Rainfall
Seasonal Rainfall Outlook: September-November 2018 (SON)
Issued: 31 Aug 2018
For SON 2018, near-normal or below-normal rainfall is favoured over most parts of the Southeast Asia region.
For SON 2018, all three models – NCEP CFSv2, ECMWF, and UK Met Office (Figures 1-3) –differ over the equator and southwards. For this region, NCEP CFSv2 predicts mostly below-normal rainfall, whereas ECMWF and UK Met Office predict a mix of near-normal and below-normal rainfall. For all three models, however, the magnitude of the below-normal rainfall is not expected to be large. All three models have good skill over the equator and southwards.
Elsewhere, the three models favour below-normal conditions over the northern parts of Southeast Asia. Another consistent prediction across the three models is over northern Sumatra and Peninsular Malaysia where above-normal rainfall is favoured. However, for both these regions, model skill in this season is generally poor, apart from over the northern Philippines.
Figure 2: Rainfall tercile summary predictions of ECMWF model for SON 2018 (contains modified Copernicus C3S information).
Figure 3: Rainfall tercile summary predictions of UK Met Office model for SON 2018 (contains modified Copernicus C3S information).