Seasonal Forecast for March – May 2024

Updated 4 Mar 2024

The Northeast Monsoon which prevailed in recent months generally persists until late March. During this period, the northern ASEAN region remains dry, while showers continue in the southern ASEAN region. The prevailing low-level northwesterly to northeasterly winds over the ASEAN region typically weaken and become light and variable in late March. This change signals the transition from the Northeast Monsoon to the inter-monsoon period which is expected to extend to May.

For March to May (MAM) 2024 period, models predict an increased chance of above-normal rainfall over the southern ASEAN region and below-normal rainfall over the northern ASEAN region. The El Niño conditions are predicted to continue weakening, likely returning to neutral during April-May 2024. The Indian Ocean Dipole (IOD) is neutral, and most models predict the neutral IOD conditions to persist for the next three months. Above-normal temperature is predicted for the ASEAN region for MAM 2024. El Niño tends to bring drier and warmer conditions to much of the region at this time of year.

With below normal rainfall forecast over most parts of the Mekong sub-region for the MAM 2024 period, the hotspot and smoke haze situation may escalate further from March to May. Prolonged drier conditions in the northern ASEAN region, specifically the Mekong sub-region, can lead to an increased risk of transboundary smoke haze. Over the southern ASEAN region, wet weather is expected to continue and hotspot activity is expected to remain subdued during MAM 2024, although isolated hotspots with localised smoke plumes may occur during brief dry periods.

The qualitative outlook is assessed for the region in general and based on the latest runs from models provided by the SEA RCC-Network LRF node. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

For March 2024, above-normal rainfall is predicted for much of the southern ASEAN region and below-normal rainfall is predicted over the northeastern Maritime Continent.

 

For March 2024, above-normal rainfall is predicted for much of the southern ASEAN region based on the multi-model ensemble (Figure 4). The UK Met Office model (Figure 3) shows the highest confidence for above-normal rainfall over the central Maritime Continent, while the NCEP model (Figure 1) shows the largest extent of above-normal rainfall. For above-normal rainfall over the southern ASEAN region, models’ skill is moderate to good for the ECMWF and UK Met Office models, and low to moderate for the NCEP model.

Below-normal rainfall is predicted over the northeastern Maritime Continent, based on the multi-model ensemble (Figure 4). The ECMWF (Figure 2) and UK Met Office (Figure 3) models show the highest likelihood for below-normal rainfall over the Philippines and northern Borneo, while the NCEP model (Figure 1) has a lower chance of below-normal rainfall, primarily around the Philippines. The models’ skill is good for the northeastern Maritime Continent.

For Mainland Southeast Asia, all three models (Figures 1-3) predict below-normal rainfall over the western parts of Mainland Southeast Asia, but with low confidence and disagreement on the spatial extent. While the ECMWF model (Figure 2) predicts below-normal rainfall over parts of southern and eastern Mainland Southeast Asia, the NCEP and UK Met Office models (Figures 1 and 3) predict near-normal rainfall or no dominant tercile. The models’ skill is generally low to moderate for Mainland Southeast Asia.

Figure 1: Rainfall tercile summary predictions of NCEP model for March 2024 (contains modified Copernicus C3S information). Figure 2: Rainfall tercile summary predictions of ECMWF model for March 2024 (contains modified Copernicus C3S information).

Figure 3: Rainfall tercile summary predictions of UK Met Office model for March 2024 (contains modified Copernicus C3S information). Figure 4: Rainfall tercile summary predictions of multi-model ensemble model for March 2024 (contains modified Copernicus C3S information).

Figure 5: Average climatological rainfall’s lower tercile boundary for March based on CHIRPS (reference period: 1991-2020). Figure 6: Average climatological rainfall’s upper tercile boundary for March based on CHIRPS (reference period: 1991-2020).

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 MAM 2024, above-normal rainfall is predicted for the southern ASEAN region with below-normal rainfall for the northern ASEAN region.

 

For MAM 2024, above-normal rainfall is predicted for the southern ASEAN region based on the multi-model ensemble (Figure 4). The ECMWF model (Figure 2) shows the highest confidence of above-normal rainfall over the southern ASEAN region, followed by the NCEP model (Figure 1) and then the UK Met Office model (Figure 3). Models’ skill is moderate to good for above-normal rainfall over the southern ASEAN region.

Below-normal rainfall is predicted over the northern ASEAN region, based on the multi-model ensemble (Figure 4). Over the Philippines, the ECMWF (Figure 2) model shows high confidence for below-normal rainfall, followed by the UK Met Office Model (Figure 2), and then the NCEP model (Figure 1) showing below- to near-normal rainfall over the region. Over Mainland Southeast Asia, the NCEP and ECMWF models show below-normal rainfall over much of the region, while the UK Met Office model shows near-normal rainfall. The models’ skill for below-normal rainfall is relatively good over Philippines and moderate to good over Mainland Southeast Asia.

Figure 1: Rainfall tercile summary predictions of NCEP model for MAM 2024 (contains modified Copernicus C3S information). Figure 2: Rainfall tercile summary predictions of ECMWF model for MAM 2024 (contains modified Copernicus C3S information).

Figure 3: Rainfall tercile summary predictions of UK Met Office model for MAM 2024 (contains modified Copernicus C3S information). Figure 4: Rainfall tercile summary predictions of multi-model ensemble model for MAM 2024 (contains modified Copernicus C3S information).

Figure 5: Average climatological rainfall’s lower tercile boundary for MAM based on CHIRPS (reference period: 1991-2020). Figure 6: Average climatological rainfall’s upper tercile boundary for MAM based on CHIRPS (reference period: 1991-2020).

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 March 2024, above-normal temperature is predicted over the ASEAN region.

 

For March 2024, above-normal temperature is predicted over the ASEAN region based on the multi-model ensemble (Figure 4). All three models agree with high confidence on above-normal temperature over the Maritime Continent and most of Mainland Southeast Asia. Models’ skill for predicting above-normal temperature over the Maritime Continent is relatively good, and moderate to good over Mainland Southeast Asia.

Figure 1: Temperature tercile summary predictions of NCEP model for March 2024 (contains modified Copernicus C3S information). Figure 2: Temperature tercile summary predictions of ECMWF model for March 2024 (contains modified Copernicus C3S information).

Figure 3: Temperature tercile summary predictions of UK Met Office model for March 2024 (contains modified Copernicus C3S information). Figure 4: Temperature tercile summary predictions of multi-model ensemble model for March 2024 (contains modified Copernicus C3S information).

Figure 5: Average climatological temperature for March based on ERA5 (reference period: 1991-2020).

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 MAM 2024, the models predict an increased chance of above-normal temperature over the ASEAN region.

 

For MAM 2024, above-normal temperature is predicted over the ASEAN region based on the multi-model ensemble (Figure 4). All three models agree with high confidence on above-normal temperature over most of the region. Models’ skill for predicting above-normal temperature for the ASEAN region is relatively good over most of the region, except of parts over northwestern Mainland Southeast Asia where the skill is moderate.

Figure 1: Temperature tercile summary predictions of NCEP model for MAM 2024 (contains modified Copernicus C3S information). Figure 2: Temperature tercile summary predictions of ECMWF model for MAM 2024 (contains modified Copernicus C3S information).

Figure 3: Temperature tercile summary predictions of UK Met Office model for MAM 2024 (contains modified Copernicus C3S information). Figure 4: Temperature tercile summary predictions of multi-model ensemble model for MAM 2024 (contains modified Copernicus C3S information).

Figure 5: Average climatological temperature for MAM based on ERA5 (reference period: 1991-2020).

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.