What time do they form?
Tornadoes can form at any time of year, but the conditions are most favorable in May. This is your basic "Tornado Season". On the Gulf Coast, it's earlier in the spring, but in the northern plains and upper Midwest, the season is late June and July. They also can occur at any time of day, but happen between 4-9 p.m.
Where do tornadoes form?
Most tornadoes occur right smack dab in the middle of the United States. This strip of the U.S is called "Tornado Alley". The states in Tornado Alley are North Dakota, South Dakota, Minnesota, Iowa, Montana, Indiana, Illinois, Ohio, Nebraska, Colorado, Kansas, Missouri, Kentucky, Tennessee, Oklahoma, Louisiana, Arkansas, and last but not least (by a long shot), Texas!
How do tornadoes begin?
Tornadoes begin in a severe thunderstorm called a "Supercell," which forms when a cold air mass and a warm air mass collide. Supercells last longer than your run-of-the- mill thunderstorm. The same property that keeps the storm going, also produces most tornadoes. Winds coming into the storm starts to swirl and form a "Funnel Cloud". The air in the Funnel Cloud spins faster and faster, creating low pressure around it. This sucks more air (and possibly objects) into it! (Hey! It's Bernoulli's Principle!!!)