Meltdown: Increasing Rain as a Percentage of Total Winter Precipitation

Executive summary

• Analyses 65 years (1949-2004) of winter precipitation data from more than 2,000 weather stations in 42 states
• Finds a decrease in the percent of precipitation falling as snow in winter months for every region of the country

Northwest

• Finds the Pacific Northwest has been the hardest hit, with low elevation snow on a clear path toward oblivion: 81 and 91 percent of stations under 2,000 feet in Washington and Oregon, respectively, show a trend toward a lower percentage of winter precipitation falling as snow over the 65 years analyzed
• Finds 63 and 77 percent of stations in Washington and Oregon, and 64 and 82 percent of stations in Montana and Idaho recording lower percentage of precipitation falling as snow during the winter snow season at 2,000 to 5,000 feet

Southwest

• Finds 68 and 83 percent of stations in California and Arizona registered a lower percentage of winter precipitation falling as snow from 2,000 and 5,000 feet
• Finds 76 percent of stations in Arizona shifting to less snow from 5,000 to 8,000 feet, with no trend in California at this elevation

Great Plains

• Finds the Great Plains states, Nebraska, and Kansas saw particularly dramatic shifts, with between 69 and 81 percent of stations experiencing a lower percentage of winter precipitation falling as snow, from 2,000 to 5,000 feet

Midwest and East

• Finds between 60 and 82 percent of stations at elevations below 2,000 feet, in 16 states, showed a sizable shift toward a lower percentage of precipitation falling as snow
• Finds that in 6 of these states; Iowa, Michigan, Minnesota, Missouri, Virginia and West Virginia, more than 70 percent of stations showed this trend