Isaias strengthened Friday into a major hurricane as it headed toward the US Gulf Coast, where final preparations were being made for potentially life-threatening storm surges and high winds. The hurricane is forecast to make landfall late Friday somewhere along the Alabama-Florida line and create dangerous conditions in the Florida Panhandle, southern Alabama and southern Mississippi, the National Hurricane Center said. Rain began falling along the coast Friday morning, and tropical storm conditions were expected to begin early in the afternoon.