Rainfall
Seasonal Rainfall Outlook: April-June 2023 (AMJ)
Issued: 30 Mar 2023
For AMJ 2023, below-normal rainfall is predicted over much of the western and central Maritime Continent, while above-normal rainfall is predicted parts of north-eastern Maritime Continent.
For AMJ 2023, based on the multi-model ensemble (Figure 4), there is an increased chance of below-normal rainfall for much of the western and central Maritime Continent. All three models show an increased chance of below-normal rainfall over this region (Figures 1-3), with the ECMWF model (Figure 2) showing the highest probabilities for below-normal tercile. The NCEP model (Figure 1) also shows below-normal rainfall over the eastern Maritime Continent.
There is also a small increase in chance of above-normal rainfall over the northeastern parts of the Maritime Continent, including southern Philippines and northeastern Borneo, based on the multi-model ensemble. The model skill for the Maritime Continent is generally low for below-normal rainfall tercile over the western and southern regions, and low to moderate for above-normal rainfall over the northeastern region.
For Mainland Southeast Asia, there is no dominant tercile predicted and individual models show disagreement for the tercile category for much of the region. The models’ skill for Mainland Southeast Asia is and low to moderate for below- or above-normal tercile.
Figure 1: Rainfall tercile summary predictions of NCEP model for AMJ 2023 (contains modified Copernicus C3S information).
Figure 2: Rainfall tercile summary predictions of ECMWF model for AMJ 2023 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for AMJ based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for AMJ 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.