Seasonal Forecast for December-January-February 2019/2020

Updated 3 December 2019

Summary of Outlook

The transition to Northeast Monsoon season began in mid-November. During the Northeast Monsoon season, the northern ASEAN region typically experiences the traditional dry conditions, while the southern ASEAN region experiences rainy weather. To the north of the equator, the prevailing winds typically blow from the north or northeast, and blow from the west or northwest, south of the equator.

Above-normal temperature is favoured over most parts of Southeast Asia during the Dec 2019 – Feb 2020 period. For rainfall, there are no clear trends for the Dec 2019 – Feb 2020 season. The areas south of the equator may experience drier-than-normal conditions in Dec 2019.

In Dec 2019, The Mekong sub-region can expect a gradual increase of hotspot activities as the dry season sets in. Based on past year trends, an escalation of hotspot activities can be expected in late-January and February period, particularly over Thailand and Cambodia. Hotspot activities in the southern ASEAN region are expected to remain generally subdued. However, isolated hotspots may emerge in Sumatra, Kalimantan and Malaysia during periods of dry weather especially in February.

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 December 2019, below-normal rainfall is favoured over most parts of the region south of the equator. Elsewhere, predictions either are not consistent across models, or have low skill.

 

For December 2019, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 1a-c) – favour an increased chance of below-normal rainfall for parts of Southeast Asia south of the equator. This region where below-normal rainfall conditions are predicted broadly coincide with areas of moderate to high model skill. Another area with good skill for this month is around the Philippines but there is no dominant tercile predicted for this region from the models.

Elsewhere, the models show inconsistent forecasts or have limited skill (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 December 2019. Figure 1b: Rainfall tercile summary predictions of ECMWF model for December 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 December 2019 (contains modified Copernicus C3S information). Figure 1d: Rainfall tercile summary predictions of multi-model ensemble model for December 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 DJF 2019-2020, no strong signal for below- or above-normal conditions over land across Southeast Asia.

 

For DJF 2019-2020, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 2a-c) – show no consistent or strong predictions over land areas for either above- or below-normal categories. There is a slightly higher chance for below-normal conditions for land areas to the south of the equator but the skill across models for this part of the region and season is low (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 DJF 2019-2020. Figure 2b: Rainfall tercile summary predictions of ECMWF model for DJF 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 DJF 2019-2020 (contains modified Copernicus C3S information). Figure 2d: Rainfall tercile summary predictions of multi-model ensemble model for DJF 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 December 2019, above-normal temperature is favoured over most parts of Southeast Asia.

 

For December 2019, all three models – NCEP CFSv2, ECMWF, and UK Met Office (Figures 1a-c) – consistently predict a high likelihood of above-normal temperature conditions over most parts Southeast Asia, although the likelihood is less over Mainland Southeast Asia in the ECMWF and UK Met Office models.

The models’ skill for predicting above-normal temperature tercile are moderate to high over most parts of Southeast Asia except for the northern part of Mainland Southeast Asia (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 December 2019. Figure 1b: Temperature tercile summary predictions of ECMWF model for December 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 December 2019 (contains modified Copernicus C3S information). Figure 1d: Temperature tercile summary predictions of multi-model ensemble model for December 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 DJF 2019-2020, above-normal temperature is favoured over most parts of Southeast Asia.

 

For DJF 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. These areas coincide with regions of moderate to high model skill except for parts of Mainland Southeast Asia (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 DJF 2019-2020. Figure 2b: Temperature tercile summary predictions of ECMWF model for DJF 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 DJF 2019-2020 (contains modified Copernicus C3S information). Figure 2d: Temperature tercile summary predictions of multi-model ensemble model for DJF 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.