# Tag Info

24

Tornadoes are the result of small-scale effects such as the convergence of updraft/downdraft regions in a single thunderstorm, the stretching or entrainment of vertical vorticity, wind shear profiles, and even friction with the ground. Hurricanes rely on massive amounts of latent heat release from an atmosphere moistened by warm ocean waters causing rising ...

17

There are two factors at work here: Actual occurrence of tornadoes, Reports of tornadoes. Tornadoes are primarily associated with supercell thunderstorms, though they can also be associated with landfalling tropical cyclones, squall lines and bow echoes. Thunderstorms are favored in the afternoon to early evening hours as this is when integrated solar ...

17

The kind of tornadoes "tornado alley" refers to are associated with supercell thunderstorms. To first figure out why this region exists, we need to explore why this is a hotspot for supercells. Thunderstorms require energy and this energy comes in the form of convective available potential energy (CAPE). This is simply the vertically integrated buoyancy ...

15

Yes, if one takes the common meaning of the term "eye of the storm" to be the area of relatively low wind speed near the center of the vortex, most tornadoes can be said to have eyes. Cyclostrophic balance describes a steady-state, inviscid flow with neglected Coriolis force: $$\dfrac{v^2}{r} = -\dfrac{1}{\rho}\dfrac{\partial p}{\partial n}$$ where ...

12

It is especially rare to see a tornado destroying a series of skyscrapers. Yes, it's rare, but not for the reasons you think. The reason that tornados striking downtown areas is rare is that cities are but a tiny fraction of the land area in places where tornados most often occur, and downtown areas are but a tiny fraction of the land area in those cities. ...

11

You know, there hasn't been too much research into this... but there has been some. For the most part, it's been proven that a green sky most likely means that a thunderstorm is coming. According to a researcher: Green is significant, but not proof that a tornado is on the way. A green cloud “will only occur if the cloud is very deep, which generally ...

10

In addition to @casey's answer regarding the conditions (which undoubtedly is the main answer), don't forget the issues of size and sampling. In the US, the tornadoes can be large and destructive. Therefore US authorities and citizens are very interested in tracking and reporting them. You also have good communication. In other words you get much higher ...

9

Both the Fujita (F) and Enhanced Fujita (EF) scales measure damage and then use damage as a proxy for wind speed. Wind speed at the low levels is not directly measured unless the tornado is either very close to a doppler radar site or there happens to be a mobile radar sampling it. This provides very few tornadoes with directly sampled wind speed and is ...

7

It starts by identifying days with good overlay of shear and surface-based instability. In the US we have the Storm Prediction Center that helps indicate such days looking at models. Generally the very earliest signs that get chaser's attention are a reasonable trough moving into regions with adequate moisture and warmth (sometimes a cut-off upper-level ...

6

Summarizing the comments I made above in this question and in this one - Does this weather pattern have a name ? I believe significant parts of the US are experiencing a Stationary Front for the past one month. There has been plenty of media coverage of this event and if you google the term "stationary front" under news one will receive a lot of links to ...

5

Basically the de facto best operational source would probably be the Storm Prediction Center website. They provide this table: It caps out at EF5. However it also true to note that the scale was developed to mirror the Beaufort Scale into a range between the Hurricane Force on the Beaufort Scale and Mach 1. And as such, indeed in Fujita's 1971 ...

4

It depends. Take a look at this recorded presentation from the 27th Conference on Severe Local Storms by David C. Lewellen and the accompanying pre-print. This talk focuses on the effect of buildings on tornadoes though the buildings are examined as fixed blocks they are not modified or damaged, but remain a fixed obstacle to the tornado (he toward the end ...

3

Although there is a superficial resemblance between tornados and dust devils, they are very different. There is no connection between the two. I have seen lots of dust devils in reality, but tornados only in videos. Whereas tornados are very large and usually very wet, dust devils are very small and very dry. They occur in deserts and very hot, dry ...

