h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

There is scarcely a place on Earth that a tornado of some form or another cannot form. If the right conditions prevail, a moisture-laden low overlaid with the straight line winds of a high pressure cell can bring them to life in a matter of minutes. And that is the most insidious thing about tornadoes. You have seconds, not hours, to react.

Luckily, the right conditions are generally limited to known periods of meteorological activity. If it's hot and humid, conditions are good.

Your first indication is generally the formation of a thunderstorm. There's an eerie stillness as the pressure is sucked away. The air is still and calm. No birds, no insect sounds. Cumulo-nimbus clouds build into towers, called supercells, and the normal afternoon thundershower begins to take on incredible energy. Lightning, dark green roiling skies, and continuous thunder are the precursors to the worst. When you watch the horizon, little letter "J" wisps begin to descend earthward.

When the first one connects with the ground, the heat feeds the vortex, and the tornado is born, marching or racing with the windspeed of the supercell that spawns it. Driving rain begins, and the roar at ground zero is deafening.

Depending on the category, windspeeds may exceed 150 miles an hour. At 150 miles an hour, a broomstraw will penetrate a 2x4 without breaking. It's not unusual to find pine needles driven a half inch into a cinder block foundation wall.

The safest place is underground. If it sticks up, a tornado will cut it off. Tree, house, bridge, underpass, person, car, truck, no matter. No joking here, either. The path is always well defined, and everything is gone. Some are ten feet wide, the worst known had a path of destruction over a mile and a half wide. And NO above ground structure ever made has been known to survive a direct hit.

Failing an underground structure, find an open ditch, or a culvert. If you are at home, get in the innermost closet or bath, preferably without windows. Pull over you every mattress, cloak or padding you can find in fifteen seconds. It's better if everyone is together.

The only up side is that they usually pass quickly.

Accurate, except for the fact that tornadoes(I was always taught) can only form in the midwestern US, and a scarce few other places on the planet... has something to do with being in-between two major mountain ranges, with cold Arctic winds meeting warm Gulf of Mexico winds in a bad spot.

Marc

As someone living in the Midwest I can vouch from personal experience that a tornado has a sound very similar to either a train, or a low-flying jet. This year in my area there were two touchdowns, one occuring at night. The night-time tornado was the scarier of the two because it could be heard but not seen.

As the original author states a basement, a bathtub, or an interior closet are all decent protection. Cover yourself with a sleeping bag, couch cushions, blankets -- whatever is available to shield you from flying debris. GET AWAY FROM WINDOWS.

You may only have seconds so it's a good idea to keep an eye and ear on reliable local weather during stormy weather. Keep a battery-powered radio handy in case you lose power.

One other point -- tornadoes move rapidly. Although they are fascinating to watch don't waste precious seconds gawking at a funnel when you should be trying to reach shelter as quickly as possible.

If you are in a car do not try to outrun a tornado. Find a ditch, a culvert, or an underpass -- get out of your car.

Although video of tornadoes can get lots of exposure in the media, dying for a story is not something that crosses the mind of most amateur videographers -- protect yourself first.



-THDoM

We've just had a tornado in Bognor Regis, England UK.


Our worst weather in 13 years....

Maybe so, but I thought that you get one or two each year down there on the S coast of Sussex.

While most common in the plains states of the U.S., tornadoes regularly terrorize the Deep South, the Northeast, and even the very tip of Florida.

Much of the damage done by Hurricane Andrew and Hurricane Georges was caused by perimeter tornadoes triggered by the storms. Along the Atlantic coast, hurricanes regularly trigger them as well.

Less common, perhaps, but equally as destructive as the plains storms.

Actually tornadoes can occur anywhere cool dry air moves into a warm humid mass of air.

Tornadoes have been reported on every continent except Antarctica.

On the otherhand the Midwest is a part of "Tornado Alley." In my area at the very end of Tornado Alley we get usually get five or six watches per year, and one to two warnings per year with a touchdown every several years. Watches mean that conditions are favorable for the formation of tornadoes. Even warnings do not necessarily mean a damaging tornado. Deep in Tornado Alley, including the south-central U.S. -- the panhandle of Texas, Kansas, Arkansas, Nebraska, and Oklahoma -- warnings and touchdowns are much more frequent.

In addition the conditions to produce tornadoes change, shifting southward during the colder months and moving back northwards during warmer months.

The deep South sees most of its tornadoes from October through March. The northern states see most of our tornadoes from April through September.

But we've had tornado watches and warnings every month of the year.

As for warnings, warnings are issued in several ways.

First the National Weather Service may spot an area on regular or Doppler radar that has a "hook echo" characteristic of tight circulation embedded within a thunderstorm. They will then issue a warning for areas in the path of this hook echo. This method can produce warning times of up to half an hour. The fun part is that the existance of a hook echo does not always mean that there is either a funnel cloud (a tornado in the air that has not yet touched down) or an actual tornado present in the storm ...

The second method is more certain but does not give as much warning: weather spotters in coordination with local law enforcement may report tornadoes or funnel clouds they have sighted. Then the warning sirens are sounded (They sound like air raid sirens.) This method does not give long warning times, maybe five minutes?

I have called in three funnel clouds but have yet to actually see a tornado on the ground. One funnel cloud actually passed directly over me, it was beautiful, long and sinuous, silver colored, and very large. The scale is not captured by television cameras.

I am very glad it passed over me without touching down, by the way.

In any case, we now have warning times of up to twenty minutes due to better radars. With the old method of reporting tornadoes we were lucky to have two minutes of warning. Fewer people die today because of improved warning times.

You really have not lived until the skies are dark and greenish, the rain and your neighbor's lawn furniture blow sideways past your front window, and you hear those sirens ...



Peace everyone,

-THDoM

Thanks for the correction... I wonder where it was I heard that we were the only unlucky ones...? =)

Heh, I'll always remember the massive tornado that destroyed the place I went to gradeschool at a few years back... saw it from my basement window touch down a little less than a mile away... freaky stuff. Totally demolished an entire school building and several homes, and there was not even one major injury... lucky!

Then we were all so excited, because CNN came to our little podunk town to talk about it. Anyone remember a story about the tornado that killed Cantrall? No? Yeah, I thought so...

Marc

We Midwesterners hafta stick together.

Southern England just had two tornadoes last week with the horrible storms that swept through Europe.

We just happen to have a few geographical quirks that do odd things to our atmosphere and make fun things like tornadoes more common. On the bright side we do not normally face earthquakes. We cannot neglect to mention New Madrid, Missouri in 1811 - 1812, the largest quakes ever recorded in North America ... http://asms.k12.ar.us/armem/richards/index.htm

Tsunamis seldom sweep through Ohio.

Nebraska is not known for its volcanoes.

Iowa has a very mild hurricane season.

A friend of mine in Australia after she saw the movie "Twister" assumed we all live in concrete bunkers. It took some serious reassuring before I finally convinced her that tornadoes do not chase us through the Midwest, nor do we have to rebuild our homes every two to three years ...



-THDoM

Volcanoes! We should have something in here about how to survive an unexpected volcano eruption, say, in one's backyard. Personally I like the "wet myself and pray" approach. At least that seems to be the most likely way to survive. Not that I have any experience in this matter...

Marc

I think probably the best thing one can do when faced with a growing volcano is ...

Move.

Get out.

Find a new home.

Abandon the old place.

Of course, one would do this AFTER cashing in the insurance policy ...



-THDoM