Rainfall
Seasonal Rainfall Outlook: August-October 2019 (ASO)
Issued: 30 Jul 2019
For ASO 2019, below-normal rainfall is favoured over most parts of the Maritime Continent. Some parts of northern Southeast Asia (southern parts of Myanmar, Thailand, Cambodia, Laos, and Vietnam) are predicted to have increased chances of above-normal rainfall.
For ASO 2019, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 1-3) predict below-normal rainfall over for most parts of the Maritime Continent. The probability for below-normal category does vary between the models, with the ECMWF (Figure 2) model showing a higher probability of below normal rainfall than the NCEP (Figure 1) and UK Met Office (Figure 3) models. Overall, the models’ skill scores for rainfall are relatively good over the Maritime Continent except for northern parts of Borneo, and Sumatra, as well as Peninsular Malaysia.
There is no consistent prediction for much of northern Southeast Asia, although there is increased likelihood for above-normal rainfall for select regions (e.g. southern coastal parts of Myanmar, Thailand, Cambodia, Laos, and Vietnam). Models’ skill scores for this region are also generally low for the ASO season.
Figure 1: Rainfall tercile summary predictions of NCEP model for ASO 2019.
Figure 2: Rainfall tercile summary predictions of ECMWF model for ASO 2019 (contains modified Copernicus C3S information).