Hurricane Matthew, the fiercest Caribbean storm in nearly a decade, strengthened as it barreled toward the southeastern United States on Thursday after killing at least 140 people, mostly in Haiti, on its deadly northward march. As Matthew blew through the northwestern Bahamas on Thursday en route to Florida's Atlantic coast, it became an "extremely dangerous" hurricane carrying winds of 140 miles per hour (220 kph), the U.S. National Hurricane Center said. That made it a Category 4 hurricane and it was likely to remain so as it approached the United States…