Complex sentence: Five tropical cyclones were reported during the season, the earliest of which was first observed on August 19 and the latest of which dissipated on October 11; these dates fall within the range of most Atlantic tropical cyclone activity.
Split into simpler sentences: Five tropical cyclones were reported during the season, the earliest of which was first observed on August 19 and the latest of which dissipated on October 11. These dates fall within the range of most Atlantic tropical cyclone activity.