Complex sentence: By that time, Lidia had weakened steadily, and emerged over the Pacific Ocean on September 3 as a depression and completed the transition into an extratropical cyclone about six hours later.
Split into simpler sentences: By that time, Lidia had weakened steadily, and emerged over the Pacific Ocean on September 3. Lidia weakened into a depression and completed the transition into an extratropical cyclone about six hours later.