Rainfall
Seasonal Rainfall Outlook: July-September 2019 (JAS)
Issued: 28 Jun 2019
For JAS 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, and Vietnam) are predicted to have increased chances of above-normal rainfall.
For JAS 2019, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 1-3) predict below-normal rainfall over most parts of Maritime Continent. The spatial extent of the affected areas and the likelihood for below-normal category is consistent across the different models, but it may reflect the models’ tendencies to over-predict effect of El Niño which is still uncertain. 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, and Vietnam). Models’ skill scores for this region are also generally low for the JAS season.
Figure 1: Rainfall tercile summary predictions of NCEP model for JAS 2019.
Figure 2: Rainfall tercile summary predictions of ECMWF model for JAS 2019 (contains modified Copernicus C3S information).