Let’s see. The Old Farmer’s Almanac had this prediction about the 2011-2012 winter:
Winter temperatures will be about a degree C below normal, on average, with the coldest temperatures in late November, mid- and late December, mid- and late January, and early February. Precipitation and snowfall will be above normal in the east and slightly below normal in the west. The snowiest periods will be in early January, mid- to late January, and early February.
As of today, there is little evidence of any snow in the Kingston area. And unusually mild temperatures. This seems to be true for much of North America.
So what happened to winter?Â NASA climatologist Bill Patzert of the Jet Propulsion Laboratory tries to explain:
“First of all,” he explains, “we are experiencing a La NiÃ±a pattern of sea surface temperatures in the Pacific Ocean. This pushes the jet stream and the cold arctic air northward.”
“On top of that, this year’s Arctic Oscillation has been stronger.”
The Arctic Oscillation is a see-sawing pressure difference between the Arctic and lower latitudes. When the pressure difference is high, a whirlpool of air forms around the North Pole. Last year, the whirlpool motion was weaker, allowing cold air to escape from the polar regions and head southward to the US.
“This year the whirlpool has been more forceful, corralling the cold air and keeping it nearer the pole. That has reinforced the La NiÃ±a impact.”
Discover Magazine makes these reassuring observations:
But why?, you ask. Why have these [Arctic] oscillations been so weird? Unfortunately, Masters writes, we don”™t really know why these variations happen. Addressing the elephant in the room — I”™m looking at you, climate change — he says, “Climate models are generally too crude to make skillful predictions on how human-caused climate change may be affecting the AO, or what might happen to the AO in the future.”? But he notes that there are links between solar activity and sunspots and positive values and between arctic sea ice loss and negative values. Whether this year”™s strong positives are related to sunspots, though, isn”™t clear.
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