3

No. The highest is the EF5. See https://en.wikipedia.org/wiki/Enhanced_Fujita_scale

3

Brian Dunning already went into this extensively in episode 4170 of Skeptoid: It's Raining Frogs and Fish In 1901, a rainstorm in Minneapolis, MN produced frogs to a depth of several inches, so that travel was said to be impossible. Fish famously fell from the sky in Singapore in 1861, and again over a century later in Ipswich, Australia in 1989. ...

3

I think you need some statistics to bolster your argument. It could be that there aren't so many big cities in America's 'tornado alloy', so the footprint of a super-cell storm has a low probability of crossing tall buildings. Check out tornado alley on Google Earth. There are still unanswered questions, such as why some supercell's develop tornados, whilst ...

3

They form due to strong convective forces, coriolis effects, local wind and weather, and local topography. The fire effectively creates an intense localized low pressure cell due to the heating of the air which can behave similar to any low pressure system. I haven't seen one on flat terrain like your picture shows but when performing slash burns for ...

2

Tornado alley exists because warm moist air from the Gulf of Mexico collides with cool dry air from over the Rocky mountains, this causes instability in the atmosphere. These two ingredients meet directly over the Midwest and plains. This results in rotation and then the rest is... Well, for those of us living in tornado alley, we hear tornado sirens far to ...

2

No, the mountains would still need to be west of tornado alley. It all starts with temperatures. You often hear the colloquial "warm\cold airmass battle" image. But more specifically, the vital requirement for tornadoes is warm air advection. Why? Because warm advection fundamentally means the proper wind shear (cyclonic turning with height) for sustained ...

2

Changing air currents is very difficult and energy intensive. You'd need to alter an entire weather system - no easy feat. If you heated a very large region of cool air you might prevent the spiraling that causes tornadoes to form, but you'd need to warm at least few states worth of upper atmosphere. It would be an enormous undertaking. There's also ...

2

The characteristic funnel of a tornado is caused by condensed water. A tornado is a swirling mass of air with very high vertical vorticity and a corresponding drop in pressure. Large tornados can have pressure deficits on the order of 100 hPa, which is significant compared to synoptic horizontal pressure gradients. The drop in pressure causes air to ...

2

I'll attempt some answer, but must admit it's a bit speculative. I think, like with many unusual/rare phenomena, there's a fair bit of observational bias and of psychology involved as well. Mechanism I remember reading about this in at least two popular meteorological publications, one book about extreme and strange weather and an article in (I think) in "...

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I'd have to say a tornado would be more dangerous than a straight wind of equal speed. Tornados have a very low-pressure center and violent updrafts as can be seen in this YouTube video . As the roofs are blown off you'll notice they get blown upward as well as sideways.

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Have you perhaps contact the National Weather Service or FEMA about that ? If not, then maybe find out from real estate that they might have data for each houses in your state. They may have the data or not, but it is hard to know. All I know is that each state has different types of soils that can or can't built storm shelter. I heard in Texas almost 1/2 of ...

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This may/may not actually answer your question "Do warnings verify better" because of the qualitative word "better" and other factors that play a role, such as terrain and forecasting office. Another factor to consider is the nature of the warning and size of the phenomenon. A radar, for example, may not be the best tool to show verification of a hurricane, ...

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Dr. Fujita constructed a scale connecting Beaufort Force, Fujita Scale, and Mach number which shows that the Fujita Scale theoretically goes to 12 (F12). As fortunate (and as horrible) as it would be to successfully ride out an EF5, imagine if you will surviving a tornado packing Mach 1 winds! !?!

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The shape of a tornado is due to the movement of air and not dust. The shape of a tornado is called a vortex. A vortex can occur in any fluid (air or liquid) where the fluid rotates about an axis line. Vortices are examples of turbulent fluid flow (air or liquid). When vortices occur in liquids they are sometimes called whirlpools. Tornados are high energy ...

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