PUERTO RICO – Tropical Storm Dorian threatened Puerto Rico with a direct hit at near-hurricane force on Wednesday and forecasters said it could strengthen further as it approaches the U.S. mainland.The storm was expected to pass over or near Puerto Rico, with landslides, widespread flooding and power outages possible in what is expected to be the first major test of emergency preparedness since Hurricane Maria devastated the island in 2017. President Donald Trump declared an emergency Tuesday night and ordered federal assistance for local authorities.“Practically the entire island will be under sustained tropical storm force winds,” said Roberto Garcia, director of U.S. National Weather Service San Juan, during a press conference late Tuesday.However, he said the forecast could keep changing, adding that late shifts occur with storms such as Dorian that do not have a well-defined centre.The storm earlier had been projected to brush the western part of the U.S. territory and the change in the storm’s course caught many off guard in the tiny island of Vieques just east of Puerto Rico, a popular tourist destination that now lies in Dorian’s path.“I’m in shock,” Vilma Santana said in a phone interview, adding that she’s relieved it’s not a hurricane. “Thank God it’s a storm.”A still-uncertain long-term forecast would have Dorian nearing Florida at hurricane strength by Sunday or Monday.Trump sent a tweet assuring that “We are tracking closely tropical storm Dorian as it heads, as usual, to Puerto Rico. FEMA and all others are ready, and will do a great job.”He added a jab at Puerto Rican officials who have accused the government of a slow and inadequate response to Hurricane Maria: “When they do, let them know it, and give them a big Thank You – Not like last time. That includes from the incompetent Mayor of San Juan!”Early Wednesday, Dorian was located about 60 miles (95 kilometres) southeast of St Croix, U.S. Virgin Islands. The U.S. National Hurricane Center said it had strengthened slightly, with maximum sustained winds of 60 mph (96 kph) while moving northwest at 13 mph (20 kph).The storm was expected to dump 4 to 6 inches (10 to 15 centimetres) of rain with isolated amounts of 8 inches (20 centimetres).It’s a forecast that worries many in Puerto Rico because blue tarps still cover some 30,000 homes nearly two years after Hurricane Maria. The island’s 3.2 million inhabitants also depend on an unstable power grid that remains prone to outages since it was destroyed by Maria, a Category 4 storm.Ramonita Torres, a thin, stooped, 74-year-old woman lives by herself in the impoverished, flood-prone neighbourhood of Las Monjas in the capital of San Juan. She was still trying to rebuild the home she nearly lost after Maria but was not able to secure the pieces of zinc that now serve as her roof.“There’s no money for that,” she said, shaking her head.The U.S. National Hurricane Center issued a hurricane watch and tropical storm warning for Puerto Rico, Vieques, Culebra and the U.S. Virgin Islands. A tropical storm warning also was issued for the British Virgin Islands, and a tropical storm watch was in force for the Dominican Republic from Isla Saona to Samana.Dorian earlier caused power outages and downed trees in Barbados and St. Lucia.Although top government officials in Puerto Rico said they were prepared for the storm and had sufficient equipment, a couple of mayors, including those in the western region, said they did not have enough generators or shelters that were properly set up.Jose Ortiz, executive director of Puerto Rico’s Electric Power Authority, acknowledged that the distribution system still has weak areas and could “suffer” under winds of 50 to 60 mph. However, he stressed the agency has the needed inventory, including more than 120,000 lights, 23,000 poles and 7,400 transformers.But Freddyson Martinez, vice-president of a power workers’ union, told The Associated Press that while the electric grid has improved in some areas, he worries about a lack of power line workers and post-Maria patches which feature lines affixed to palm trees.The island’s transportation secretary acknowledged that crews are still rebuilding roads damaged or blocked by Maria, more than 1,000 of which remain blocked by that storm’s landslides.Puerto Rico Gov. Wanda Vazquez urged those living in flood-prone areas or under a blue tarp to move into one of the island’s 360 shelters.Officials also said public schools and government offices would remain closed through at least Thursday.“We learned our lesson quite well after Maria,” Vazquez said. “We are going to be much better prepared.”In the U.S. Virgin Islands, which is still struggling to recover from hurricanes Irma and Maria, Gov. Albert Bryan Jr. closed schools and government offices and said he would implement a curfew until Thursday, adding that officials would soon open more shelters and were prepaing sandbags in all three islands.“The main threat in this storm is the water,” he said in a conference call early Wednesday. “We still have a lot of vulnerable people in the territory.”Some 1,000 customers in St. Croix and dozens in St. Thomas and St. John were already without power on Wednesday.Dorian was expected to move near the Turks and Caicos Islands and southeastern Bahamas on Thursday night or Friday.Meanwhile, Tropical Storm Erin formed well off the U.S. East Coast on Tuesday night, and the National Hurricane Service said the storm was forecast to move northward over the open Atlantic with no immediate threat to land.It was about 435 miles (705 kilometres) west of Bermuda and 265 miles (430 kilometres) southeast of Cape Hatteras, North Carolina, with maximum sustained winds of 40 mph (65 kph).