Rainfall
Seasonal Rainfall Outlook: July-September 2024 (JAS)
Issued: 30 Jun 2024
For JAS 2024, above-normal rainfall is predicted for the equatorial region.
For JAS 2024, above-normal rainfall is predicted for the equatorial region based on the multi-model ensemble (Figure 4). The NCEP and UK Met Office models (Figures 1 and 3) predict above-normal rainfall for this region with higher confidence over Borneo and the eastern equatorial region. The ECMWF model (Figure 2) shows a mix of near- to above-normal rainfall over this region, with higher confidence of above-normal rainfall over the eastern equatorial region. Models’ skill is overall good for above-normal rainfall over the central to eastern equatorial region, and moderate to good for the western region.
Elsewhere in the Maritime Continent, a mix of below- to above-normal rainfall is predicted over the Philippines based on the multi-model ensemble (Figure 4), while there is disagreement between the models for the southern Maritime Continent. Models’ skill is poor to moderate over Philippines and good over the southern Maritime Continent.
Over Mainland Southeast Asia, the models predict above-normal rainfall for much of the region. Model skill is generally low for Mainland Southeast Asia at this time of the year, apart from over the southern parts, where model skill is low to moderate.
Figure 1: Rainfall tercile summary predictions of NCEP model for JAS 2024 (contains modified Copernicus C3S information).
Figure 2: Rainfall tercile summary predictions of ECMWF model for JAS 2024 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for JAS 2024 (contains modified Copernicus C3S information).
Figure 4: Rainfall tercile summary predictions of the multi-model ensemble for JAS 2024 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for JAS based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for JAS 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.