[[caption-width-right:332:It can kill you. Still looks incredibly cool, though.]]
Tornadoes are quite possibly the most spectacular and destructive of all meteorological phenomena. Thus it is quite popular for them to show up in fiction. However, there are a great many misconceptions and myths surrounding them, not to mention numerous unrealistic portrayals in media (which is why DoNotTouchTheFunnelCloud is a trope), so we made this page to set down the facts about these astonishing and potentially deadly whims of weather.
* '''What is a tornado?'''
** A tornado is a rapidly rotating column of air that forms underneath a supercell thunderstorm. More specifically, to be considered a tornado, it must:
*** contact the ground
*** have a rotating wind speed of at least 65 mph
*** originate from a supercell thunderstorm
* '''How do tornadoes form?'''
** Speaking in the absolute most generality, a tornado is born of the horizontal rotation that begins when a cold, dry air mass slides underneath a warm, moist air mass. How this horizontal rotation becomes a vertical rotation, nobody knows for certain. No, seriously, ask any meteorologist and they will give you the same answer.
* '''What do they look like?'''
** It varies a lot really, but as for their shape, there are three common categories: [[http://farm6.static.flickr.com/5100/5429846368_b97410edea_o.jpg Rope]], [[http://holykaw.alltop.com/wp-content/uploads/2010/02/6538564-media_httpfarm4static_unFdg.jpg Stovepipe]], and [[http://www.sky-chaser.com/image/mwcl2013/m14tor14.jpg Wedge]]. A tornado will often change shape during its existence, and most will eventually end up as a rope tornado near the end (this is called "Roping Out"). Their color depends on two factors, the color of whatever the tornado picks up, and the direction it is viewed from. A tornado's funnel cloud is not always clearly visible either -- it can be blocked from sight by the rain falling from the associated thunderstorm ("rain-wrapped") or simply not dense enough to see easily. That's right. There is such a thing as an ''invisible tornado''.
* '''What do they sound like?'''
** Although it depends on a variety of factors, the most commonly associated sound is a low and steady rumbling sound, often compared to the noise of a passing freight train.
* '''Tornado Watch, Warning, Emergency'''
** '''Tornado Watch:''' A Tornado Watch is issued when conditions are ripe for a tornado to form.
*** '''Particularly Dangerous Situation (PDS) Tornado Watch''': Conditions that are capable of producing ''many'' tornadic storms (an outbreak) and/or supercells capable of producing very strong tornadoes (EF3 or above) are present.
** '''Tornado Warning:''' A Tornado Warning is issued either when there is considerable evidence that a tornado has formed (or is in the process of doing so) or when a tornado's presence has been visually confirmed.
** '''Tornado Emergency:''' A Tornado Emergency is an unofficial statement that is quickly rising in popularity. It is issued when a tornado has formed and is headed towards a populated area.
* '''What to look or listen for'''
** Strong and persistent rotation in the cloud base. If you see a [[http://en.wikipedia.org/wiki/Wall_cloud wall cloud]] and it is rotating, a tornado is imminent. Obviously, the existence of funnel cloud(s) themselves is ''always'' a warning of tornado conditions.
** A whirling cloud of dust and debris on the ground under said cloud base. May or may not be at the base of a funnel cloud.
** Hail or heavy rain followed by either a dead calm or sudden wind shift. '''BEWARE OF RAIN-WRAPPED TORNADOES.'''
** A loud, continuous roar or rumble (comparable to the sound of thunder or a passing train) that does not dissipate.
** Small, bright blue-green or white flashes at ground level.
** ''Persistent'' lowering of the cloud base, or a portion of it.
** A ''sudden'' power outage (e.g. the power was fine one minute, flickering and/or instantly out the next) if storms are around is also a possibly serious warning sign. If this happens in combination with ''any'' of the above, ''run'' for the best cover in your house, because it means the tornado is heading in your direction, if it's not already right on top of you.
* '''What to do'''
** '''NOTICE: FOLLOWING THESE INSTRUCTIONS WILL NOT COMPLETELY GUARANTEE YOUR SAFETY, HOWEVER DISREGARDING THEM WILL PRACTICALLY GUARANTEE YOUR DEATH! REMEMBER, THERE IS NO SAFE PLACE IN A TORNADO, ONLY LESS DANGEROUS ONES.'''
