Tornado climatology
The United States averaged 1,274 tornadoes per year in the last decade. April 2011 saw the most tornadoes ever recorded for any month in the US National Weather Service's history, 875; the previous record was 542 in one month. It has more tornadoes yearly than any other country and reports more violent (F4 and F5) tornadoes than anywhere else.
Disaster area
Tornadoes are narrow aggressively rotating mixtures of air that come from the base of a thunderstorm, being the most violent of storms. Tornadoes are usually hard to see unless they form a condensations funnel made from:- dust, water droplets and debris. Tornadoes take place in several parts of the world, such as Australia, Europe, Africa but mostly occur in the United States, Argentina, and Bangladesh.