Two feet of water will carry away most automobiles and SUVs. As little as six inches of moving water can be dangerous. Fast-moving water causes major damage to roads and bridges. A road may look normal, but the pavement or support structures underneath may be missing. Attempting to drive too quickly across a low water crossing may cause the vehicle to lose contact with the road surface.
Heavy rains can reduce visibility to zero.
Many flash floods occur at night making it hard to see the danger. The strength of flash flood waters is the most deceiving element for drivers. Moving water has tremendous power to float and push anything in its path. Seemingly shallow water can tumble even large vehicles off the road. Destroyed car being towed out of Shoal Creek after the 1981 flood.