CNN news 2012-04-07 加文本

cnn news 2012-04-07

CARL AZUZ, HOST: Hi, I`m Carl Azuz.

You`re watching cnn STUDENT NEWS.

We have a couple of awesome things on this particular Friday.

The Mansfield High Tigers in Texas got our social media question right, so congrats to them.

And we have a surprise for you in today`s good-bye. You`re going to love it.

First up, though, we are talking about hurricanes, because that is what forecasters at Colorado State University are talking about. Every year, they make predictions about the Atlantic hurricane season. It starts on June 1st and lasts through the end of November, although storms can form outside that season, as well.

This year, the Colorado State forecasters say we`re in for a less active season. They`re predicting 10 named storms. They think only four of those will become hurricanes.

A couple of things to keep in mind here, though.

One, these forecasts aren`t perfect. Last year, Colorado State predicted 16 named storms. We had 19.

Two, even if just one storm makes landfall, it can still cause serious consequences. Forecasters say it`s important to prepare the same for every hurricane season.

Turning to another type of severe weather now, tornadoes. Most of them only last a few minutes, but they can have a very serious impact, like the ones we reported on that hit Texas earlier this week. The National Weather Service says these twisters might have rated up to EF3 on the Enhanced Fujita Scale.

What does that mean in terms of the damage that a tornado can cause?

Well, that`s one of the things that Chad Myers explains in this breakdown.

CHAD MYERS, AMS METEOROLOGIST: Technically, a tornado is just a violent rotating column of air coming out of the bottom of a thunderstorm. But it takes a lot to get that violently rotating column to come out.

All you need for a tornado really to form, though, are thunderstorms and a jet stream. That jet stream is aloft. It makes the energy. If you have moisture at the surface, dry air, cold air pushing that moisture up, you can get a tornado to form in any state.

Those days where all the ingredients combine -- you get the humidity, the get the dry air, you get the jet stream, you get upper energy in the jet stream, you get winds turning as you go aloft. The higher you go, the winds actually change direction. That can cause storms -- those things all cause storms to exist and get big. Those are the ingredients that cause a big tornado day.

So now the EF scale, the Enhanced Fujita Scale, starts at 0 and goes to 5. Anything above 200 miles per hour is considered an EF5 tornado.

If you have a 0, you`re going to lose shingles.

A 1, you may lose a couple of boards on the roof.

A 2, you lose all the windows and maybe even a wall.

A 3, EF3, you will lose a couple of walls on the outside, but there will still be a part of the home standing.

An EF4, most of the home is gone, but you`ll still see the refrigerator, you`ll still see a closet and you`ll still see the bathroom.

An EF5, you cannot find the house. It`s completely gone.

We don`t know how big that Fujita Scale will be, how big that tornado will be, literally, until after we look at the damage.

We have this, this -- almost this triangulation that no other country in the world, no other region in the world, has. We have the Rocky Mountains to our west. We have the Gulf of Mexico in our south. We have Canada and very cold air masses coming down from the north.

All of those things combined make Tornado Alley, typically the Plains -- Texas, Oklahoma, Kansas, Nebraska, all the way to Chicago, as far south as the southeast, including Georgia and Alabama. That`s basically the new or the bigger Tornado Alley.

The greatest threat of a tornado is being hit by something that the tornado is moving. If you`re outside or if you`re not protected inside, if you get hit by a 140-mile-per-hour 2 x 4, you`re going to be killed. So you need to be inside on the lowest level, somewhere in the middle of the home, away from windows.

When you hear the word "warning" and you hear your county, that`s when you need to take cover. When you hear the word "watch," that means something might happen today. Let`s have a plan. When you hear the word "warning," it`s too late to make a plan. You need to already have the plan. "Warning" is the long word, it`s the bad one.