by Gary Samson
Even Odds for The Old Farmer's AlmanacYou can't talk about forecasting in New Hampshire without mentioning The Old Farmer's Almanac, the 209-year-old publication from Dublin, best known for detailed, 14-months-in-advance weather predictions for the entire country. The folksy publication says its forecasts are based on "a secret formula devised by the founder of this Almanac in 1792, enhanced by the most modern scientific calculations based on solar activity and current meteorological data." This raises the eyebrows of professional forecasters, who are just starting to wrestle with the complex question of how fluctuating energy from the sun affects Earthbound weather, and who generally acknowledge that making specific predictions more than five days in advance is a fool's game. But you'd be hard pressed to hear a critical word about the wildly popular publication from meteorologists, especially in its home state. Most of them just ignore it. How good are the Almanac's forecasts, anyway? The publication claims an 80 percent accuracy rate, although it's not quite clear what this means. If the three-day prediction says "sunny" and it rains one afternoon out of the three, was the prediction accurate? If you were planning a picnic on the wet afternoon, you might think the Almanac blew it, but if your picnic was scheduled on one of the sunny days, you might give it a thumbs up. In an attempt to pin this down, several years ago the Telegraph of Nashua got the dean of the state's weather observers to judge a year's worth of three-day predictions. Andrew Rothovius of Milford, who has been keeping track of temperature and precipitation data for the National Weather Service since 1952, recorded day-by-day comparisons of the Almanac's predictions and his own observations. In the end, he gave the Almanac a roughly 50 percent accuracy rate, although he admitted that he had to make a lot of judgment calls.
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