September 2, 2010

2009-10 Snowfalls ‘Once In A Century’ Event

Record snowfalls that fell in parts of the U.S. and Europe in late 2009 and early 2010 were the result of a once-in-a-century collision of two weather systems, according to a new study recently published in the journal Geophysical Research Letters.

The study, also the subject of a September 1 article by BBC News reporter Pamela Rutherford, took a look at six decades worth of snowfall measurements and satellite data.

Ultimately, the researchers discovered that the record amounts of snow that blanketed the Mid-Atlantic States and parts of Northern Europe "were caused by an unusual combination of an El Nino event and the rare occurrence of a strongly negative North Atlantic Oscillation (NAO)," according to Rutherford.

"The NAO was probably as negative as it's ever been in the instrumental record, which goes back to the early 1800s. This was a once in a century type of event," lead author Richard Seager, a meteorologist with the Lamont Doherty Earth Observatory at Columbia University, told BBC News on Wednesday.

"The NAO on its own doesn't cause much precipitation in America. It just makes it cold. The El Nino makes the US wetter than normal so combined with the NAO it caused the precipitation in America to fall as snow," he added, noting that last year marked the first time that this specific combination of climatic events had occurred since the mid-1780s.

The 2011 edition of the Farmer's Almanac seems to agree with Seager and his colleagues.

Published earlier this week, the Almanac called for "colder-than-normal winter temperatures" in the winter of 2010-11, but added that, overall, Americans could expect "a kinder and gentler winter, especially in the areas that had a rough winter last year," according to NJ.com's Rohan Mascarenhas, a Star-Ledger reporter.

Furthermore, Mascarenhas said, the National Weather Service's "long-term outlook shows a near-normal winter, with temperatures and precipitation hewing close to average"¦ 'We shouldn't be seeing nearly as much snowfall as last winter,' said Kristin Kline, a meteorologist with the weather service."


On the Net: