Rainfall
Seasonal Rainfall Outlook: March-May 2021 (MAM)
Issued: 26 Feb 2021
For MAM 2021, there is an increased chance of above-normal rainfall for most of the ASEAN region north of the equator, and below-normal rainfall for much of Sumatra, Borneo and Sulawesi.
For MAM 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 ASEAN region north of the equator, except for northern Myanmar where there is disagreement between the models. The model skill for the above-normal tercile is moderate to good for the band around 10°N, which includes much of the region where above-normal rainfall is predicted except for northern Mainland Southeast Asia, where the model skill is low to moderate.
South of the equator, the three models are also in agreement with below- to near-normal rainfall for southern Sumatra, western Borneo, and Sulawesi. Near- to above-normal rainfall is also predicted for southern Indonesia. However, the model skill is only low to moderate for these regions.
Figure 1: Rainfall tercile summary predictions of NCEP model for MAM 2021.
Figure 2: Rainfall tercile summary predictions of ECMWF model for MAM 2021 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for MAM based on CHIRPS (Reference period: 1981-2010).
Figure 6: Average climatological rainfall's upper tercile boundary for MAM 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.