Complex sentence: Alex marked the fifth-latest start to a hurricane season in fifty years; the latest start to a hurricane season since 1954 was Hurricane Anita of the 1977 season, forming on August 29.
Split into simpler sentences: Alex marked the fifth-latest start to a hurricane season since modern records began in 1954. The latest start to a hurricane season since 1954 was Hurricane Anita of the 1977 season, forming on August 29.