By Brian Ellsworth

MIAMI (Reuters) -Tropical Storm Nicole gained strength on Tuesday as it churned toward the Bahamas on track for Florida’s Atlantic coast, where a hurricane warning was posted for nearly 250 miles of shoreline with millions of residents warned to hunker down and prepare.

Nicole, packing maximum sustained winds of 70 miles per hour (110 km per hour), will likely grow into a hurricane on Wednesday around the Bahamas before making U.S. landfall along Florida’s east coast north of Miami on Wednesday night or early Thursday, forecasters said.

A hurricane warning was posted for Grand Bahama Island, Bimini, the Berry Islands and the Abacos in the northwestern corner of the West Indies archipelago nation, the Miami-based National Hurricane Center (NHC) said.

A 240-mile expanse of Florida’s Atlantic shoreline from Boca Raton north to around Flagler Beach was likewise placed under a hurricane warning.

That stretch includes NASA’s Kennedy Space Center at Cape Canaveral, where a colossal new $14 billion moon rocket was rolled out to its launch pad last week for a debut test flight that had been planned for next Monday.

Although the rocket was built to withstand exposure to heavy rains and hurricane-force winds up to 85 mph, NASA said on Tuesday it was postponing the flight by at least two days to give launch crews extra time to deal with the storm.

NASA said it would keep the rocket moored to its launch tower through the storm rather than try to roll the spacecraft back to its hangar – a nearly 12-hour undertaking that would entail additional risks.

The NHC also issued storm-surge advisories for the northwest Bahamas and much of Florida’s Atlantic coast, warning that Nicole’s winds could drive treacherous waves into low-lying areas well beyond the shoreline.

“This is a life-threatening situation,” the NHC’s latest bulletin said.

Storm-surge flooding devastated swaths of Florida’s Gulf Coast when Hurricane Ian crashed ashore there six weeks ago, causing an estimated $60 billion in damage and killing more than 140 people.

On Monday, Florida Governor Ron DeSantis declared a state of emergency for 34 counties along the state’s Eastern seaboard, urging residents and businesses to take precautions necessary to protect life and property.

By Tuesday, forecasters made clear that Nicole was a formidable tropical cyclone continuing to gather strength, with tropical storm-force winds extending up to 380 miles from its center.

Some 18 million Floridians were estimated to reside within areas covered under NHC-issued watches and warnings on Tuesday.

Palm Beach County Mayor Robert Weinroth warned that heavy rains from the storm could contribute to urban flooding, which he said “will be worse during high tide, with a 2- to 4-foot storm surge possible.”

He urged residents to stock up on food and supplies and to help look after elderly neighbors and others living alone, adding that emergency shelters would open on Wednesday morning.

On its forecast track, Nicole’s center was expected to approach the northwest Bahamas on Tuesday night and move near or over the islands on Wednesday before it approaches Florida’s coast later in the day. Storm surge could raise sea levels along island coasts by up to 6 feet (1.8 m) above normal tide stage, the NHC warned.

Residents were preparing for the storm on Tuesday on the Bahamian islands of Abaco and Grand Bahama, which were battered by Hurricane Dorian three years ago.

Holmes Rolle, 54, of West Grand Bahama said he does not plan to leave his home or shutter the windows.

“I just believe that, at this time and with the type of storm, it just calls for some winds and plenty rain,” Rolle said in a telephone interview.

“It’s going to take more than a Category 1 hurricane or so to really move stuff and have them flying around.”

Forecasters said Nicole would likely sweep across central and northern Florida into southern Georgia on Thursday.

(Reporting by Brian Ellsworth in Miami; Additional reporting by Jasper Ward in Nassau, Joey Roulette in Washington, and Brendan O’Brien in Chicago. Writing by Steve Gorman; Editing by Aurora Ellis and Stephen Coates)

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