Report: The Case of the Shifting Snow — Climate Central

Click here to read the report. Here’s an excerpt:

Whether you live among palm trees or pine trees, snow plays a critical role in our climate. Snow keeps our planet cooler, significantly affects water resources, and is a revealing indicator of climate change.

Forecasting snowfall and determining long-term trends of snow climatology are inherently challenging, but the research team at Climate Central has produced an analysis of snowfall trends across the United States. While no single overall national trend in snowfall can be discerned from the results, clear regional and seasonal patterns do emerge. In almost all areas of the country, snow is decreasing in the “shoulder” seasons—fall and spring. Results from 145 locations show that 116 stations (80%) had decreased snowfall before December, and 96 stations (66%) had decreased snowfall after March 1. Winter showed a mixed record, with more snow in northern climates, and decreasing snow in the southern regions. We also compared total snowfall from the 1970s to the 2010s and ranked the 20 cities with the biggest percentage gains and losses, using endpoint analysis.

The changing patterns of how much, when, and where snow falls have significant impacts on our climate, our economy, and our lives. This report provides a primer on the climatology of snow and includes resources on how to report on snow—or the lack of it—in your area.

GLOBAL WARMING AND ITS IMPACT ON SNOW

Temperature is obviously the major factor in whether precipitation falls to the ground as snow, ice, or rain. As the surface temperature of the earth continues to rise, it’s already impacting snowfall patterns and amounts. Common sense tells us that a warmer climate will have less snowfall, as warmer temperatures are likely to make the snow melt to rain before it hits the earth, or melt it quickly when it hits the ground. In the United States, winters are the fastest warming season, the longest cold snaps are becoming shorter, and the number of days with temperatures below 32°F is expected to continue to decline across the country.

Counterintuitively, global warming could actually cause colder regions to experience greater snowfall in the near to medium term. That’s because warmer air “holds” more moisture—about four percent more per degree (F)—and that additional moisture can fall as snow when temperatures are below freezing.

According to ongoing academic research, warmer surface temperatures and reduced Arctic sea ice may also be leading to changing atmospheric circulation patterns that bring cold events to the eastern United States.

Graphic credit: Climate Central

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