast needs to be paying close attention this weekend,” said Dennis Feltgen, a spokesman for the National Hurricane Center.

In Florida, Hermine’s main impact came in the form of power outages and damage from storm surges. A homeless man south of Gainesville died when a tree fell on him, Gov. Rick Scott said.

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An estimated 325,000 people were without power in Florida and more than 107,000 in neighboring Georgia, officials said Friday night.

The coast from the North Carolina-Virginia border to Bridgeport, Connecticut, could experience “life-threatening” flooding, the federal agency said in its latest update.

A South Carolina official says Hermine has spawned scattered reports of flooded roads, trees down and power outages but no major damage.

Emergency Management Division spokesman Derrec Becker likened it more to a bad summer storm than a hurricane.

Winds fell to tropical storm strength after the storm hit Florida as a Category 1 hurricane, while it moved across the Southeast.

By late Friday morning, the weather service had issued a tropical storm watch for Long Island and New York City, with a storm surge watch in effect for coastal areas.

The National Weather Service’s Upton office on Friday afternoon said: “The probability of Tropical Storm Winds reaching 39 mph to 57 mph increased to 50% to 70% for all coastal sections in the Tri-State Area.”

The National Weather Service cautioned its forecasts could change as the storm approaches.

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“There is still uncertainty with the track and intensity of this system,” the service said.

After stalling off the mid-Atlantic coast until Monday, Hermine could begin carving a “slow Northeast track” southeast of Long Island over the next two days, the agency said in its update on Friday evening.

The storm surge could cause moderate to major flooding after high tide on Sunday, which could continue for a few cycles. Hazardous seas, rough surf and dangerous rip currents also can be expected, the National Weather Service said Friday.

High tides, comparable to a nor’easter, could be particularly perilous for coastal Long Island and New York Harbor, forecasters said.

Storm surge could make flood-prone homes and businesses vulnerable and certain roads in coastal communities impassable, they said.

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Other impacts could include damage to marinas, docks and piers, with potential for small craft to break away from moorings and get lifted onshore, the weather service said. With storm surge and battering waves creating deep inundation, oceanfront areas could possibly see “structural damage to buildings, with several washing away.”

Rainfall is the toughest call that forecasters are facing, said Gary Conte, warning coordination meteorologist with the weather service’s Upton office.

With a sharp cutoff between areas getting little to no rain and those getting 15 inches, a small shift to the south in the system’s track could mean no rainfall at all for Long Island. A shift to the northwest could mean a “torrential downpour,” he said on a Friday morning briefing. Even “small movements can make a major difference.”

News 12 meteorologist Bill Korbel by email cautioned there “Still [is] a threat of significant coastal flooding from late Sunday through Monday.”

How much rain falls and how fast the winds blow will be determined by the storm’s path; if it heads east, that could lessen the impact on Long Island. In that case, “Rainfall will be limited to showers and should not amount to much. Winds won’t be particularly strong,” Korbel said.

However, those rain and wind predictions worsen if the storm shifts farther west and north, which “could increase rain, wind and flooding,” he said.

  • Because of deadly rip currents unseen in intensity since 10 or 15 years ago, swimming will be banned at New York City beaches on Sunday and probably on Monday, too, Mayor Bill de Blasio said during a news conference at the Office of Emergency Management.

“Do not, you know, even put your foot in the water on Sunday and most likely for several days thereafter,” the mayor said.

Bridges could be closed entirely, depending on the storm, though officials may also issue a voluntary advisory suggesting drivers avoid the crossings if the weather is less treacherous, said Transportation Commissioner Polly Trottenberg.

With Matthew Chayes and AP