PHILADELPHIA - JANUARY 27: Margaret White, of Philadelphia, Pennsylvania shovels snow from her driveway January 27, 2011 in Philadelphia, Pennsylvania. The Philadelphia region was covered in almost 17 inches of snow, closing schools in the city and suburbs. (Photo by William Thomas Cain/Getty Images)
As you all know by now, the overwhelming number of forecasters predicted a rather mild winter over the eastern half of the country. The key was a rather strong La Nina-very cold water in the tropical Pacific. Historically, time after time, that has led to winters with less snow than average-sometimes a LOT less than average. And, in all similar years, we NEVER got a snowstorm with more than seven inches in Philadelphia. In the Southeast U.S., the results are even more dramatic: strong La Nina’s lead to very warm and snowless winters. Not any more!!!!!!!
So, who got the winter forecast right this year? Yes, I know it’s just the beginning of February, but it is already a “bust” for the whole Eastern U.S. Lo and behold, one of the three forecasts I heard before the winter started that look accurate was from the Old Farmer’s Almanac. This is hard for me to write (not a fan), but they predicted “cold and snowy” not only for our area, but also for the Deep South, which has been blasted by wintry weather for the past two months.
I researched the OFA for a major project while at Penn State, going back over decades worth of forecasts, and found that they did WORSE than just flipping a coin. So, is this a case of a broken clock being right twice a day, or are they on to something? They claim amazing accuracy rates, but never show anyone how they calculate them.
Another impressively cold and snowy forecast came from a British astrophysicist named Piers Corbyn, who has gotten a good deal of publicity in some circles for his predictions of extreme cold and snow over the past two winters in Europe and the U.S. He is extremely political, and has not published his methods, so no other scientists can critique them properly. But results are results. What are the odds of someone making such amazing forecasts (“the coldest December for 100 years” in England-it was even colder than that!) two extreme winters in a row? He has made extreme forecasts that have not turned out (in 2007 and 2008, for example), but also had his wind predictions evaluated in a published study. They concluded: “the system performs better than chance”.
The third cold and snowy winter forecast came from Dr. Judah Cohen, from a company called AER (Atmospheric and Environmental Research), which provides seasonal forecasts for governments and industries around the world. We get to see Dr. Cohen’s forecasts regularly, since his is the company that provides us with the “eCast”, which is very helpful in forecasting up to 10 days ahead. He said the winter would be a cold and snowy one for just about the whole Eastern U.S.
So, how did these people do it? What are their methods, and can we learn anything from them? As a scientist who tries to be objective, I have been looking into their methods. I’ll give you my conclusions in the next blog.