An example of a hook echo.
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NWSFO/Tuslas, OK

Tornado Forecasts

Tornadoes are hard to forecast. They don't last very long so there's not much time to figure out what's happening. Also, scientists don't really know how they form. They know what the weather's like when past tornadoes have formed, so that's what they use to make forecasts.

Meteorologists take measurements of the air called soundings. One of the things these measurements tells them is how stable the air is. Other measurements tell them the temperature and humidity. Using these measurements, meteorologists can tell if tornadoes are likely to form. When an area looks like it might get hit, they issue a tornado watch.

By using a new kind of weather radar, meteorologists can detect a tornado as it's forming--up to 20 minutes before it forms a funnel! Using conventional radar, they might have been able to see the tornado after it already formed. (A tornado would show up as a hook echo.) That doesn't leave much time to issue a tornado warning. Also, tornadoes don't always show up on radar. Tornado spotters are needed to give reliable observations of the weather. The more time people have before a tornado, the fewer people will be hurt or killed because they'll have more time to seek shelter.

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