** In general, the first and best way of ensuring your survival is to prepare. The best ways to do this, well before any tornado watches or warnings are issued, are:
*** Designate a shelter area and equip it with what you need to survive. This should either be underground (ideally, such as a basement or storm cellar) or an interior room with no windows and no exterior walls. If you live in a mobile home know where your park's community shelter is, or where the nearest solid structure is.
*** Make a plan so that you are able to get to that shelter in a moment's notice.
*** For those who live in mobile homes and ''cannot'' evacuate quickly via vehicle or who fear a tornado that can't be escaped - a very good idea is to have an underground shelter built UNDER the mobile home with an entrance to the shelter through the floor of the mobile home or immediately outside one of the door.
*** You should also have digging tools (at least a strong shovel and thick work gloves) in your shelter space in case you need to dig yourself out, and a whistle or air horn or other loud alarm device to get attention for others to help you dig out. If you can't fit digging tools (you're in a bathtub under a mattress, for example) make sure to have that whistle or air horn in your space next to you, and in a way where you will not have to move to use it if you are trapped. While stocking tools in your emergency kit, you should also include a plumber's wrench (the most common tool used to shut off gas lines) and learn how to use it to turn off a potentially leaking gas line or a broken water supply flooding a basement.
*** GET A WEATHER RADIO WITH BATTERY BACKUP so you can be alerted to warnings even if you are sleeping or have the TV off or the power is out. If you have a smartphone, it also is a good idea to invest in a quality weather warning/storm conditions app. Newer smartphones on all the major carriers also have support for [[http://www.nws.noaa.gov/com/weatherreadynation/wea.html#.U74SBvnlpe0 Wireless Emergency Alerts]], which will alert you if you are in or drive into a warned area. But a weather radio in addition is never a bad idea; cell phones may not be able to provide service or alerts if critical infrastructure is damaged, the weather radio may be old technology but it's done the job well for decades.
** '''WHEN A WATCH IS ISSUED'''
*** If you do not have them on already and are able to get to them, put on a pair of thick-soled shoes when a tornado watch is issued and have a sturdy rain jacket within reach. In the aftermath of a tornado, you will need them. Having a motorcycle helmet with visor (or a bicycle helmet and goggles) nearby is also a good idea, as flying debris striking you in the head could prove to be fatal, and there's going to be a lot of sand/mud/grit/glass you do ''not'' want in your eyes.
*** Put dogs on leashes and small dogs or cats in carriers. Pet birds and small animals should be put in their cages. If there is room, carriers, cages, and leashed pets should be moved to the shelter area. If there is not room, they should be placed in the most interior room or the basement in general. As for horses and similar large animals there are two schools of thought: one says freeing them to allow to run to safety on instinct is best, the other says keeping them contained is better. As most barns and stables are flimsy structures, it's likely better to allow free running if particularly severe storms are possible or likely, and you can track/identify the horses or livestock.
*** Make sure your phone is charged (or on charger) and easy to grab fast. Make sure your wallet/purse is in reach - it probably should be kept on you.
*** If you live in a mobile home and have chosen to flee in a vehicle to stronger shelter/away from the storm, make sure the vehicle has a full or at least half full tank of gas, the tires are properly inflated, and it will start. In fact, if you can do it, the watch is probably the best time to go ahead and evacuate your mobile home for a sturdier building if you can stay at a friend's or family member's or similar.
*** If there is a watch and/or severe storms are around during sleeping hours, if it is at all possible, sleep in your shelter area (e.g. if you have a basement or underground shelter or safe room capable of sleeping in).
*** If you ''own'' a fixed structure or especially a space with an underground area capable of occupancy in an area with a lot of flimsy housing such as mobile homes, be a GoodSamaritan and open it/stay open during a tornado threat. Doing this will literally ''save lives'' if a tornado strikes.
** '''REMEMBER, JUST BECAUSE YOU DON'T SEE A TORNADO, DOESN'T MEAN IT ISN'T THERE. OFTEN, A TORNADO CAN BECOME RAIN-WRAPPED, MEANING THAT THE TORNADO BECOMES OBSCURED BY RAIN. ANOTHER THING THAT OFTEN HAPPENS IS THAT A TORNADO FORMS, BUT NO FUNNEL CLOUD IS VISIBLE.'''
