Complex sentence: It was the first Category 5 hurricane in the Atlantic since Hurricane Felix in 2007, which had a similar trajectory, each causing catastrophic damage and a humanitarian crisis in Haiti as well as widespread devastation in the southeastern United States.
Split into simpler sentences: It was the first Category 5 hurricane in the Atlantic since Hurricane Felix in 2007. Matthew and Felix had similar trajectories, both causing catastrophic damage and a humanitarian crisis in Haiti as well as widespread devastation in the southeastern United States.