Rainfall
Seasonal Rainfall Outlook: August-October 2022 (ASO)
Issued: 31 Jul 2022
For ASO 2022, above-normal rainfall is predicted for much of the southern ASEAN region, apart from below-normal rainfall over the western Maritime Continent.
For ASO 2022, based on the multi-model ensemble (Figure 4), there is an increased chance of above-normal rainfall for much of the southern ASEAN region, apart from the western Maritime Continent where below-normal rainfall is predicted. Among the three models – the UK Met Office model (Figure 3) predicts above-normal rainfall for the largest region, while the ECMWF model (Figure 2) predicts below-normal rainfall over parts of the western Maritime Continent and northern Borneo, and the NCEP model (Figure 1) predicts below-normal rainfall over parts of the western Maritime Continent. The models show low to moderate skill over the western Maritime Continent and moderate to good skill over the rest of the Maritime Continent.
For the northern ASEAN region, there is a slight increase in chance of above-normal rainfall for the northern half of Mainland Southeast Asia as well as over the Philippines. However, the model skill is low to moderate for the mentioned regions. Elsewhere in the northern ASEAN region, there is either disagreements between the models or the models' skill is low for this season.
Figure 1: Rainfall tercile summary predictions of NCEP model for ASO 2022 (contains modified Copernicus C3S information).
Figure 2: Rainfall tercile summary predictions of ECMWF model for ASO 2022 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for ASO 2022 (contains modified Copernicus C3S information).
Figure 4: Rainfall tercile summary predictions of the multi-model ensemble for ASO 2022 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for ASO based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for ASO 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.