The warning that I got from my brother was if you were in the desert and you saw rain in the mountains (like the picture below) to be on guard. You do not know you are in danger until you see a lot of bird movement, dust and a roar. Shortly after that, you are hit with quite literally a wall of water. I saw this first hand. There are many low lying areas in the desert that appear as nothing more than washouts. The water comes off the mountain sides and runs down these washouts. It will take anything and everything in it's path. Really weird and the signs along the road warning you not to stop really do exist.
Rick
