Climate Fact: Regional Snow Trends
In Brief: Higher temperatures are reducing America’s snowfall, with a few regional exceptions.
Snow is not just an inhibitor of holiday travelers, nor is it just a passive product of prevailing weather conditions. Snow is a weather maker in and of itself. Snow-covered ground reflects far more of the sun’s radiation than it otherwise would and more reflection means lower temperatures at the surface. Because surface temperatures influence atmospheric circulation, understanding trends in snow and ice cover are crucial for effectively modeling weather and climate. Records indicate that as temperatures have risen, the southern margin where snow falls has moved north. This means that less snow is falling/accumulating in the mountains of the Western U.S., the Mid-Atlantic and the Kansas-Missouri regions. In the Western U.S., where 75 percent of year-round water sources originate from snow melt in the mountains, the trends have been particularly pronounced. Parts of the Northwest are receiving about half of the snowfall they received in the 1930′s. New England’s snowfall trends have been relatively flat. On the other hand, higher temperatures mean more moisture in the air. Regions such as the eastern side of the Rocky Mountains, particularly the eastern parts of Colorado and New Mexico, are now getting more snowfall as it is still cold enough for snow and there is more water in the air. The Great Lakes/northern Ohio Valley regions are also getting more snow, which is probably due to less ice cover on the Great Lakes. Less ice cover makes more lake effect snow possible.
(Source: Kunkel, KE et al. “Trends in Twentieth-Century U.S. Snowfall Using a Quality-Controlled Dataset.” Journal of Atmospheric and Oceanic Technology 26 (2009): 33-44.)
