I saw the near record +PNA rise being discussed in Don's great thread. So I did some research into how it’s becoming more extreme with climate change. The PNA index isn’t the only one becoming more amplified. A study from 2009 documented how the NAO has also exhibited much bigger swings from high to low as the climate has warmed. In fact, the summer of 2009 to the present has exhibited record breaking highs and lows. The AO is showing these same extremes from record lows in the summer of 2009 th