7. US Tornado
United States experienced a series of weather disasters in the year 2011which resulted in causality of six hundred deaths and the destruction of $1 billion. From 25th to 27th April alone US witnessed 362 tornadoes which took away the lives of 350 people in Alabama. The tornado in Alabama occurred with a speed of 175 miles per hour after the winter rainfall and snow, resulting in the saturation of land and raising water levels in the river. The losses were huge, exceeding $10.2 billion.