2. FUJITA TORNADO INTENSITY SCALE  F0: Gale tornado (40-72 mph); light damage.  F1: Moderate tornado (73-112 mph); moderate damage.  F2: Significant tornado (113- 157 mph); considerable damage.  F3: Severe tornado (158-206 mph); Severe damage.  F4: Devastating tornado (207- 260 mph); Devastating damage.  F5: Incredible tornado (261- 318 mph); Incredible damage.

3. DEADLIEST TORNADOES  The Tri-State Tornado Outbreak of March 18, 1925 killed 689 people in Missouri, Illinois and Indiana. Murphrysboro, Ill., had 234 of those deaths, and West Frankfort, Ill., had 127.  Other deadly tornadoes include the May 6, 1840 tornado which killed 317 people in Natchez, Mississippi; the May 27, 1896, tornado which killed 255 in St. Louis, Missouri. Tornadoes on successive days in 1936 killed 216 people in Tupelo, Mississippi, on April 5; and 203 people in Gainesville, Georgia, on April 6.

5. TORNADO ALLEY AREAS WHERE TORNADOES OCCUR MOST