Forecasting Tornadoes
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When it comes to twisters, weather prediction has changed big time. Hi I'm Dave Thurlow and this is the Weather Notebook.

Until the 1950s, you would never see the word "tornado" in a weather forecast. Tornado watches and warnings were unheard of. Well that's changed. Today, Doppler radar spots the formation of some twisters more than 20 minutes before they cause any damage. And now the public can find out the tornado outlook on the Web. It's called the Storm Prediction Center or SPC.

Just like the usual weather forecast, the SPC tells you the chance of large hail, damaging winds, and even tornadoes. Where you're used to hearing about a 30 or 40 percent chance of rain, now you can go to the Web and learn if there's a 15 percent chance of tornadoes.

The new system works with a huge data base that includes all of the nation's severe weather reports over the past 20 years. With this help, forecasters can look at each day's pattern and estimate the risk of dangerous weather like hail, high wind, or tornadoes within 25 miles of any given spot. It separates out the risk for different kinds of severe weather. For instance, some days may be ripe for hail but not for tornadoes. Now you'll have a better idea of when to cover your head and when to duck for cover.

Thanks today go to writer Robert Henson. The Weather Notebook is a production of the Mount Washington Observatory. To find out more about forecasting tornados, log onto our website at weathernotebook.org.