The daily AAO indices are shown for the previous 120 days, and the GFS forecasts of the daily AAO index at selected lead times are appended onto the time series. The indices are standardized by standard deviation of the observed monthly AO index from 1979-2000. A 3-day running mean is applied to the forecast time series.

The values at the upper left and right corner of each figure indicate the mean value of the AAO index and the correlation coefficients between the observation and the forecasts, respectively.

• Time series of the difference between 15-day running mean values of the observation and the outlooks