** '''WHEN A TORNADO WARNING IS ISSUED OR YOU SEE TORNADO CONDITIONS'''
** '''IF YOU ARE AT HOME:'''
*** Head to an interior closet or bathroom on the lowest floor. If you have a basement, go there. Try to get under something sturdy like a table or a mattress. Do not go under an area where there is a heavy object like a piano or a refrigerator on the floor above, as these would be the places most likely to give way.
*** Stay as far away from any windows as possible. If they shatter, it will send shards flying everywhere.
*** When you get to your shelter, get on your knees, crouch down and cover your head, put on your motorcycle helmet and/or bike helmet and goggles, and cover your head [[http://www.spc.noaa.gov/faq/tornado/crouch.jpg like so.]]
*** '''IF YOU ARE IN A MOBILE HOME, ''GET OUT IMMEDIATELY!!!'' ''' Put on your helmet as you are doing so. Then, head to the nearest underground space or fixed structure and get inside, or head into the closest ditch if there isn't anything else nearby. If you have more lead time (20-30 minutes of warning) driving out of the storm's path is a better idea than a ditch. Mobile homes are '' '''VERY''' '' dangerous places to be in a tornado, and can be destroyed by even the smallest ones. Despite previous advice to the contrary, you even have a better chance of surviving ''driving away from the tornado in a vehicle'' or ''outside in a ditch'' than you do in a mobile home. [[PunctuatedForEmphasis GET. OUT.]] Unless, of course, you have an underground shelter built under or next to the mobile home, in which case get down into it.
** '''IF YOU ARE OUTDOORS:'''
*** If there is a fixed structure nearby, like a house or a gas station, head inside and get into an inside room. If you find yourself in a building that has a lot of open space (such as a supermarket or a bank), head for the sturdiest place you can, such as a walk-in freezer or a vault if at all possible.
*** If there is not a fixed structure nearby, or there is and you don't think you could get to it in time, try and find a low spot, like a ditch, dive into it, lie flat on your belly, and put your hands over your head.
** '''ON THE ROAD:'''
*** If the tornado is off in the distance, and there is not much traffic, try and vary your speed and angle and direction as to avoid it.
*** If the tornado is headed towards you (if it looks like it is steady and not moving, ''IT IS MOVING TOWARD YOU''), find an underground space or a fixed, solid structure and get inside as soon as possible. If there are no such options, pull over to the side of the road, and get into a ditch as far away from the road as possible. '''DO NOT''' seek shelter in an overpass and '''DO NOT''' try to outrun it unless you are experienced enough with weather and sure enough of your surroundings (and the tornado is moving slowly enough) that you are ''certain'' of escape.
*** If the tornado is headed towards you and you do not think you have time to do any of the above, buckle your seat belt (as it should be already), roll up your windows, put your head between your knees, put on any helmet and goggles you might have (from a motorcycle helmet to a hard hat), and leave the vehicle running so the air bags will activate if there is a collision. This should be your ''very last resort,'' because your odds of surviving with it are very, very low.
** '''After the Tornado:'''
*** '' '''REMAIN CALM!''' '' Freaking out will make things worse, and will get in the way of your ability to make decisions.
*** If you are trapped in debris, calculate your situation before you move. Are there downed power lines or open electrical wiring in your way or on you? If so, DO NOT MOVE. Will moving collapse the structure or debris further on you or on others? If the answer to that is no and you can get out of the debris under your own power, do so. Otherwise, scream, use your phone if it still works to call 911, make use of your air horn or whistle - make as much noise with as little movement as possible.
*** In the same way, be absolutely careful when lifting debris off of others. Yes, you may want to just get your little brother out NOW. But being aware of electric shock hazards and worse collapses will save both your lives.
*** If you are with family members or any other group, '''STAY TOGETHER''' and wait for emergency personnel.
*** ''' ''Watch your step!'' ''' After a tornado, there will be debris '''everywhere.''' You need to be aware of where you are putting your feet so you don't accidentally step on an exposed nail. This is why when watches are issued, you should wear thick work boots or combat boots.
