Apart from causing death and injury directly, tornadoes and blizzards can also cause floods. Naturally, floods are usually caused by heavy rainfall, but whichever way they are created, they can be very destructive. The most dangerous and dramatic ones are known as flash floods. In June 1976, hot air blew north from the Gulf of Mexico, bringing huge thunderstorms to the Big Thomson Gorge, where they released 10 inches of rain in six hours. All the mountain streams filled up and met at the Big Thomson Gorge.