Rainfall
Seasonal Rainfall Outlook: February-April 2021 (FMA)
Issued: 31 Jan 2021
For FMA 2021, there is an increased chance of above-normal rainfall for most of the ASEAN region north of the equator.
For FMA 2021, all three models – NCEP, ECMWF, and UK Met Office (Figures 1-3) – predict an increased chance of above-normal rainfall over the Philippines and northern Borneo as well as much of central and southern Myanmar, Thailand, Cambodia and southern Viet Nam. The ECMWF (Figure 2) and UKMO (Figure 3) models also predict above-normal rainfall for Peninsula Malaysia, while the NCEP model (Figure 1) predicts near- to above-normal rainfall. The model skill for the above-normal tercile category is moderate to relatively good for the band around 10°N, which includes much of the region where above-normal rainfall is predicted apart from central Myanmar and the northern half of Thailand, where the model skill is low to moderate.
The three models also predict an increased chance of below-normal rainfall for parts of Sumatra, western Borneo and Sulawesi. However, the model skill is only low to moderate for these regions.
Elsewhere, there is no dominant tercile between the models, or the model skill is low.
Figure 1: Rainfall tercile summary predictions of NCEP model for FMA 2021.
Figure 2: Rainfall tercile summary predictions of ECMWF model for FMA 2021 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for FMA based on CHIRPS (Reference period: 1981-2010).
Figure 6: Average climatological rainfall's upper tercile boundary for FMA 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.