*** ''' ''FOR THE LOVE OF GOD, STAY AWAY FROM DOWNED POWER LINES!!!'' ''' They don't flash and spark like in the movies.
*** ''' ''DO NOT LIGHT A MATCH OR A LIGHTER.'' ''' There will be a significant chance that the tornado caused a gas line to rupture. This is also why you need that plumber's wrench mentioned earlier in your emergency kit - if you see destroyed structures or smell gas, turning off the gas to them will prevent fires and explosions if firefighters haven't already arrived to do so.
*** Follow any instructions given to you by emergency personnel. It is their job to make sure that you stay alive, so following their orders is in your best interests.
*** If the medics say that you are OK, then go out and help. After a tornado, especially a big one, emergency services will be stretched to their limits, they will need all the help they can get.
*** Related to the above, if you have a vehicle that runs (even with broken windows or cosmetic damage), especially a truck or van or similar large vehicle, you can provide some of the most valuable help possible - transporting injured people to medical assistance, towing or pushing debris that blocks roads, and similar. Even a smaller car incapable of towing or carrying injured people/navigating roads full of debris can be helpful in a vital way - charging phones and tablets so people, especially in an area with power outages, can get information and warnings of other storms in the area. Similarly, if you have a generator that is fueled and works, inform emergency crews of this as well - any source of power is very much needed.
*** Stay out of heavily damaged houses, they could collapse at any time.
* '''WHAT NOT TO DO:'''
** '''AT HOME:'''
*** '''DO NOT LEAVE YOUR HOUSE!''' Unless you are in a mobile home OR the tornado is already wiping fixed structures from their foundations elsewhere, your best bet is to stay put. Leaving a fixed structure will only '''increase''' the chances of you getting killed in anything below an EF5. A storm capable of spawning a tornado will also be capable of producing rain in mass quantities, high winds, and hail. Flash floods are also possible.
*** '''DO NOT''' run around and try to open every door and window. It will rob you of valuable time you need to take shelter.
** '''ON THE ROAD:'''
*** '''DO NOT TRY AND HIDE UNDER AN OVERPASS. THIS WILL ''NOT'' PROTECT YOU FROM A TORNADO.''' The details will be explained below.
* ''' The Fujita Scale''' or '''F-Scale''' was developed by Dr. Ted Fujita as a way to equate certain amounts of damage with a tornado's wind speed. Implemented in 1971, it ranked tornadoes on a six point scale from 0 to 5. It was a good idea, but it had some major problems, such as its inability to take into account how different structures handle being struck by a tornado or that the evaluation of the damage itself was very subjective. On February 1, 2007, the F-Scale was replaced with the Enhanced Fujita Scale, but only in the United States for a period of time; Canada didn't switch over until April 1, 2013. Any tornado that was previously ranked using the Fujita Scale was not reevaluated post-switchover, so a tornado that was ranked as an F3 in 1997 (for instance) would remain an F3, regardless of whether or not its damage would have justified a higher, lower, or similar rating on the EF-Scale.
* ''' The Enhanced Fujita Scale''' or '''EF-Scale''' is the successor and improved version of the Fujita Scale. Unlike the F-Scale, the EF-Scale is much more specific about what sorts of damage results in where a tornado is ranked. It also takes into further account how different factors effect how much damage a structure suffers, such as the kind of structure, how it was built, how well it was built, effects of debris, etc. Like the F-Scale it was based on, the EF-Scale ranks tornadoes on a 6-point scale from 0 to 5. An [[http://www.srh.noaa.gov/images/mlb/surveys/012210/Viera_CraneCk1.jpg EF0]] has wind speeds ranging from 65 to 85 mph, an [[http://www.srh.noaa.gov/images/mlb/surveys/092007/pic1.jpg EF1]] ranges from 86 to 110 mph, an [[http://www.crh.noaa.gov/images/lsx/recent_event/06_08_2009/ef2damage_2.JPG EF2]] ranges from 111 to 135 mph, an [[http://www.crh.noaa.gov/images/ict/wxstory/2012/april14th/damage/sg/Oaklawn26.JPG EF3]] ranges from 136 to 165 mph, an [[http://upload.wikimedia.org/wikipedia/commons/2/2e/EF4_tornado_damage_example_2.jpg EF4]] ranges from 166 to 200 mph, and an [[http://edudemic.com/wp-content/uploads/2012/03/joplin-missouri.jpg EF5]] is any tornado with winds above 200 mph.
