1.   From mid-August until late September, a parade of thunderstorm clusters emerges off the west coast of Africa.

2.   From mid-August until late September, thunderstorm clusters emerge off the west coast of Africa.

3.   Still cool ocean waters and strong high-altitude westerly winds will combine to generally squelch the development of any fledgling thunderstorm clusters.

4.   Still cool ocean waters and brisk westerly winds aloft will combine to generally squelch the development of any fledgling thunderstorm clusters.

5.   The heaviest rain will occur later Friday and Friday night from eastern Oklahoma to northern Arkansas where a series of thunderstorm clusters will pass over the region.

6.   The latest in a series of early morning thunderstorm clusters will develop in the vicinity of Iowa where a stream of very moist air intersects the warm front.

7.   Thunderstorm clusters that reach peak intensity in the middle of the night and cover thousands of square miles are called mesoscale convective complexes.

8.   Afternoon thunderstorm clusters will develop over southwest interior Puerto Rico to produce heavy rainfall and flash flooding potential.