Nearly empty shelves where bottled water is normally displayed at a grocery store as Tropical Storm Dorian approaches

A man boards up the windows of a beach restaurant in the tourist zone of El Combate as Tropical Storm Dorian approaches.

A man fixes the tin roof of a stilt house on the water as Tropical Storm Dorian approaches.

Puerto Rico was bracing early Wednesday for the arrival of Tropical Storm Dorian, which is expected to become a hurricane before threatening the Bahamas and the US, according to forecasters.

Dorian was packing sustained winds of 60 mph as of 5 a.m. as it churned northwest at 13 mph on its path toward Puerto Rico and then the British Virgin Islands, the National Hurricane Center said.

Tropical storm conditions are expected in parts of the Dominican Republic late Wednesday and Thursday, with rainfall of up to 10 inches possible in some areas.

The storm’s exact path remains very difficult to predict, but forecasters say almost all their models suggest Florida residents should keep close watch as the system approaches the US coast this weekend.

A change in Dorian’s course concerned many across Puerto Rico, where about 30,000 homes still have blue tarps as roofs nearly two years after Hurricane Maria.

The US territory’s 3.2 million inhabitants still depend on a shaky power grid that has remained susceptible to outages since it was destroyed by the deadly Category 4 storm, which killed almost 3,000 people.

The White House — which was assailed over its response to the 2017 hurricane — said President Trump approved an emergency declaration late Tuesday for Puerto Rico, allowing for the Federal Emergency Management Agency to provide assistance in coordination with ongoing disaster preparedness efforts.

“We are better prepared than when Hurricane Maria attacked our island,” Puerto Rico Gov. Wanda Vazquez said during a televised news conference.

Vazquez, who took office recently after political turmoil led to the resignation of her predecessor, said preparations for the storm were more than 90 percent complete, emergency shelters have been opened and schools have been closed.

With Post wires