WASHINGTON (AP) — The U.S. Federal Reserve is expected to raise its key short-term rate by a substantial three-quarters of a point for the third consecutive time. Many Fed watchers will be paying particular attention to Chairman Jerome Powell’s remarks at a news conference afterward. When Powell spoke at an economic conference in Jackson Hole, Wyoming, last month he issued a blunt warning. He said the Fed’s drive to curb inflation by aggressively raising interest rates, he said, would “bring some pain” for Americans. Americans will likely get a better idea of how much pain could be in store.