Rainfall
Monthly Rainfall Outlook: April 2021
Issued: 30 Mar 2021
For April 2021, models predict above-normal rainfall over the Philippines, northeastern Borneo, northern Sulawesi and Mainland Southeast Asia.
For April 2021, above-normal rainfall is predicted over the Philippines, northeastern Borneo, northern Sulawesi and parts of Mainland Southeast Asia as seen in the multi-model ensemble (Figure 4). While the ECMWF (Figure 2) and the UK Met Office models (Figure 3) predict a larger region with above-normal rainfall, extending further west to include most of Mainland Southeast Asia, the NCEP model (Figure 1) predicts the wet conditions mainly over central parts of Mainland Southeast Asia. The models’ skill is moderate to relatively good for the Philippines, northeastern Borneo, northern Sulawesi and southern Mainland Southeast Asia, with low to moderate skill for northern Mainland Southeast Asia.
While all three models predict below-normal rainfall for Sumatra, western and central Borneo and southern Sulawesi, the model skill for these regions is generally low.
Elsewhere, there is either disagreement between the models (Peninsular Malaysia) or the model skill is low (Java region) for this time of the year.
Figure 1: Rainfall tercile summary predictions of NCEP model for April 2021.
Figure 2: Rainfall tercile summary predictions of ECMWF model for April 2021 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for April2021 (contains modified Copernicus C3S information).
Figure 4: Rainfall tercile summary predictions of the multi-model ensemble for April 2021 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for April based on CHIRPS (Reference period: 1981-2010).
Figure 6: Average climatological rainfall's upper tercile boundary for April based on CHIRPS (Reference period: 1981-2010).
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.