'''Other Terms and Terminology'''
* '''Supercell:''' The type of thunderstorm that most tornadoes spawn from. They contain a large rotating core called a mesocyclone.
* '''Cold-air funnel''' or '''gustnado''': Funnel clouds and tornadoes that are spawned from low-topped thunderstorms, "popcorn thunderstorms" in summer, or gust front/squall line storms that aren't specifically supercells. They often form and dissipate quickly, making them harder for radar to detect, but they are also often weaker (EF0 to 1 most of the time) than supercell mesocyclone tornadoes, and have shorter damage tracks. They (and landfalling waterspouts, which often form similarly) are the most common tornado west of the Rocky Mountains in the US, where supercell tornadoes are more rare.
* '''Tornado Family:''' Tornadoes that spawn from the same supercell are referred to as this.
* '''Tornado Outbreak:''' An event where a single storm system spawns multiple tornadoes.
* '''General Misconceptions'''
** '''The winds of a tornado are exclusively located within the funnel cloud. DoNotTouchTheFunnelCloud.'''
*** '''False:''' The funnel cloud is only the center of the tornado, the winds themselves extend ''well'' outside the funnel cloud, which is why it's not uncommon to see a debris cloud extending beyond the funnel cloud (case in point, the page image). The funnel cloud is simply the part of the tornado where the pressure drops low enough for water vapor to condense.
** '''The wind of a tornado are exclusively vertical.'''
*** '''False:''' See the definition of a tornado.
** '''Tornadoes destroy mostly by dropping the atmospheric pressure, causing houses to explode.'''
*** '''False:''' Tornadoes destroy mostly by their intense winds, along with picking up objects and turning them into projectiles to pummel other things (like your house). If you watch any footage of a tornado destroying something, you will notice that the structures tend to be blown ''away'' rather than blown ''up''.
** '''There are no tornadoes in _____.'''
*** '''FALSE.''' In the US alone, every single state has recorded a tornado at some point or another. While this is a half-truth in that ''generally,'' tornadoes, say, in California are rare and generally under [=EF2=] if that, they can and do happen there, and weaker tornadoes aren't nothing to ignore especially in areas unprepared for them, because said areas often have more glass in more places, weaker building codes for wind, and the like. An[=EF0=] or [=EF1=] that becomes a whirlwind of glass in a populated open area with no one sheltering can be as if not more deadly than an [=EF3=] with everyone in proper shelters or that only hits vacant areas.
** '''The sky turning an eerie shade of green is a telltale sign of a tornado.'''
*** '''Partially true:''' A green sky can be a sign of severe weather in general, not just a tornado.
** '''You can outrun a tornado in a vehicle.'''
*** '''BOTH TRUE AND FALSE.''' In some circumstances (e.g. if you can clearly see the tornado and track the direction in which it is moving), you not only ''can'' but ''should'' drive away from it. People have survived tornadoes doing this (and it's how storm chasers generally survive being near tornadoes). At the same time, there are situations where you ''cannot'' outrun a tornado in a vehicle, and in those situations, you are best getting off the road ''immediately'' into the strongest structure available. Of note is this storm chaser's opinion on the matter: http://126.96.36.199/~thecopyf/stormhorn.com/2010/11/14/leave-your-car-and-take-shelter-in-a-ditch-not-so-fast/
*** Other factors to consider when deciding when to run from a tornado include traffic conditions, the state of your car, and the state of local roads. If any of these could leave you stopped in the tornado's path, you'd be safer if you parked and got under shelter.
*** If you must leave your car to seek shelter, pull over to the side as far as possible to avoid impeding other drivers or emergency personnel. And needless to say, never venture onto unpaved roads or open fields to escape a tornado. Heavy rain can turn these into a bog in minutes, snaring your car AND making it more difficult for emergency vehicles to reach you if you need them.
