Seasonal Forecast for November-December-January 2019/2020

Updated 31 October 2019

Summary of Outlook

The inter-monsoon period usually transitions into the Northeast Monsoon season in November or early December. The Northeast Monsoon season is associated with the traditional dry season in the northern ASEAN region, and with the traditional rainy season in the southern ASEAN region. The prevailing winds in the region during the Northeast Monsoon season typically blow from the northwest or northeast.

For the next three months, below-average rainfall is predicted over most parts of the southern ASEAN region. Warmer-than-average conditions are likely to prevail over much of the ASEAN region.

For November 2019, there may be isolated hotspot activities in the southern ASEAN region during dry periods. However, the hotspot situation is expected to gradually improve with an increase in showers with the onset of the Northeast Monsoon season.

In the northern ASEAN region, hotspot activities are expected to be generally subdued in November, but gradually increase towards the end of the year with the onset of the dry season.

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 November 2019, below-normal rainfall is favoured over most of equatorial and southern Southeast Asia. Elsewhere, predictions either are not consistent across models, or have less skill.

 

For November 2019, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 1a-c) – continue predicting an increased chance of below-normal rainfall for most parts of equatorial and southern Southeast Asia. The skill is generally highest south of the Equator where all three models tend to have moderate to high skill. Near the equator, however, the models have only low to moderate skill.

For northern Southeast Asia, the three models differ in their predictions. The NCEP model predicts a higher chance of above-normal-rainfall for much of the region, while the ECMWF model predict mainly below-normal to near-normal rainfall, and the UKMO model predicts no dominant tercile for the region. The model skill for November is generally poor for much of Northern Southeast Asia for November, apart from higher skill over parts of Viet Nam and the Philippines (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).

Rainfall Tercile Summary of NCEP model.

Rainfall Tercile Summary of ECMWF model.

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

Rainfall Tercile Summary of UK Met Office model.

Rainfall Tercile Summary of MME model.

Figure 1c: Rainfall tercile summary predictions of UK Met Office model for November 2019 (contains modified Copernicus C3S information). Figure 1d: Rainfall tercile summary predictions of multi-model ensemble model for November 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 NDJ 2019-2020, below-normal rainfall is favoured over most of the southern Southeast Asia.

 

For NDJ 2019-2020, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 2a-c) predict below-normal rainfall over most of the southern Southeast Asia. The likelihood for below-normal tercile varies among the models, with the NCEP (Figure 2a) model showing higher probabilities than the ECMWF (Figure 2b) and UK Met Office (Figure 2c) models. Overall, the models’ skill scores varies for this region, with the highest skill around the Java Sea and Papua.

There is no consistent prediction for much of northern Southeast Asia, although there is increased likelihood for above-normal rainfall for the most northern part of the region (northern parts of Laos, Myanmar, and Viet Nam). Models’ skill scores for this region are also generally low for the NDJ season, apart from over the Philippines (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office“).

Rainfall Tercile Summary of NCEP model.

Rainfall Tercile Summary of ECMWF model.

Figure 2a: Rainfall tercile summary predictions of NCEP model for NDJ 2019-2020. Figure 2b: Rainfall tercile summary predictions of ECMWF model for NDJ 2019-2020 (contains modified Copernicus C3S information).

Rainfall Tercile Summary of UK Met Office model.

Rainfall Tercile Summary of MME model.

Figure 2c: Rainfall tercile summary predictions of UK Met Office model for NDJ 2019-2020 (contains modified Copernicus C3S information). Figure 2d: Rainfall tercile summary predictions of multi-model ensemble model for NDJ 2019-2020 (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 November 2019, above-normal temperature is favoured over most parts of Southeast Asia except for the southern Maritime Continent where below- or near-normal temperature is predicted over the ocean and coastal regions.

 

For November 2019, all three models – NCEP CFSv2, ECMWF, and UK Met Office (Figures 1a-c) – consistently predict above-normal temperature conditions over most parts of the equatorial and northern Southeast Asia with stronger probabilities over regions between 0-10°N. For the southern parts of the Maritime Continent, in particular over the ocean and coastal regions, all three models predict below- or near-normal temperature conditions.

The models’ skill scores for predicting both above- and below-normal temperature terciles are generally good over equatorial parts of Southeast Asia except for the southern Maritime Continent (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 November 2019. Figure 1b: Temperature tercile summary predictions of ECMWF model for November 2019 (contains modified Copernicus C3S information).

Temperature tercile Summary of UK Met Office model.

Temperature tercile Summary of MME model.

Figure 1c: Temperature tercile summary predictions of UK Met Office model for November 2019 (contains modified Copernicus C3S information). Figure 1d: Temperature tercile summary predictions of multi-model ensemble model for November 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 NDJ 2019-2020, above-normal temperature is favoured for most parts of Southeast Asia.

 

For NDJ 2019-2020, all three models – NCEP CFSv2, ECMWF, and UK Met Office (Figures 2 a-c) – favour above-normal temperature over most parts of the region. The models are most confident over the Maritime Continent and less confident regarding the above-normal temperature over the northern part of the region.

The models’ skill for NDJ temperature prediction is good overall for the above-normal tercile (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 2a: Temperature tercile summary predictions of NCEP model for NDJ 2019-2020. Figure 2b: Temperature tercile summary predictions of ECMWF model for NDJ 2019-2020 (contains modified Copernicus C3S information).

Temperature tercile Summary of UK Met Office model.

Temperature tercile Summary of MME model.

Figure 2c: Temperature tercile summary predictions of UK Met Office model for NDJ 2019-2020 (contains modified Copernicus C3S information). Figure 2d: Temperature tercile summary predictions of multi-model ensemble model for NDJ 2019-2020 (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.