Rainfall
Monthly Rainfall Outlook: August 2021
Issued: 30 Jul 2021
For August 2021, there is an increase in chance of above-normal rainfall over much of the Maritime Continent.
For August 2021, based on the multi-model ensemble (Figure 4), there is an increase in chance of above-normal rainfall over much of the Maritime Continent, apart from northern Sumatra, the Malay Peninsula, and the northern Philippines where there is no agreement in the models. The ECMWF and UK Met Office models (Figures 2 and 3) have the highest likelihood of above-normal rainfall over central and southern parts of the Maritime Continent, while the NCEP model predicts the highest likelihood over southern Sumatra and Java (Figure 1). The models’ skill is relatively high for much of the Maritime Continent, apart from northern Sumatra, the Malay Peninsula, and the northern Philippines where the skill is only low to moderate.
Elsewhere in Mainland Southeast Asia, there is either no dominant tercile predicted or the models’ skill is low.
Figure 1: Rainfall tercile summary predictions of NCEP model for August 2021.
Figure 2: Rainfall tercile summary predictions of ECMWF model for August 2021 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for August 2021 (contains modified Copernicus C3S information).
Figure 4: Rainfall tercile summary predictions of the multi-model ensemble for August 2021 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for August based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for August based on CHIRPS (Reference period: 1991-2020).
The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.