Thunderstorms produce flash flooding when very heavy rain falls in a short period of time. Flash floods occur quickly and inundate streets with rapidly moving water. You should never walk or drive a car into the flood waters. Instead, turn around or abandon your car and move to higher ground. Even six inches of fast moving water can knock an adult off their feet and two feet of water will carry away most automobiles.
Tornadoes are infrequent in Montana, but they can occur during a severe thunderstorm.
A tornado warning will be issued when a tornado has been spotted or it is highly likely to develop. You should take cover as quickly as possible. The safest location is in the basement or the lowest level of a house, preferably in an interior room, like a bathroom, hallway or closet. If you are outside and a tornado is approaching, lie flat in a ditch or depression and cover your head to protect yourself from flying objects. Large hail and strong winds can also occur with severe thunderstorms.