Q: I see the long-range forecast is out from the “Farmer’s Almanac” and it predicts a very cold winter for most of the country. How accurate is long-range forecasting?
A: It depends on exactly what you mean by “long range,” says Brent McRoberts of Texas A&M University. “On forecasts within the next 24 hours, forecasts are usually very accurate,” he says. “Forecasts made between 1-3 days are usually pretty good. But beyond seven days or so, the accuracy rate tends to slip because factors that make up a forecast tend to change. So the shorter the time period, the more accurate the forecast. It’s interesting to note that ‘The Old Farmer’s Almanac,’ now in its 222ndyear and one of the oldest publications in the country, makes up its weather forecasts about a year in advance, and it claims to have an 80 percent accuracy rate. It uses a ‘secret’ method of weather forecasting that it’s used for over 200 years.”
Q: So long-range forecasts are nothing new, correct?
A: Weather forecasting has been around longer than you might think, says McRoberts. “The U.S. government started weather forecasting in the 1870s when Congress established a National Weather Service,” explains McRoberts. “It was aimed primarily for military uses. The National Oceanic and Atmospheric Administration (NOAA) was established in 1970 and has under it a number of agencies, among them the National Weather Service. But the goal was still the same – trying to give an accurate prediction of weather forecasting. Weather forecasting is done to predict long ranges, such as a year or more, or sometimes a season, such as summer, or the kind we are most familiar with, the four- or five-day forecast. Meteorologists use various charts based on air currents, fronts, satellite images and other data to make their forecasts.”
Weather Whys is a service of the Department of Atmospheric Sciences at Texas A&M University.