Westerly winds bring hotter, drier weather.

• Position: American Southwest - Brief article

Human-driven changes in the westerly winds are bringing hotter and drier springs to the American Southwest, according to research from the University of Arizona, Tucson. Since the 1970s, the winter storm track in the western U.S. has been shifting north, particularly in late winter. As a result, fewer winter storms drop rain and snow on Southern California, Arizona, Nevada, Utah, and western Colorado and New Mexico.

"We used to have this season from October to April where we had a chance for a storm. Now it's from October to March," contends Stephanie McAfee, a doctoral candidate in the Department of Geosciences.

The finding is the first to link the poleward movement of the westerly winds to the changes observed in the West's winter storm pattern. The change in the westerlies is driven by the atmospheric effects of global warming and the ozone hole combined. "When you pull the storm track north, it takes the storms...