** '''Overpasses provide safe shelter from a tornado.'''
*** '''[[PunctuatedForEmphasis FALSE! VERY! VERY! FALSE!]]: ''Never''''' seek shelter under an overpass during a tornado!
*** The winds of a tornado are horizontal, not vertical. They are not "sucking you up"; instead, they are coming at you very hard from the side. A surface above your head will do ''nothing'' to protect you from them. Additionally, the winds are ''rotating'', meaning that you will get hit from all four sides. An overpass might block, say, the south wind, but the north wind will be coming right at your face -- and because the winds can still get to you, the objects and debris they are carrying can too.
*** The instinctive 'safe zone' of an underpass -- the triangle where the sloping wall meets the roadbed -- is actually the most dangerous place to be. The winds will be stronger there, both because it is higher off the ground and because they are being funneled through a smaller space. Some overpasses have horizontal girders, but many do not; and even if your overpass does, the rotation of the winds will make it near-impossible for you to brace yourself.
*** Even if the tornado doesn't hit, parking under an overpass usually means stopping in a traffic lane, which is both ''illegal'' and ''dangerous'' to you and to others. Someone may plow right into you because they may not see you in time to stop. You could also trap people in the storm's path against their will. Even ''worse'', you could even prevent emergency response vehicles from getting to where they are needed, preventing them from saving lives.
*** '''Why does this myth persist?''' It most likely runs on two things: the fact that overpasses themselves survive tornadoes and the prevalent misconception that a tornado has vertical suction. It doesn't help that there is at least one highly-publicized case where a news crew successfully weathered a tornado under an overpass -- the [[http://en.wikipedia.org/wiki/April_26,_1991_tornado_outbreak#El_Dorado_Lake.2FKansas_Turnpike_Underpass.2C_Kansas 1991 El Dorado, Kansas tornado]] -- '''BUT''' this was something of an anomaly. Firstly, the tornado did not directly strike. Secondly, this particular overpass had heavy girders forming an odd, sheltered "box" under the roadway which blocked much of the horizontal force of the wind -- a feature distinctly ''lacking'' in most overpasses. Nevertheless, many others have decided that this "proves" that an overpass provides shelter from a tornado and paid the price; case in point, on May 3, 1999 three different overpasses took direct hits from tornadoes, two of these from [[http://en.wikipedia.org/wiki/1999_Bridge_Creek%E2%80%93Moore_tornado the legendary Bridge Creek-Moore, Oklahoma tornado]]. At least one ''fatality'' occurred at each overpass, and virtually everyone that managed to survive suffered moderate to life-threatening injury, including several lost limbs.
*** In short, an overpass is ''no'' substitute for being in a well-built structure, or better yet, being underground. If you absolutely, positively must shelter underneath one, get as low to the ground as you can and cover your head with your arms.
** '''If a tornado is about to strike your house, opening all the windows will reduce the damage.'''
*** '''False:''' This bit of folk wisdom depends on the myth that tornadoes 'explode' houses through the difference in atmospheric pressure. In reality, tornadoes destroy houses through rotating horizontal winds and airborne heavy objects (i.e. cars). Opening windows does nothing to prevent either of these and only wastes time you could be using to make ''yourself'' safe.
** '''The northeastern most corner of a house is the safest.'''
*** '''False:''' The rationale behind this one is the myth that tornadoes only move northeast, which we will get to later, but this one is false because it forgets that the ''winds'' of a tornado are circulating even when the tornado itself is moving in a straight line.
** '''The southwestern most corner of a house is the safest.'''
*** '''False:''' This one, which may be heard more often than the "northeastern most corner" version above, is based on the idea that debris will be blown ''away'' from the southwestern part of a house. Again, however, this ignores the circulation of a tornado's winds.
** '''No tornado sirens means no danger.'''
*** '''FALSE''': Some places (e.g. in the West and Northeast and South US outside of Tornado Alley, for example in Colorado or Montana or New York or North Carolina ''et cetera'') often do not have sirens or other outdoor warning systems, or immediately usable ones to be sounded for a weather threat. Even in places with sirens, winds and rain can drown out their effective range (as in, you can't hear the siren going off or can only faintly hear it), as can city noise in an urban area. Or sirens are run on main electric power, which means if the power goes out they do too. Or someone doesn't trigger them or they don't work for some reason or other. While any civil defense siren going off ''definitely'' means you should take shelter and check to see what is happening while you do (don't assume it's a test!), you should also not assume that sirens will warn you of tornadoes - again, get a weather radio, and if you have a smartphone, a weather warning/storm conditions app and/or enable emergency alerts, and if there is severe weather around, pay attention and keep an eye out, because sometimes, although less common than in the past, a dangerous storm can escape notice entirely until someone spots it.
