Outburst flood

An outburst flood is a big and sudden flood that happens when a natural dam (like a wall of snow, ice, and rock) is broken and lets a lot of water flow out at once. Outburst floods are dangerous because they happen suddenly and send a lot of water and debris (things like mud, rocks, and trees) rushing down the valley. They can damage land, buildings, and roads, so it's important to be prepared for them in case they happen in your area.