Rainfall
Seasonal Rainfall Outlook: May-July 2023 (MJJ)
For MJJ 2023, below-normal rainfall is predicted over much of the southern ASEAN region.
For MJJ 2023, based on the multi-model ensemble (Figure 4), there is an increased chance of below-normal rainfall for much of the southern ASEAN region. All three models (Figures 1 – 3) show the highest probabilities of below-normal rainfall over the western half of this region. The models’ skill for below-normal rainfall is low to moderate for the western Maritime Continent and moderate to high for the rest of the southern ASEAN region.
For the northern ASEAN region, overall, there is a small increase in chance of above-normal rainfall over some parts, including Philippines and western coastal region of Mainland Southeast Asia and no dominant tercile elsewhere, based on the multi-model ensemble. While the ECMWF and UK Met Office models predict near- to above-normal rainfall for much of the region (Figures 2 and 3), the NCEP model predicts a higher chance of below-normal rainfall over this region (Figure 1). The model’s skill is low to moderate for much of the northern ASEAN region.
Figure 1: Rainfall tercile summary predictions of NCEP model for MJJ 2023 (contains modified Copernicus C3S information).
Figure 2: Rainfall tercile summary predictions of ECMWF model for MJJ 2023 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for MJJ 2023 (contains modified Copernicus C3S information).
Figure 4: Rainfall tercile summary predictions of the multi-model ensemble for MJJ 2023 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for MJJ based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for MJJ 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.