Here is the passage again:
Day after day, thunderclouds rolled in during the early afternoon. Making Madison's grass thrive from all of the water. Her neighbors, however, prayed for a sunny afternoon so that Madison could finally mow the jungle that was the front yard.
The second part is a participle phrase fragment. Making, a present participle, starts the fragment. Notice that between making and water, there is no main clause. To be complete, a sentence must have a main clause.