Rainfall
Seasonal Rainfall Outlook: April-June 2021 (AMJ)
Issued: 30 Mar 2021
For AMJ 2021, there is an increased chance of above-normal rainfall for most of the ASEAN region from 7° north of the equator, and some chance of below-normal rainfall for much of Sumatra and Borneo.
For AMJ 2021, all three models – NCEP, ECMWF, and UK Met Office (Figures 1-3) – are in agreement of an increased chance of above-normal rainfall for much of the region over much of the ASEAN region from 7° north of the equator. The model skill for above-normal tercile is relatively good for the Philippines and low to moderate for Mainland Southeast Asia.
While the three models predict an increased chance of below-normal rainfall for parts of Sumatra and Borneo, the model skill is only low to moderate for these regions.
Elsewhere, there is either disagreement between the models (Java region) or the skill is low for this season.
Figure 1: Rainfall tercile summary predictions of NCEP model for AMJ 2021.
Figure 2: Rainfall tercile summary predictions of ECMWF model for AMJ 2021 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for AMJ based on CHIRPS (Reference period: 1981-2010).
Figure 6: Average climatological rainfall's upper tercile boundary for AMJ 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.