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Believe it or not, at one time people thought that weather occurred in only one place and simply stayed put. (Benjamin Franklin first suspected this was untrue when he learned that a storm he experienced in Philadelphia was followed by a suspiciously similar one in Boston the next night.) In those days, predictions were based on the observations of courageous balloonists who went aloft in search of approaching storms. More often than not, these airborne oracles almost passed out from lack of oxygen.

Did You Know?

�������� information sharing is taking place on a global level. For instance, forecasts incorporate data gathered by U.S. satellites, which are shared with the entire world—even during times of crisis.

Today, the uses a powerful computer system to prognosticate weather patterns. The computer system combines data from radar, satellite images, computer models, high-tech weather balloons and hourly observations from virtually every airport in the country, as well as measurements taken by commercial jets as they fly about. Forecasters use this data system to predict future weather fronts. “The output of those computers is the basis of every forecast in the United States,” says Stephen Corfidi, a lead forecaster with the in Norman, Oklahoma. That data combined with old-fashioned human ingenuity (and, as you'll see, occasional gut instinct) is required to analyze the data and make predictions for hurricanes, blizzards, flash floods and tornadoes.

Just how reliable are experts' prognostications? The truth of the matter is today's forecasts—while more accurate than ever—can dazzle us with dead-on precision one day and be completely off the mark the next. Despite our mind-boggling advancements in storm prediction, colossal blunders still occur.

Reports From the Neighborhood

Do you like to watch the weather? The U.S. National �������� Service uses both “storm sitters” who report severe weather via ham radios or cell phones, and “cooperative observers” who dutifully record the weather every day, and mail in their observations at regular intervals. (Some folks have been mailing it in for over 50 years!) To learn more about the U.S. National �������� Service “storm spotter” program, visit .