September 22, 2011 in Washington Voices

Solar activity may keep snow in check

Randy Mann
 

The National Weather Service earlier predicted that the chances of La Niña returning would be fifty-fifty. As mentioned before, La Niña is the abnormal cooling of sea-surface temperatures along the west coast of South America and the equatorial regions of the south-central Pacific Ocean. During this event, weather patterns often favor a snowier and colder winter for much of the northern U.S., including the Inland Northwest.

During the heavy snowfall years of 2007-’08, 2008-’09 and 2010-’11 we had a moderate to strong La Niña. Record-breaking snows were seen across the region as Spokane had a whopping 96.5 inches of snow during the 2008-’09 season. During the winter of 2007-’08, Coeur d’Alene received a record 172.9 inches of snow. Normally, the airport measures 45.6 inches of snow while Coeur d’Alene sees 69.8 inches. Spokane received only 14.4 inches of snow during a warmer El Niño cycle in 2009-’10.

Although La Niña years do favor colder and snowier winters across the Inland Northwest, not every event has brought the heavy snows to our region. For example, the La Niña winters of 1967-’68 and 1970-’71 averaged only 30 to 32 inches of snow at the airport.

By contrast, the La Niña winters of 1949-’50, 1955-’56, 1974-’75, 2007-’08 and 2008-’09 all observed snowfall totals above 80 inches. Last year, the airport received 69 inches of snow.

Our winters are certainly influenced by the abnormal warming and cooling of sea-surface temperatures. But sunspot activity, long-term climate cycles and other oscillations play a role as well. During the heavy snowfall seasons of three out of the last four years, sunspot activity (storms on the sun) were extremely low. The slight decrease of solar energy may have contributed to the harsh winters of 2007-’08, 2008-’09 and 2010-’11.

For this upcoming winter, I don’t believe we’ll see as much snow as last year, but totals may be near to slightly above normal. Solar activity has been increasing at a rather dramatic rate over the past several months. We’ve seen a number of solar flares as well. During the La Niña winters of 1967-’68 and 1970-’71, solar activity was relatively high. The sunspot numbers during those years are similar to the ones we have today.

In terms of temperatures for this winter, I wouldn’t be surprised to see some record-breaking lows with readings well below zero in December or January. During this cycle of extremes, when we see above-normal temperatures in September and October, our region often flips to the colder side in the late fall and early winter.


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