Complex sentence: Tracking west-northwestward and then westward along a decaying subtropical ridge, Dora continued to intensify and was upgraded to a hurricane on August 8 based on the Dvorak technique.
Split into simpler sentences: Tracking west-northwestward and then westward, Dora continued to strengthen and was upgraded to a hurricane on August 8. Moving westward along a decaying subtropical ridge, Dora steadily increased to hurricane status on August 8, based on estimates through the Dvorak technique.