A flash flood is not necessarily a wall of water roaring down a canyon. Contrast that to general flooding which can take days or even weeks to develop. Never drive into water covering a road or highway. Most flash-flood deaths are automobile related. Hail damage to automobiles, roofs, windows and farm crops is staggering.
Large hail is also a threat to small mammals and it kills many birds.
No other act of nature can match lightning for its swiftness, beauty, or frequency. Lightning strikes the earth 14,000,000 times per year in the United States. Nationally, lightning claims more lives than any other weather event. In addition, lightning and lightning-caused fires result in 3.3 billion dollars damage annually. It is widely but incorrectly believed that heat lightning is somehow different from ordinary lightning.