|We Didn't See Much of This Last Winter|
Last winter gave us a great laboratory environment by which to view the atmosphere, like a fly on a wall, react to several teleconnections abrupt shift to levels that feature a lack of arctic drivers. This was a wake up call for all of us after a few very cold winters in 2009 and 2010. As a scientist, it was nice to see the other end of the spectrum at work in nature. Let's look at the late 2011 teleconnection levels:
The North Atlantic Oscillation, The Arctic Oscillation and the Pacific North American Index (Click on the link here for a detailed description)
Each one is more influential on weather patterns in the winter. The more POSITIVE the NAO and AO; the more NEGATIVE the PNA, the "colder" pattern shuts down. Conversely, the more NEGATIVE the NAO and AO; the more POSITIVE the PNA, the "colder" pattern becomes stronger and stronger.
North Atlantic Oscillation/Arctic Oscillation/Pacific North American Index charts from late 2011. Notice the perpetual POSITIVE levels. The PNA forecast for December 2011 was barely in positive (colder) territory.
along with a few other factors over the arctic and Siberia, expect more cold this winter than last.