What are the weather conditions that makes it favorable for tornado's?
396017
In the US Midwest, tornadoes are usually formed when a cold, dry air mass moving south from Canada collides with a warm, moist air mass moving north from the Gulf of Mexico (or Baja California, or the Atlantic, or what have you). \nThis produces large thunderstorm clouds known as supercells, which can produce heavy rains, hail, and tornados. \nTornados are formed in areas of the supercell called mesocyclones; which draws air into the storm. When you hear meteorologists talk about the "hook echo" on the radar, they're pointing out the mesocyclone. The best simple explanation (so far) for why the tornado starts to rotate is the phenomenon of vertical wind sheer, where wind changes direction at different elevations.\nSo, if you have access to a weather radar; you can see hook echos like the one below. If you have a wind velocity view (some do, some don't), look for a large difference in wind speed and direction around that hook echo.
835940
Tornado, lasts minutes.  Thunderstorms hours, Blizzard hours to a day or so.  Hurricane, day to several days.
1085318
There are a couple reasons.  First off, Texas is the second-largest state in the US, next to Alaska.  So, there is more area in the state for tornadoes to occur.\n\nSecondly, Texas is right in the heart of Tornado Alley.  This is a place in the continental US where the airflow is just right for supercell thunderstorms (tornado-causing storms) to form, with warm, moist air rolling off of the Gulf of Mexico, dry air coming from the Mojave Desert, and cool air flowing off of the Rockies.  The combination of these air masses provide a lot of atmospheric instability, prompting thunderstorms.\n\nDue to the winds around Texas/Oklahoma, the storms are more likely to be supercells, and more likely to form tornadoes.\n\nTexas might have the most number of tornadoes in a given year, but Oklahoma actually has the most tornadoes per unit area in the US because of the wind patterns being even better for tornado formation there.
198999
I don't think tornados have a preference. It seems they like either one, especially if there's a trailer park! Seriously though, they can happen anywhere when cold air meets warm air. That's all I know about how they're formed. \nBut, from watching the weather reports about tornadoes in "Tornado Alley", I've noticed it doesn't matter if areas are incorporated or unincorporated. However, if it is unincorporated, there's definitely a lot less damage to structures (buildings). But even in an unincorporated area, buildings can be smashed.
222466
Dave in NC answered it perfectly.  Ill just add, if you are asking why tornados form over land- The rapid increase in heat needed to cause formation of tornados generally occurs only over land, since water modulates changes in heat.  However, sometimes they do form, but they are called waterspouts, and usually occur near hurricanes.
397369
http://www.bookfinder4u.com/search/Tornado.html\n\n\nyou should find it there..
365692
The US averages around 900 tornadoes per year.\n\nSome years it is much higher. Increased hurricane activity sometimes causes a rise in tornadoes reported. So particularly active hurricane seasons will cause there to be more than normal.\n\n:)
381488
There are three reasons why North America has so many powerful tornados.\n\n1. Cold dry air from the North.\n2. Warm moist air from the gulf of Mexico\n3. The Great Plains.\n\nWhen cold dry air from the north collides with warm moist air from the Gulf of Mexico, the moisture in the warm air condenses forming clouds. When this occures in a way that warm air gets trapped below the cloud cover, and cold air gets trapped above, it creates very unstable conditions.\n\nThe warm air wants to rise and the cold air wants to fall. The result is often a large thunderstorm known as a supercell. \n\nWhen this occures over the central portion of North America, known as the Great Plains, the flat landscape allows for the easy formation of horizontal columns of circular wind. One theory on tornado formation asserts that tornados form when these circulating columns get caught in an updraft (rising warm air).\n\nWhile tornados can form just about anywhere, even in mountainous regions, the Great Plains of North America provides ideal conditions.
745942
Excellent question!!  And one which is never fully explained on any weather forecast/ weather station....\n\nWeather conditions are controlled by the air currents over the Pacific Ocean, for the most part, first of all.  You can watch typhoons or Pacific hurricanes travel westward, until they reach a landmass, then these low-pressure storms will turn North-Northeast and follow the jet stream, until they are turned South-southeast ward, and affect the U.S. northwest states, Washington, Oregon, California.....\n \nThese extra-tropical storms keep their strength as they travel around the path of the Northern jetstream, droping rain and producing winds not unlike a hurricane, as they follow the jetstream paths around the world.  \n\nAfter these storms, these Pineapple Expresses, have traversed the United States, they again gain strength over the Northern Atlantic ocean, and then let go of the precipatation over Britian and Europe, where the Original storm dies.....\n\nAgain, excellent question.  Hope this enlightens you!!
799084
I reside in Dallas, Texas and you just never know. For instance today it is going to be a high of 88 degrees..tomorrow 74 and Sat only 66 and windy. Its normally mild here and sometimes windy..but we do have nice warm sunshiny days. I would prepare for chilly weather but not Artic or freezing...
628631
It depends on when you want to chase them.  If you're chasing in the winter, go to the Dixie Alley or areas near the Gulf of Mexico.  If you're chasing in the Spring, go to tornado alley, which includes Oklahoma, Kansas, and Texas.  If you're chasing in the summer, go to Michigan, Ohio, New York, Pennslyvania, and Southern Ontario.  Southern Ontario is in Canada, but they do see a lot of tornadoes and severe storms during the summer.  Also Manitoba, Saskatchewan, and Alberta are also good.  They have less storms, but more random and possibly more Oklahoma style tornadoes.
343523
Tornadoes have been reported in many other countries.  The U.S. just gets more of them than anywhere else; as already mentioned, formation conditions are the most favorable in the world in Tornado Alley.\n\nFor instance, Australia is another country that's believed to be a (distant) second in tornado activity; however, what tornadoes do form are probably underreported because of the sparse population.
928319
I've never heard it been used in weather but some most-known related slang terms to tornadoes are: twister ,whirlwind ,wedge , funnel , gustnado, landspout, willy-willy , or rope.\n\nI hope thats enough.
1128213
A tornado is not just wind, the fact that you can see them is either a if it drags condensation down witth them when they form (condensation funnel), or stir up dust and debris when they contact the ground. These "clouds" are actually rapidly spinning vortices (if you dont know it, look it up), that can produce winds in excess of 300 mph on the Fujita Scale (Ditto), and the stuff they can pick up and carry with them..... well, I think that about covers it.
92110
Tornadoes are formed by the clashing of drasticlaly different masses of air known as fronts.  A high pressure front meets with a low pressure front and the difference in their temperatures and pressures creates a strong wind that can form into the funnel clouds known as tornadoes.  This is not to say that all colliding fronts will yield tornadoes, but there are certain elements that can increase the likeliness of a tornado forming.  The swath of the mid-west United States from N. Texas / Oklahoma through Kansas / Nebraska and into Iowa / Missouri is known as "Tornado Alley" because there are more tornados per year in this area than anywhere else in the world.
13162
Actually, scientists understand a lot about tornadoes, but cannot completely predict them because they happen on such a micro-scale compared to other weather phenomenae.  Scientists can predict when conditions are favorable for tornadic activity (like when a tornado warning is issued), but can't predict excatly where one will occur until moments before hand.
290423
It is commonly thought that in a basement, you should seek shelter in the southwest corner. However, the best place to be would likely be in the corner that is in the direction that the tornado is coming from. This way, if the tornado hits your house, its winds will push the debris away from you towards the other end of the basement, leaving you unharmed.