This is the third essay of the series of commonly analyzed teleconnections. Teleconnections are weather patterns that help produce long term forecasts (beyond 5 days). Pressure patterns in the atmosphere tend to promote certain weather patterns. The third teleconnection we will look at is the Arctic Oscillation (AO). Positive values: The U.S. East of the Rocky Mountains tends to be warmer. The pressure is higher in the mid-latitudes and lower at the poles and this reduces cold air outbreaks. The western U.S. tends to be drier. Over the past several decades the value has tended to be positive. Negative values: The U.S. East of the Rocky Mountains tends to be colder. The pressure is lower in the mid-latitudes and higher at the poles and this increases cold air outbreaks. Current values are available at: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index.html |