 How does the weather system form?  Where does it form?  When (what time of year) does it occur?  What are the effects of it?  Why is it considered dangerous?

 A violent rotating column of air extending from a thunderstorm to the ground.  Warm moist air from the Gulf, and cold, dry air from Canada— instability is the result  form in areas where winds at all levels of the atmosphere are not only strong, but also turn with height in a clockwise or veering direction.

SCA LE WIND SPEEDPOSSIBLE DAMAGE Enhanced, Operational Fujita Scale F mph Light damage: Branches broken off trees; minor roof damage EFO mph F mph Moderate damage: Trees snapped; mobile home pushed off foundations; roofs damaged EF mph F mph Considerable damage: Mobile homes demolished; trees uprooted; strong built homes unroofed EF mph F mph Severe damage: Trains overturned; cars lifted off the ground; strong built homes have outside walls blown away EF mph F mph Devastating damage: Houses leveled leaving piles of debris; cars thrown 300 yards or more in the air EF mph F mph Incredible damage: Strongly built homes completely blown away; automobile-sized missiles generated EF5 over 200 mph F ujita Scale of Tornado Intensity

 Can be 600 miles across, winds 75 to 200 mph, last for about a week.  rotate in a counter-clockwise direction around an "eye" in the Northern Hemisphere and clockwise direction in the Southern Hemisphere  center of the storm or "eye" is the calmest part  only form over really warm ocean water of 80°F or warmer  atmosphere (the air) must cool off very quickly the higher you go  wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface

 produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail  basic ingredients used to make a thunderstorm are moisture, unstable air and lift (from fronts, seabreezes, or mountains)  most likely to happen in the spring and summer months and during the afternoon and evening hours  Every thunderstorm produces lightning, which kills more people each year than tornadoes.  A severe thunderstorm has damaging winds of 58 miles per hour or more, or hail three-fourths of an inch in diameter or greater

 sudden flooding that occurs when floodwaters rise rapidly with no warning within several hours of an intense rain.  slow moving thunderstorms  the #1 weather-related killer in the U.S.  Nearly 80% of flash flood deaths are auto related.  2 feet of water can float a large vehicle or even a bus

 Winter storms usually form when an air mass of cold, dry, Canadian air moves south and interacts with a warm, moist air mass moving north from the Gulf of Mexico.