Monday, January 9, 2012

Dear Europe: Arctic Oscillation About to Go Negative, Try to Stay Warm

Florida too.
Time for a little Trading Places? FCOJ closed limit up, +5.63% at 187.75. That is the second or third limit up in the last week.
A couple charts via Mother Jones:
...The National Snow and Ice Data Center's (NSIDC) latest polar ice report is in and the big news is that this winter might be a lot different from last, even though we're still in the middle of a La NiƱa.

The reason is the appearance of a mostly positive phase of the Arctic Oscillation (AO), which tends to produce less snow and warmer-than-average temperatures over the wintertime North America and Eastern Europe.
Daily Arctic Oscillation Index values from the NOAA Climate Prediction Center, Sept 2011 to Jan 2012, showing relative pressure anomalies between polar and mid-latitude regions. :  Credit: NSIDC courtesy NOAA NWS Climate Prediction Center. 
Daily Arctic Oscillation Index values from the NOAA Climate Prediction Center, Sept 2011 to Jan 2012, showing relative pressure anomalies between polar and mid-latitude regions. : Credit: NSIDC courtesy NOAA NWS Climate Prediction Center.

Last winter saw the opposite: tons of snow and really cold temps over much of North America and Europe and warmer-than-normal conditions over much of the Arctic. That's because a negative Arctic Oscillation took hold. I wrote about that here.

Arctic Oscillation: positive phase (left) has higher air pressure in mid-latitudes than in Arctic, leading to milder winter for US; negative phase (right) has higher air pressure over Arctic, pushing frigid, wet air into US.: Credit: NASA. 
Arctic Oscillation: positive phase (left) has higher air pressure in mid-latitudes than in Arctic, leading to milder winter for US; negative phase (right) has higher air pressure over Arctic, pushing frigid, wet air into US.: Credit: NASA.Technically, the Arctic Oscillation is a measure of atmospheric pressure variations at sea level north of 20N latitude. Where an Arctic high develops affects weather thousands of miles away.

Last year the so-called "Arctic fence" that keeps cold air penned up in the north broke down, allowing frigid air to spill south. So far that's not happening this winter. Though the AO is a fickle—not seasonal—phenomenon and can switch up at any time....
Here are the ensemble model runs at NOAA's Climate Prediction Center.
For a major change the index has to go below and stay below the zero line for at least a few weeks/