Rainfall

For July 2023, below-normal rainfall is predicted over much of the southern ASEAN region, with highest likelihood over the southwestern Maritime Continent based on the multi-model ensemble (Figure 4). The UK Met Office model shows the highest confidence for below-normal rainfall over the southwestern Maritime Continent (Figure 3), followed by the ECMWF model (Figure 2) and then the NCEP model (Figure 1). The ECMWF model (Figure 2) predicts below-normal rainfall for the southwestern and southern Maritime Continent, with near-normal rainfall for much of eastern Indonesia. Models’ skill is moderate to good for predicting below-normal rainfall and low to moderate for predicting near-normal rainfall for the southern ASEAN region.

For the northern ASEAN region, above-normal rainfall is predicted over much of southern Mainland Southeast Asia and parts of the Philippines based on the multi-model ensemble (Figure 4). The UK Met Office model (Figure 3) shows the highest confidence for above-normal rainfall over southern Mainland Southeast Asia, followed by the ECMWF model (Figure 2). The NCEP model (Figure 1) predicts a mix of near- to above-normal rainfall over southern Mainland Southeast Asia. There is either disagreement between the models or no dominant tercile predicted over the rest of Mainland Southeast Asia. The models’ skill is low for most of the northern ASEAN region, and low to moderate for southern Mainland Southeast Asia and the Philippines for predicting below- and above-normal rainfall.