Rainfall
Monthly Rainfall Outlook: November 2021
Issued: 29 Oct 2021
For November 2021, there is an increase in chance of above-normal rainfall over much of the Maritime Continent and parts of southern Mainland Southeast Asia.
For November 2021, based on the multi-model ensemble (Figure 4), there is an increase in chance of above-normal rainfall over much of the Maritime Continent, apart from Sumatra where below-normal rainfall is the dominant tercile, and the Philippines where there is no dominant tercile. The highest likelihood for above-normal rainfall for all three models is over southern and southeastern parts of the Maritime Continent (Figures 1 to 3). The models’ skill is relatively high for southern and eastern parts of the region, and low to moderate elsewhere.
For Mainland Southeast Asia, there is also an increase in chance of above-normal rainfall over parts of southern Mainland Southeast Asia based on the multi-model ensemble (Figure 4). Over northeastern parts of the region, the NCEP model (Figure 1) and the ECMWF model (Figure 2) predict an increase in chance of below-normal rainfall, while the UKMO model predicts no dominant tercile (Figure 3). Elsewhere, there is disagreement between the models, or no dominant tercile predicted. The models’ skill is low for Mainland Southeast Asia, apart from southern parts of Mainland Southeast Asia where there is moderate skill.
Figure 1: Rainfall tercile summary predictions of NCEP model for November 2021.
Figure 2: Rainfall tercile summary predictions of ECMWF model for November 2021 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for November 2021 (contains modified Copernicus C3S information).
Figure 4: Rainfall tercile summary predictions of the multi-model ensemble for November 2021 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for November based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for November 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.