Flash floods happen when heavy rains unleash more water than the ground can absorb, causing that water to pile up and flow to low-lying areas

The heavy rain that turned a river in Texas into a raging wall of water was fueled by unique atmospheric conditions, according to meteorologists and climate scientists.

Flash flood alley is a curved-shaped region about 300 miles long and 50 miles wide in central/south-central Texas, extending from north of Dallas to southwest of San Antonio. Its location, weather patterns, and geology often combine to create devastating floods.