Winter Precipitation Trends
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While every region of the country has seen a rise in winter temperatures since 1970, precipitation trends paint a more varied picture. Some regions have seen an increase in winter precipitation, while others have seen a decrease.
The biggest changes in winter precipitation trends since 1970 come from opposite corners of the country — the Southeast and the Northwest. The Southeast is down .182" per decade, with Georgia and South Carolina showing the starkest drying trend. The Northwest is down .136" per decade, with the largest decreases along the immediate coast and the crest of the Cascade Mountains. Lighter snowpack in the Cascades is bad news for skiers, as well as the region’s hydropower generators, which account for 40 percent of the nation’s hydropower generation.
The Northeast and the Northern Rockies round out the list of regions experiencing a decrease, though the trends there are minimal compared to other areas.
Meanwhile, a large chunk of land from California to Ohio has seen an uptick in winter precipitation since 1970. The largest regional increases are across the West at .081" per decade and the Ohio Valley at .067" per decade. Within those areas, northern California has had the biggest local increase, though Californians might have a hard time believing it this year as 2013 is on target to be one of the state’s driest years on record.
Though the Southwest is getting drier annually, it bucks that trend in the winter. Since 1970, the Southwest has experienced a rise in winter precipitation at .037" per decade. The Upper Midwest (+.03") and South (+.05") are also trending upward with winter precipitation.
This year's meteorological winter is already off to a big start for precipitation, and mostly in the form of snow. As of December 15, 53 percent of the country had snow on the ground. That’s the largest snowpack for the U.S. in a decade.