Rainfall

For JJA 2024, above-normal rainfall is predicted for the equatorial region based on the multi-model ensemble (Figure 4). All three models predict above-normal rainfall with high confidence over Borneo and the eastern equatorial region (Figures 1 – 3). The ECMWF and NCEP models show also moderate to high confidence for above-normal rainfall over the western Maritime Continent, while the UK Met Office model predicts near- to above-normal rainfall. Models’ skill is overall good for above-normal rainfall over the equatorial region.

Elsewhere in the Maritime Continent, a mix of below- to near-normal rainfall is predicted based on the multi-model ensemble (Figure 4). The ECMWF and UK Met Office models agree with an increase in chance of below-normal rainfall over the northern half of the Philippines (Figures 2 – 3), while the NCEP model predicts a higher chance of near-normal rainfall for this region. For the southern Maritime Continent, the ECMWF and UK Met Office models predict a high chance of below-normal rainfall, while the NCEP model predicts near-normal rainfall. The models’ skill for below-normal rainfall is overall moderate over Philippines and the southern Maritime Continent.

Over Mainland Southeast Asia, the models predict above-normal rainfall for the southern part of the region and with a disagreement between the models or no dominant tercile elsewhere. 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.