If you were to look at a U.S. snow cover map from December 2010 and compare it to the current U.S. snow cover you would notice quite a difference. This time last year we were dealing with several inches of snow and this year...none! Places in New Mexico still have snow on the ground from recent storms. While we have entered into another La Nina pattern the colder outbreaks have not been as frequent because the major storm track has been, for the most part, positioned from southwest to northeast. This has left us on the 'mild' side of the jet stream. Sure, we've had a few cold spells but temperatures have been running above average for awhile. A big factor as to why it's been fairly mild and quiet is the fact that the NAO (North Atlantic Oscillation) has been positive -
read more on the NAO here. Last year, as with previous years, the NAO was negative which allowed more cold air to move south, keeping the storm track south and giving us the colder and snowier December. This year the NAO has remained positive which keeps the jet stream further north not allowing the cold air to invade the southern states. Unfortunately, it doesn't look like this pattern will break any time soon.
If you were to look at a U.S. snow cover map from December 2010 and compare it to the current U.S. snow cover you would notice quite a difference. This time last year we were dealing with several inches of snow and this year...none! Places in New Mexico still have snow on the ground from recent storms. While we have entered into another La Nina pattern the colder outbreaks have not been as frequent because the major storm track has been, for the most part, positioned from southwest to northeast. This has left us on the 'mild' side of the jet stream. Sure, we've had a few cold spells but temperatures have been running above average for awhile. A big factor as to why it's been fairly mild and quiet is the fact that the NAO (North Atlantic Oscillation) has been positive - read more on the NAO here. Last year, as with previous years, the NAO was negative which allowed more cold air to move south, keeping the storm track south and giving us the colder and snowier December. This year the NAO has remained positive which keeps the jet stream further north not allowing the cold air to invade the southern states. Unfortunately, it doesn't look like this pattern will break any time soon.
I'm enjoying the relatively mild weather. After all, it's only mid-December. There is plenty more winter ahead of us for cold weather and snow. It wouldn't hurt my feelings if we didn't have a big snow until Jan or Feb!
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