Seasonal Forecast for January, February, March 2019

Updated 3 February 2019

Summary of Outlook

The Northeast Monsoon conditions typically extend into March before transitioning to the inter-monsoon period around April. Climatologically, the prevailing winds over the ASEAN region during this season blows from the northeast or northwest, with the monsoon rain band situated south of the Equator. This is the traditional dry season for the northern ASEAN region. Areas along the equatorial region may experience occasional dry weather, but scattered shower activities from the monsoon rain band are forecast further south.

Above-normal temperature conditions are favoured over most parts of Southeast Asia, especially along the equatorial region during the Feb-Mar-Apr season.

In Myanmar and many parts of the Philippines, drier conditions with rainfall below the climatological average are likely. There is a chance of above-normal rainfall over parts of the equatorial region, in particular over Malaysia, Sumatra and Kalimantan. Elsewhere, there is no dominant tercile.

During this traditional dry season, increased hotspot activities and hazy conditions are expected to persist in the Mekong sub-region. Elsewhere in the southern ASEAN region, hotspot activities are likely to remain subdued but isolated hotspots may emerge during brief periods of dry weather.

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.

For February 2019, below-normal rainfall is favoured over the Philippines, northern Borneo, and parts of Viet Nam and Myanmar. Elsewhere, no dominant tercile category is predicted.

 

For February’s rainfall, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 1a-c) predict an increased chance of below-normal rainfall over the Philippines, northern Borneo, and parts of Viet Nam and Myanmar. The highest probability of below-normal rainfall is over the Philippines. Model skill is relatively high over the Philippines at this time of year, with low to moderate skill for the other regions mentioned above.

For the rest of the Southeast Asia region, the model skill is either low, or there is no dominant tercile from the three models (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).

Rainfall Tercile Summary of NCEP model.

Figure 1a: Rainfall tercile summary predictions of NCEP model for February 2019.

Rainfall Tercile Summary of ECMWF model.

Rainfall Tercile Summary of Met Office model.

Figure 1b: Rainfall tercile summary predictions of ECMWF model for February 2019 (contains modified Copernicus C3S information). Figure 1c: Rainfall tercile summary predictions of UK Met Office model for February 2019 (contains modified Copernicus C3S information).

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. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for rainfall, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.

 


For FMA 2019, below-normal rainfall is favoured over the Philippines and Myanmar. Over the equatorial region, models predict an increased chance of above-normal rainfall, but there is some disagreement between models on the extent.

 

For FMA 2019, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 2a-c) predict below-normal rainfall over the Philippines and Myanmar. Overall, the models’ skill for rainfall are good over the Philippines and moderate over Myanmar.

Over the western equatorial region (Sumatra, Peninsular Malaysia, and Borneo), all three models predict near-normal to above-normal rainfall. The NCEP CFSv2 and UK Met Office models predict the near-normal to above-normal rainfall to extend further east (Sulawesi and Papua), while the ECMWF model predicts below to near-normal rainfall for this region. The models’ skill for this region is only low to moderate for the FMA season (NCEP, ECMWF, UK Met Office).

Elsewhere in the region, there is no consistent dominant tercile category predicted across the NCEP CFSv2, ECMWF and UK Met Office models.

Rainfall Tercile Summary of NCEP model.

Figure 2a: Rainfall tercile summary predictions of NCEP model for FMA 2019.

Rainfall anomaly of ECMWF model.

Rainfall Tercile Summary of Met Office model.

Figure 2b: Rainfall tercile summary predictions of ECMWF model for FMA 2019 (contains modified Copernicus C3S information). Figure 2c: Rainfall tercile summary predictions of UK Met Office model for FMA 2019 (contains modified Copernicus C3S information).

The qualitative outlook is assessed for the region in general, and based on the latest run from models provided by the SEA-RCC LRF node. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for rainfall, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.

For February 2019, above-normal temperature is favoured over most of Southeast Asia.

 

All three models – NCEP CFSv2, ECMWF, and the UK Met Office (Figures 1a-c) provide consistent outlook for above-normal temperature over most parts of the ASEAN region for February, but models differ significantly in the probabilities of above-normal temperature over Myanmar and the Philippines. In general, the magnitudes of the likelihood for above-normal temperature are higher for NCEP CFSv2 than the ECMWF and the UK Met Office models and are consistent with previous months’ outlooks.

Over most of Southeast Asia, the models’ skill for predicting above normal temperature is generally very good, except for some eastern parts of the region where the skill is only low to moderate (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).

Temperature Tercile Summary of NCEP model.

Temperature Tercile Summary of ECMWF model.

Figure 1a: Temperature tercile summary predictions of NCEP model for February 2019. Figure 1b: Temperature tercile summary predictions of ECMWF model for February 2019 (contains modified Copernicus C3S information).

Temperature Tercile Summary of Met Office model.

Figure 1c: Temperature tercile summary predictions of UK Met Office model for February 2019 (contains modified Copernicus C3S information).

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. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for temperature, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.


For FMA 2019, above-normal temperature is favoured over most of Southeast Asia.

 

For FMA 2019, all three models – NCEP CFSv2, ECMWF, and UK Met Office (Figures 2 a-c) favour above-normal temperature conditions over most parts of the region with the highest likelihood over the equatorial region. The three models are also predicting a high probability of equatorial FMA temperatures to be in the top 20% percentile, way above-normal ranges (Figures 3 a-c).

Over land across the region, the models’ skill for temperature prediction are generally very good for the FMA season (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).

Temperature Tercile Summary of NCEP model.

Figure 2a: Temperature tercile summary predictions of NCEP model for FMA 2019.

Temperature Tercile Summary of ECMWF model.

Temperature Tercile Summary of Met Office model.

Figure 2b: Temperature tercile summary predictions of ECMWF model for FMA 2019 (contains modified Copernicus C3S information). Figure 2c: Temperature tercile summary predictions of UK Met Office model for FMA 2019 (contains modified Copernicus C3S information).

Temperature QWA Quintile of NCEP model.

Figure 3a: Temperature Top 20% Percentile (Way above Normal) predictions of NCEP model for FMA 2019.

Temperature QWA Quintile of ECMWF model.

Temperature QWA Quintile of Met Office model.

Figure 3b: Temperature Top 20% Percentile (Way above Normal) predictions of ECMWF model for FMA 2019 (contains modified Copernicus C3S information). Figure 3c: Temperature Top 20% Percentile (Way above Normal) predictions of UK Met Office model for FMA 2019 (contains modified Copernicus C3S information).

The qualitative outlook is assessed for the region in general, and based on the latest run from models provided by the SEA-RCC LRF node. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for temperature, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.