Omaha World-Herald

Nancy's Almanac, Jan. 17

The historic winter of 2009-2010, which left much of the northern U.S. buried in snow, spawned more intense research into the "arctic oscillation," a climate pattern that has had a major impact on the past three winters.

In 2009-2010, the arctic oscillation effectively overrode the impact of El Niño, which otherwise would have stacked the odds against a snowy winter in the Central and Northern Plains. However, with the oscillation in record-setting negative territory, it set up a situation that allowed heavy snows to sack the region.

This year, an unusual and unremitting positive arctic oscillation has amplified the effects of La Niña, depriving the Northern Plains of snow during a year when it typically could expect to be hard-hit.

Telvent DTN recently hosted a webinar that offers a good explanation of what's happened this winter.

©2012 Omaha World-Herald. Original Article