Rainfall

For September’s rainfall, all three models – NCEP CFSv2, ECMWF, and UK Met Office (Figures 1-3) – predict below-normal conditions over parts of the equatorial region (around southern Sumatra, Borneo, Sulawesi, and Papua), as well as over the coastal regions of northern Southeast Asia (north of 10˚N). The spatial extent and magnitude of the likelihood for below-normal conditions differ across the different models. In particular, for NCEP CFSv2, the likelihood for below-normal rainfall is higher than ECMWF or the UK Met Office. Furthermore, only NCEP CFSv2 favours above-normal conditions along the 10˚N latitude stretch, where the other two models predict below-normal or no dominant tercile.

The models’ skill for rainfall prediction are very good over south of the equator and moderate along the 10˚N stretch.

Figure 1: Rainfall tercile summary predictions of NCEP model for September 2018.