Complex sentence: Nora became a hurricane during the overnight hours when the cloud patterns improved, Nora began to move faster and closer to the west-northwest and early the next morning, Nora went under rapid intensification.
Split into simpler sentences: Nora became a hurricane during the overnight hours as the cloud patterns improved, as Nora began to move faster and closer to the West-Northwest. Early the next morning, Nora went under rapid intensification.