Genesis 7:17 - 21 & 23

The flood continued for forty days on the earth; and the waters increased, and bore up the ark, and it rose high above the earth. The waters swelled and increased greatly on the earth; and the ark floated on the face of the waters. The waters swelled so mightily on the earth that all the high mountains under the whole heaven were covered; the waters swelled above the mountains, covering them fifteen cubits deep. And all flesh died that moved on the earth, birds, domestic animals, wild animals, all swarming creatures that swarm on the earth, and all human beings. Only Noah was left, and those that were with him in the ark.

The flood is an account of destruction and re-creation. God appears to use the natural weather forces to achieve his purpose for the world.