Take a look at this mudslide that occurred in Chamoson, Switzerland on August 7, 2018, after a hail storm in the mountains above the village. The people watching could actually hear the water coming down the mountain a few minutes before it arrived but I’m not sure they were expecting it to be a huge mudslide. Since there is a manmade channel for the water to run down when it rains they know this can happen but I doubt they were expecting this amount of mud to come down.