this phenomenon by exploring the long-term trend of the reanalysis products for the wind plant with one of the highest reported reference wind speed data uncertainties (EIA ID 60502 reported 3.7% reference wind speed data uncertainty). Figure \[long\_ws\] shows the result. The period of record for wind plant operation (shown by a shaded blue area in Figure \[long\_ws\]) was only 12 months. As shown in the figure, the various reanalysis products have very different interpretations of the wind resource in the short period of record relative to the long-term (ERA-I: 4% above average; MERRA-2: 1% below average; NCEP-2: 1% above average). Consequently, the use of each reanalysis product will lead to different magnitudes (both positive and negative) in the long-term windiness corrections, leading to high uncertainty in the resulting operational AEP calculation. By increasing the period of record (i.e., increasing the number of data points used in the regression), such discrepancies tend to average out. This is illustrated in Figure \[lt\_ratio\], where we show how the period of record to long-term wind speed ratio varies as we extend the period of record by increasing the number of months while keeping December 2017 as the fixed ending time. For short periods 