Hurricane Dorian has ratcheted up to an “extremely dangerous” Category 4 storm as it slowly makes its way to the Bahamas and the east coast of Florida.

Millions of people in the Bahamas and Florida, including the state’s Walt Disney World and NASA’s Kennedy Space Centre, may soon be finding themselves in the crosshairs of the hurricane.

The US National Hurricane Centre (NHC) said on Friday night that Dorian had sustained winds near 130 miles per hour (215 kph), with even stronger gusts, and warned residents that it would carry “a life-threatening storm surge and devastating hurricane-force winds”.

The centre expected the hurricane to bear down on Florida early next week, but tropical-storm winds could begin as early as Sunday morning.

NHC projections showed Dorian hitting roughly near Fort Pierce, some 120 miles (190 kilometres) north of Miami, then running along the coastline as it moved north.

Tropical storm Dorian expected to strengthen to hurricane Show all 7 1 /7 Tropical storm Dorian expected to strengthen to hurricane Tropical storm Dorian expected to strengthen to hurricane Shoppers preparing for the arrival of tropical storm Dorian stock up on supplies at a supermarket in Bridgetown, Barbados, on 25 August 2019. The US National Hurricane Centre warned the storm was expected to strengthen to a hurricane by the time it reached Puerto Rico on 28 August 2019. REUTERS/Nigel R Browne Tropical storm Dorian expected to strengthen to hurricane Residents board up a pharmacy in Bridgetown, Barbados, 26 August 2019. AP/Chris Brandis Tropical storm Dorian expected to strengthen to hurricane Storm clouds gather as tropical storm Dorian moves towards St Michael Parish, Barbados, 26 August 2019. AP/Chris Brandis Tropical storm Dorian expected to strengthen to hurricane Nearly empty shelves where bottled water is normally displayed at a supermarket in Cabo Rojo, Puerto Rico, 26 August 2019. REUTERS/Ricardo Arduengo Tropical storm Dorian expected to strengthen to hurricane Hotel employees remove sun loungers from a pool area in Gros Islet, St Lucia, 26 August 2019. REUTERS/Andrea de Silva Tropical storm Dorian expected to strengthen to hurricane Empty shelves that are normally filled with bread are seen empty at a supermarket in Gros Islet, St Lucia, 26 August 2019. REUTERS/Andrea de Silva Tropical storm Dorian expected to strengthen to hurricane Tropical storm Dorian is pictured off the coast of Venezuela in this NASA satellite photo, 26 August 2019. NASA/Handout via Reuters

But meteorologists said the hurricane’s track remained uncertain and it was still unsure if Dorian would plough directly into Florida or take a sudden turn northwards and only hug the coast – as some computer models predicted.

“There is hope,” Weather Underground meteorology director Jeff Masters said.

The NHC said the hurricane could strengthen even further after it was upgraded to a Category 4 storm of the Saffir-Simpson Hurricane Wind Scale, which has five categories in total, raising fears it could become the most powerful hurricane to lash Florida’s east coast in nearly 30 years.

Category 4 storms cause “catastrophic” damage, snap most trees and power poles isolating residential areas and causing power outages. After a Category 4 storm “most of the area will be uninhabitable for weeks or month” according to an NHC description.

Donald Trump declared the state of emergency in Florida and authorised the Federal Emergency Management Agency to coordinate disaster-relief efforts.

“This is an extremely dangerous storm, please prepare and be safe!” he tweeted.

Some counties announced mandatory evacuations on Friday. Brevard County, which includes NASA’s Kennedy Space Centre, and Martin County officials announced residents of barrier islands, mobile homes and low-lying areas would be under a mandatory evacuation order beginning Sunday morning. Indian River County officials said they will recommend residents of barrier island voluntarily evacuate after hurricane warnings are issued.

Around the state, homeowners and businesses rushed to cover their windows with plywood. Supermarkets ran out of bottled water, and long lines formed at gas stations, with some fuel shortages reported.

“This is big and is growing, and it still has some time to get worse,” Miami resident Julio Vasquez told AP at a Miami fast-food joint next to a gas station that had run out of fuel. “No one knows what can really happen. This is serious.”

At a Publix supermarket in Cocoa Beach, Ed Ciecirski of the customer service department told AP that the pharmacy was busier than normal with people rushing to fill prescriptions. The grocery was rationing bottled water and had run out of dry ice.

“It’s hairy,” he said.

Monday 2 September will be Labour Day, a US public holiday that falls on the first Monday of September, and many travellers’ plans for the weekend also faced disruption.

Major airlines are allowing customers to change their reservations without fees, and cruise lines rerouted some of their ships.

But because of the uncertainty around the hurricane’s track, Walt Disney World and other popular resorts in Orlando have not yet announced closures. State authorities have not ordered immediate mass evacuations.

“Sometimes if you evacuate too soon, you may evacuate into the path of the storm if it changes,” Florida Governor Ron DeSantis said.

Early on Saturday, Dorian was some 510 miles (820 km) east of West Palm Beach and 340 miles (545 km) east of northwestern Bahamas and travelling west at some 10 mph (17kph).

Dorian is expected to bear down on the northwestern Bahamas by Sunday, where it could raise water levels by 15 feet (5 metres) above normal tide levels, bring huge destructive waves, between 250 and 400 mm of rainfall and a risk of life-threatening flash flooding.

Residents were rushing to stock canned food and bottled water, depleting supermarket shelves, while the sound of hammering echoed across the islands as people boarded up their homes.

“Do not be foolish and try to brave out this hurricane,” Prime Minister Hubert Minnis said. “The price you may pay for not evacuating is your life.”

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