** '''Tornado warnings happen all the time/the sirens go off every storm, there's no need to take shelter unless things look dangerous.'''
*** '''FALSE''': A tornado warning or siren activation is only issued under two circumstances: Doppler radar has determined a storm contains a rotating mesocyclone which may form a tornado at any minute (if it hasn't already done so) or someone has reported funnel clouds or a tornado touchdown. It isn't a watch, nor is it even a severe thunderstorm warning, which imply lesser hazards. If it's a tornado warning, there is reason to believe there is an actual tornado. Also, while warnings used to be issued for entire counties (which did make this misconception ''slightly'' true, in that most tornadoes aren't big enough to flatten an entire county so a tornado could "miss," say, the northern part of a county, which led people to be far more cavalier about warnings in tornado prone areas), this is no longer the case: warnings are targeted toward a tornado's actual path as of TheNewTens. Also, especially at night or in heavy rain/fog/hail conditions, sighting a tornado even at close range may be near impossible. (As an example, people thought the Tri-State Tornado was a fog bank). The ''only'' thing still even slightly true about the idea that tornado warnings can be ignored is that ''most'' tornadoes are relatively localized with fairly small in comparison damage zones (which is why tornado recovery is often faster than, say, hurricane or earthquake recovery, because resources aren't themselves destroyed within a 50-100 mile radius), that said, are the odds you won't get hit worth what happens if you ''do'' get hit unprepared and unsheltered? Especially when the worst thing that can happen from heeding the warnings and taking shelter being some inconvenience or wasted time (which ''dying in a tornado'' tends to be a lot more of)?
** '''Skipping Houses'''
*** '''True ''and'' False:''' Tornadoes have gotten a reputation for seemingly "skipping" over houses. Seemingly lifting off of the ground and then coming down again. However, they truly don't do that. At least, not in ''that way''.
*** A tornado's intensity can vary greatly during its lifespan. Sometimes a tornado will briefly weaken to where it won't do much damage and then quickly re-intensify and start doing damage again.
*** Some violent tornadoes can briefly split apart at the base into multiple vortices that will simply pass by one structure and hit the one next to it.
*** Some violent tornadoes can also cause a "satellite" tornado to form, which also have the same effect.
*** Tornadoes ''are'' capable of "skipping" in the sense that it will briefly lose contact with the ground. However, this tends to be more like skipping neighborhoods than skipping individual houses.
** '''Bigger = Stronger'''
*** '''False:''' While there is a trend for larger tornadoes to be stronger, that is not always the case.[[http://upload.wikimedia.org/wikipedia/commons/9/98/F5_tornado_Elie_Manitoba_2007.jpg This]] tornado that struck Elie, Manitoba was an F5 (Canada's first and only F5.)
** '''No funnel cloud = No tornado'''
*** '''False:''' Not all tornadoes have a visible funnel cloud.
** '''All tornadoes travel northeast'''
*** '''False:''' Many do, but not always. Belief in this is what likely got several storm chasers killed or injured (including the very experienced scientist chaser Tim Samaras, who was killed along with his son and his chase partner, and a crew from Creator/TheWeatherChannel that got injured) in the 2013 El Reno, Oklahoma tornado -- most of the chasers who came too close to the tornado seemed to be traveling under the assumption that the tornado was moving northeast. The circulation was simply too wide (with satellite tornadoes and variable wind directions) to have ''any'' safety margin in almost any direction -- distance and/or shelter, not direction, was the only safeguard.
