October 20, 2011 in Washington Voices

La Niña winter won’t necessarily be extreme


A recent study published in Nature Geosciences supports the idea that when the sun’s intensity weakens, winter weather patterns in the U.S. and northern Europe favor colder and snowy weather.

Scientists examined how weather patterns were changed when the amount of solar radiation reaching Earth rises and falls over time. Based on computer models of the atmosphere and ocean, the study determined that low solar activity often leads to cold winters in northern Europe and the United States. In contrast, the winters are milder over southern Europe and Canada.

There have also been other links with low solar activity and colder weather. During the “little ice age,” a time of extreme cooling, there was an extended period of little sunspot activity (solar storms) in the 17th century, called the Maunder Minimum. During one 30-year period within the Maunder Minimum, only 50 sunspots were seen. Normally, astronomers see approximately 40,000 to 50,000 sunspots during a 30-year time span.

Storms on the sun have been rebounding over the past three to six months as the sun is heading toward a new solar maxima cycle. Although La Niña, the cooler-than-normal sea-surface temperature event, is gaining strength once again, the upcoming winter may not be as severe in the northern U.S. as many are predicting.

There have been winters during La Niña years when snowfall was actually below normal in parts of the northern U.S. and southern Canada. During those winters, the number of solar storms was higher and similar to ones we have today. But, there are other long-term and short-term climatic cycles and atmospheric phenomena that ultimately dictate our winter weather.

I believe that the northern regions of the U.S. will experience near to slightly above-normal snowfall this winter. But, in this cycle of wide weather extremes, anything can happen.

Based on current information, Spokane International Airport should end up with approximately 49 to 53 inches of snow this season. The normal is about 46 inches. I predict 52 to 56 inches of snow in Spokane Valley with 55 to 59 inches falling on Spokane’s South Hill.

Coeur d’Alene’s snowfall total is projected to be around 77 to 81 inches. The first measurable snowfall over much of the region is expected near Veterans Day, Nov. 11.

Area ski resorts should range from approximately 188 inches at Mount Spokane to around 340 inches at both Lookout Pass and Montana’s Whitefish Mountain (Big Mountain). At least Lookout Pass will be open for skiing by the Thanksgiving holiday weekend. The other ski resorts may not have enough snow to open until early December. But, as usual, only time will tell.

Contact meteorologist Randy Mann at randy@longrange weather.com.

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