Rainfall
Seasonal Rainfall Outlook: November 2021 - January 2022 (NDJ)
Issued: 29 Oct 2021
For NDJ 2021-2022, there is an increased chance of above-normal rainfall over southern and eastern parts of the Maritime Continent, as well as southeastern parts of Mainland Southeast Asia.
For NDJ 2021-2022, all three models – NCEP, ECMWF and UK Met Office (Figures 1-3) predict an increased chance of above-normal rainfall for much of the Maritime Continent, with highest likelihood over southern and eastern parts of the Maritime Continent. No dominant or below-normal terciles are predicted for Sumatra and eastern Borneo. The models’ skill is moderate to relatively high for southern and eastern parts of the Maritime Continent and low to moderate elsewhere.
For Mainland Southeast Asia, there is an increase in chance of above-normal rainfall predicted by all three models for the southeastern region. The multi-model ensemble (Figure 4) has an increased chance of below-normal rainfall for northeastern Mainland Southeast Asia, with NCEP model the most confident of below-normal rainfall, while the ECMWF and UKMO models only predict a small increase in chance. However, model skill is low for this season, apart from moderate to relatively good skill for southeastern Mainland Southeast Asia.
Figure 1: Rainfall tercile summary predictions of NCEP model for NDJ 2021-2022.
Figure 2: Rainfall tercile summary predictions of ECMWF model for NDJ 2021-2022 (contains modified Copernicus C3S information).
Figure 5: Average climatological rainfall's lower tercile boundary for NDJ based on CHIRPS (Reference period: 1991-2020).
Figure 6: Average climatological rainfall's upper tercile boundary for NDJ 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.