The forecasting skill of the Hong Kong Observatory Global-Regional Climate Model (G-RCM) suite is evaluated by the Scaled Hanssen and Kuipers Score (Ks) recommended by WMO. Ks is 0 when forecasts are totally missed and is 1 when forecasts are perfect. The skills of G-RCM based on the performance in the past 26 years (1981-2006) are shown below.

Table 1. Ks of G-RCM seasonal rainfall forecast
Season
Ks for forecasting below normal rainfall
Ks for forecasting near normal rainfall
Ks for forecasting above normal rainfall
Mar-Apr-May (MAM)
0.56
0.52
0.54
Jun-Jul-Aug (JJA)
0.52
0.42
0.54
Sep-Oct-Nov (SON)
0.49
0.47
0.47
Dec-Jan-Feb (DJF)
0.44
0.48
0.60

Table 2. Ks of G-RCM seasonal temperature forecast
Season
Ks for forecasting below normal temperature
Ks for forecasting near normal temperature
Ks for forecasting above normal temperature
Mar-Apr-May (MAM)
0.59
0.48
0.64
Jun-Jul-Aug (JJA)
0.56
0.52
0.57
Sep-Oct-Nov (SON)
0.55
0.49
0.55
Dec-Jan-Feb (DJF)
0.56
0.55
0.59