*** The [[https://en.wikipedia.org/wiki/1997_Central_Texas_tornado_outbreak#F-5_Jarrell_tornado May 27, 1997 Jarrell, Texas tornado]] is infamous among those who study tornadoes for a multitude of reasons, namely the [[https://extremeplanet.me/2012/06/26/aerial-damage-from-the-f5-jarrell-tornado-the-most-intense-tornado-damage-ever-photographed/ absolutely devastating]] damage it caused (which was arguably made worse because the tornado itself was an unusually slow-moving one) coupled with the fact that the tornado went from a stationary rope tornado to a multi-vortex wedge tornado that abruptly started heading southwest and literally wiped an entire neighborhood off the face of the earth.
** '''[[TrailerParkTornadoMagnet Trailer Parks Attract Tornadoes]]'''
*** '''False:''' Tornadoes do not discriminate. This myth likely arises from the reality that tornado strikes on mobile homes (which are incapable of surviving even the weakest tornadoes) are dramatic enough to stick in common memory. Television news crews perpetuate the myth by filming at trailer parks, where the easily-damaged mobile homes provide ample shots of extreme devastation.
** '''Tornadoes cannot strike downtown areas.'''
*** '''False:''' [[http://en.wikipedia.org/wiki/List_of_tornadoes_striking_downtown_areas Yes, they absolutely can.]] It's rare since the odds of a tornado hitting any one particular area is a complete game of chance, but it is still possible. See the Costliest Tornado below, which was costly ''because'' it hit a downtown area.
** '''Tornadoes cannot cross rivers/hills/valleys/mountains.'''
*** '''False:''' Tornadoes are in no way hindered by the terrain. There are several cases of tornadoes crossing rivers, going over hills, crossing valleys, and even ''climbing mountains.'' Again, the terrain does nothing.
* '''Most Destructive Tornado'''
** This label is an infamous matter of opinion (especially on storm chaser forums) since one person's definition of "most destructive" varies from another's, especially when you take fatalities, damage to physical structures, speed, and so on into account, so [[RuleOfCautiousEditingJudgment in the interest of not starting a flame war]], we won't be giving our opinion on this page. That being said, those aforementioned variables (among others) ''do'' have records that aren't contested or disputed as of this writing, so they will be listed below.
* '''Largest Tornado Outbreak'''
** '''The Late April 2011 Outbreak''', April 25-28, 2011. This outbreak consisted of 127 [=EF0s=], 147 [=EF1s=], 50 [=EF2s=], 22 [=EF3s=], 11 [=EF4s=], and 4 [=EF5s=], for a grand total of 358 tornadoes. Tornadoes were reported from Texas all the way north through to Michigan, New York, and even into Ontario.
* '''Deadliest Tornado'''
*** '''The Tri-State Tornado''', March 18, 1925. 695 people were killed by this tornado.
*** '''The Daulatpur-Saturia, Bangladesh Tornado''', April 26, 1989. ~1,300 people were killed by this tornado.
* '''Costliest Tornado'''
** '''The Joplin, Missouri Tornado''', May 22, 2011. This tornado caused approximately $2.8 ''billion'' in damage.
* '''Longest Track and Duration'''
** '''The Tri-State Tornado''', March 18, 1925. This tornado traveled over 219 miles, started in Missouri before crossing the border into Illinois and then passing into Indiana. In all it cut through three states (hence the name) in a time span of 3 and a half hours.
** '''The El Reno, Oklahoma Tornado''', May 31, 2013. This tornado peaked at 2.6 miles wide.
* '''Fastest Forward Speed'''
** '''The Tri-State Tornado''', March 18, 1925. This tornado was not only long-lived but ''fast'' at 73 mph.
*** An honorable mention has to be given to the aforementioned 2013 El Reno tornado. While the tornado itself had a forward velocity of 55 mph, some of the subvortices traveling along its southern edge were clocked in excess of 100 mph.
* '''Fastest Wind Speed'''
** '''The Bridge Creek-Moore, Oklahoma Tornado''', May 3, 1999. Wind speeds of up to 318 mph were recorded by mobile Doppler radar units.
* '''Most Times Struck By Tornado'''
** '''Oklahoma City, Oklahoma, US'''. Counting the metro area ''and'' the suburbs such as Bridge Creek and Moore, the Oklahoma City region has been hit by at least five significant tornadoes.
** '''Xenia, Ohio, US''' holds the record out of Tornado Alley proper - it has been hit by two significant tornadoes.