How come tornados can't form in the middle of a large city?

Answer 1

They can, a tornado can form anywhere where the weather conditions are right. A tornado begins in a severe thunderstorm called a supercell. A supercell can last longer than a regular thunderstorm. The same property that keeps the storm going also produces most tornadoes. The wind coming into the storm starts to swirl and forms a funnel. The air in the funnel spins faster and faster and creates a very low pressure area which sucks more air (and possibly objects) into it.

The severe thunderstorms which produce tornadoes form where cold dry polar air meets warm moist tropical air.

Answer 2

It's certainly possible for a tornado to HIT a large city. But as far as forming over one?

Well let's figure NYC. Highly unlikely that Midtown Manhattan would see a tornado spawned over Central Park. If you figure any large city, the "urban wind effect" creates stronger breezes between large buildings. That could very well prevent any tornado from forming, but it can't completely be ruled out.

In recent history though, tornadoes have HIT (not FORMED OVER) major cities like Oklahoma City and Nashville.

Answer 3

Most tornadoes follow a recognizable life cycle.[10] The cycle begins when a strong thunderstorm develops a rotating mesocyclone a few miles up in the atmosphere, becoming a supercell. As rainfall in the storm increases, it drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the rotating mesocyclone towards the ground with it.

As the mesocyclone approaches the ground, a visible condensation funnel appears to descend from the base of the storm, often from a rotating wall cloud. As the funnel descends, the RFD also reaches the ground, creating a gust front that can cause damage a good distance from the tornado. Usually, the funnel cloud begins causing damage on the ground (becoming a tornado) within minutes of the RFD reaching the ground.

Initially, the tornado has a good source of warm, moist inflow to power it, so it grows until it reaches the mature stage. During its mature stage, which can last anywhere from a few minutes to more than an hour, a tornado often causes the most damage, and can in rare instances be more than one mile across. Meanwhile, the RFD, now an area of cool surface winds, begins to wrap around the tornado, cutting off the inflow of warm air which feeds the tornado.

As the RFD completely wraps around and chokes off the tornado's air supply, the tornado begins to weaken, becoming thin and rope-like. This is the dissipating stage, and the tornado often fizzles within minutes. During the dissipating stage, the shape of the tornado becomes highly influenced by the direction of surface winds, and can be blown into fantastic patterns.

As the tornado enters the dissipating stage, its associated mesocyclone often weakens as well, as the rear flank downdraft cuts off the inflow powering it. In particularly intense supercells, tornadoes can develop cyclically. As the first mesocyclone and associated tornado dissipate, the storm's inflow is concentrated into a new area closer to the center of the storm. If a new mesocyclone develops, the cycle may start again, producing a new tornado. Occasionally, the old, or occluded mesocyclone, and the new mesocyclone produce a tornado at the same time.

Though this is a widely-accepted theory for how most tornadoes form, live, and die, it does not explain the formation of smaller tornadoes, such as landspouts, long-lived tornadoes, or tornadoes with multiple vortices. These each have different mechanisms which influence their development—however, most tornadoes follow a pattern similar to this one.[15]

Answer 4

lol

you're serious?

from the looks of the other answers, you've already pieced together that tornadoes CAN and DO form "over" large cities, even hit 'em once in awhile. I have just one thing to add ...

the reason you might think otherwise is that the U.S. concentrates its populations in cities such that there are lots and lots of wide open spaces surrounding large cities. Statistically speaking, the probability of a tornado forming over an open area is FAR greater than over a populated one, because there are simply more miles of open space than there are miles of congested city. If you believe in God then you can call the relative lack of direct hits on cities "merciful." If you don't believe it God then I guess you chalk it up to pure probability. But either way, you cannot say that it cannot happen. Well, I guess you can, but you'd be wrong.

Answer 5

They CAN form in the middle of a vig city, it will just be harder for them to survive because they need open land to roam around in. The buildings and what not in the city will choke the tornado to death as it will likely run into them more frequently.

Answer 6

They can, there has been one in my city and when I went on my VACA. to Kansas city on my way back i stopped and rested the night in a city that just had a tornado. So don't be going telling everyone they can't form in the middle of a city

Answer 7

what about the tornados that hit oklahoma city in 1999 and 2000? the '99 tornados hit them hard and did way major damage.

Answer 8

There was one in Salt Lake City a few years ago, I think in the late 90s.

Answer 9

Is this a serious question? I used to live in Oklahoma City and we got them. We got them in Florida and Alabama. They don't discriminate. When they say that tornadoes only hit trailer parks....it's a joke.

Answer 10

It forms above... and can plow through a large city anytime.