If you think snowstorms are bad...

This article from USA Today gives some quick facts about the power and force of torandoes.
-First off, tornadoes are known to form in America's heartland, across ten states, including Colorado, Iowa, Ohio, and Indiana. This area is known as "Tornado Alley".
-Second, a tornado needs three things in able to form- unstable air, a lifting force, and lower to mid levels of moisture. Unstable air is needed because it will continue rising and a lifting force is needed to cause the air to being rising.
-Third, tornadoes have been known to occur in all fifty states.
-Fourth, strong tornadoes usually occur near the edge of an updraft, not far from a downdraft, where air is descending. Rain or hail occur in a downdraft so that is why the arrival of a tornado is usually announced by a downfall of rain or hail.
-Fifth, the tornadoes in Florida are considered weak, even though they have one hundred mile per hour winds. Most weak tornadoes last ten minutes or less and usually do not travel far, while violent tornadoes are known to last for hours and can travel more than one hundred miles.

And finally, tornadoes are measured in the Fujita scale (F0-F6), with six different levels.
F0-F1 tornadoes: 40-112 mph winds (weak)
F3-F4 tornadoes: 113-206 mph winds (strong)
F5-F6 tornadoes: exceeding 207 mph winds (violent)

The article can be read here:

http://www.usatoday.com/weather/resources/2006-04-03-tornado-basics_x.htm

Deadly Oklahoma Tornadoes

http://www.msnbc.msn.com/id/37110311/40533311

This article I read was about tornadoes that occurred last May in Oklahoma. Residents in Seminole were told by the scientists that twisters were predicted later that week. Supercomputers were able to predict up to the hour updates about the storms. The most recent line of storms may have had nineteen tornadoes throughout central Kansas and Oklahoma. The debris of this powerful line of storms include matteresses, dented appliciances, flipped cars, and broken furniture. Residents have expressed concern about water damage and the upcoming line of storms approaching.

Government website about Tornadoes

This "Tornado Guide" is from the National Severe Storms Laboratory and National Oceanic and Atmospheric Administration website. This article is about tornadoes gives a detailed description of the different types of tornadoes (weak, strong, and violent), how tornadoes form, the frequency of tornadoes, and tornado variations, such as, waterspouts. This article also has information and illustrations about how tornadoes form.  A section on myths vs. facts about tornadoes is also included in this article. Overall, this website and article do a good, detailed job on many subjects/parts of tornadoes and were very interesting to read.

http://www.nssl.noaa.gov/edu/safety/tornadoguide.html