Lack of snow inhibits chill’s full impact

There’s nothing like a trek across bare ground to ease the impact of an arctic air mass. That’s what’s happened in recent days. Snow cover reflects incoming sunlight away, reducing warming. But, bare ground has the opposite effect. Its dark color absorbs sunlight, a process which produces warming The difference between bare and snow covered ground can be dramatic. A combination of snow cover, clear skies and little or no wind at night has been known to reduce temperatures 12 or more degrees. By the same token, daytime readings surge 6-12° when the ground is bare. Despite the bare ground, readings are running 15-20° below the highest levels of the past six unseasonably mild weeks. But, while eastern North American temperatures have cooled, the same pattern change has boosted readings dramatically to the west. In just the past three days, Fairbanks, Alaska has warmed from -40° to Monday’s 34°—a 74° increase!
-Tom Skilling