January 2014 was remarkably mild across nearly all of Alaska, resulting in this January ranking among the  “top ten” warmest on record for many Alaskan communities according to preliminary analyses.

The Arctic Oscillation describes simultaneous, geographically “choreographed” shifts in multiple features of the polar vortex: air pressure, temperature, and the location and strength of the jet stream. They all follow the hemisphere-wide oscillation of atmospheric mass back and forth between the Arctic and the middle latitudes, sort of like water sloshing in a bowl.

A few days of unusually cold weather in the U.S. and Canada aren't a sign that a century-or-more trend of rising global surface temperatures has reversed itself. In fact, the cold wasn't even all that widespread for the Northern Hemisphere.

Meteorologists have known for years that the pattern of the polar vortex determines how much cold air escapes from the Arctic and makes its way to the U.S. during the winter. Climate scientists are wondering if a warmer Arctic could explain its odd behavior in recent years.

October in Alaska this year was more like September, with warmth and rain in place of autumn chill and snow. Wind anomalies related to unusual pressure patterns conspired to bring a steady stream of warm, wet air from southerly latitudes into Alaska.

For much of Alaska, lack of snow, soaking rains, and record-warmth have made October feel more like September.

Much colder-than-average temperature during March and a strongly negative Arctic Oscillation Index reminded people in the United States how important this index is to our own climate conditions.

As the whole ocean gets warmer, NOAA scientists must redefine what they consider “average” temperature in the central tropical Pacific, where they keep watch for El Niño and La Niña.

Deke Arndt, Chief of the Climate Monitoring Branch, at the National Climatic Data Center talks about the influence of La Niña on the 2011 global average temperature. 

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