 Democratic Party rules say delegates that Mr. Biden won in the state primary should support him at the party's upcoming national convention unless he leaves the race. It's a long way from the United States, but Tropical Storm Burrell expected to pick up strength as it moves over open seas in the Caribbean. John Cangellosi, a specialist with the National Hurricane Center, expects Burrell to develop into a hurricane along the way. Our explicit forecast shows a strong Category 2, but this could easily be a Category 3 hurricane.