Seasonal Forecast for February-March-April 2020
Updated 5 February 2020
Summary of Outlook
The Northeast Monsoon season prevails over the ASEAN region until March/April before transitioning to Inter-monsoon conditions. During the Northeast Monsoon, the northern ASEAN region typically experiences the traditional dry season, while the rainy season prevails over the southern ASEAN region.
Above-normal temperature is expected over most parts of Southeast Asia during the Feb–Mar–Apr 2020 period. Below-normal rainfall is predicted mainly over Myanmar and the Philippines. There is higher chance of above-normal rainfall over areas south the equator, particularly around Java Sea areas and eastern archipelago of Indonesia.
With dry weather expected to persist over the northern ASEAN region, hotspot activities and hazy conditions in the Mekong sub-region are likely to persist. The risk of transboundary haze occurrence in the sub-region remains high. In the southern ASEAN region, hotspot activities are expected to remain generally subdued due to rainy weather. However, isolated hotspots with localised smoke plumes may emerge in Sumatra, Kalimantan and Malaysia during periods of drier weather in February and March.
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.
Monthly Rainfall Outlook – February 2020For February 2020, below-normal rainfall is forecasted for much of the region between 0° and 10°N. There is also an increase chance of above-normal rainfall in the northern most parts of Southeast Asia.
For February 2020, two models – NCEP CFSv2 and the ECMWF (Figures 1a, 1b) favour an increased chance of below-normal rainfall for much of the Southeast Asian region between 0° and 10°N, including northern Sumatra, Peninsular Malaysia and the Philippines, while the UK Met Office model predicts below-normal rainfall for only northern Sumatra and parts of the Philippines (Figure 1c). However, all three models, NCEP CFSv2, ECMWF, and UK Met Office are forecasting an increased probability of above-normal rainfall for the most northern parts of Southeast Asia. With regards to model skill, the region where below-normal rainfall is forecasted corresponds to the area with moderate to high skill, while the region where above-normal rainfall corresponds to one with only low to moderate skill.
Elsewhere, the models show inconsistent forecasts or have limited skill (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).
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| Figure 1a: Rainfall tercile summary predictions of NCEP model for February 2020. | Figure 1b: Rainfall tercile summary predictions of ECMWF model for February 2020 (contains modified Copernicus C3S information). |
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| Figure 1c: Rainfall tercile summary predictions of UK Met Office model for February 2020 (contains modified Copernicus C3S information). | Figure 1d: Rainfall tercile summary predictions of multi-model ensemble model for February 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.
Seasonal Rainfall Outlook – Feb-Mar-Apr 2020 (FMA 2020)For FMA 2020, below-normal rainfall is predicted for the most western and eastern parts of the northern ASEAN region, while the region just south of the equator may experience above-normal rainfall.
For FMA 2020, all three models – NCEP CFSv2, ECMWF and the UK Met Office (Figures 2a-c) – predict below-normal rainfall for the most western parts of the northern ASEAN region and the Philippines. The models also predict an increase in the probability of above-normal rainfall for regions just south of the equator. While the skill of the models is moderate to high for the Philippines and much of the Malay Peninsula, elsewhere the skill is low to moderate for this season (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office“).
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| Figure 2a: Rainfall tercile summary predictions of NCEP model for FMA 2020. | Figure 2b: Rainfall tercile summary predictions of ECMWF model for FMA 2020 (contains modified Copernicus C3S information). |
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| Figure 2c: Rainfall tercile summary predictions of UK Met Office model for FMA 2020 (contains modified Copernicus C3S information). | Figure 2d: Rainfall tercile summary predictions of multi-model ensemble model for FMA 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.
Monthly Temperature Outlook – February 2020For February 2020, above-normal temperature is favoured over most parts of Southeast Asia, apart from the most northern parts of the region.
For February 2020, 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 of Southeast Asia, apart from over Myanmar and northern Viet Nam where near-normal to below-normal temperatures are predicted.
The models’ skill for predicting the above-normal and below normal temperature tercile categories are moderate to high over most parts of Southeast Asia (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).
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| Figure 1a: Temperature tercile summary predictions of NCEP model for February 2020. | Figure 1b: Temperature tercile summary predictions of ECMWF model for February 2020 (contains modified Copernicus C3S information). |
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| Figure 1c: Temperature tercile summary predictions of UK Met Office model for February 2020 (contains modified Copernicus C3S information). | Figure 1d: Temperature tercile summary predictions of multi-model ensemble model for February 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.
Seasonal Temperature Outlook – Feb-Mar-Apr (FMA 2020)For FMA 2020, above-normal temperature is favoured over most parts of Southeast Asia.
For FMA 2020, all three models – NCEP CFSv2, ECMWF and UK Met Office (Figures 2 a-c) – favour above-normal temperature over most parts of Southeast Asia, with the highest likelihood over the central and southern parts of the region. The models’ skill for this season is moderate to high for much of Southeast Asia (see the respective sections of “Model products and verification: NCEP, ECMWF, UK Met Office”).
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| Figure 2a: Temperature tercile summary predictions of NCEP model for FMA 2020. | Figure 2b: Temperature tercile summary predictions of ECMWF model for FMA 2020 (contains modified Copernicus C3S information). |
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| Figure 2c: Temperature tercile summary predictions of UK Met Office model for FMA 2020 (contains modified Copernicus C3S information). | Figure 2d: Temperature tercile summary predictions of multi-model ensemble model for FMA 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.
Frequently Asked Questions
What is a seasonal forecast?
A seasonal forecast provides forecast information about the general weather conditions at seasonal timescales up to several months ahead. Long range predictions rely on predicting components of the atmosphere and the oceans which show variations at large spatial and temporal scales. Among these key components is the sea-surface temperature – an important indicator in the El Niño Southern Oscillation (ENSO) cycle.
Example of probabilistic long range forecast using the multi-model ensemble. For areas nearby Peninsular Malaysia, the forecast is showing a probability of 50-70% of rainfall being in the below-normal (33%) tercile range. (Source: WMO LC LRF)
To account for the chaotic nature of the atmosphere, seasonal forecast adopts a probabilistic approach and the forecast weather condition is presented as an average over an extended period of time, usually with reference to climatology.
ASMC carries out monthly seasonal forecast predictions based on various seasonal model forecasts from the leading meteorological centres, supplemented by individual assessments from respective countries in South East Asia. The skilfulness of seasonal forecast relies greatly on the performance of seasonal models, which differ from one place to another and for different seasons of the year.
Receiver operating characteristic (ROC) score of UK GloSea5 seasonal hindcast for above-normal precipitation scenario for Dec – Feb (left) and May – Jul (right) over Asia region. Higher ROC score (indicated in red) means better model skill. (Source: UK Met Office)
For example, one way to assess the seasonal model skills is to examine the ROC score. From the figures above, we can see that ROC score map differs greatly from one season to another. During the period from Dec to Feb, a high ROC score region is observed mainly over the Philippines whereas during the period from May to Jul, a high ROC score region is observed over the near equatorial region such as Peninsular Malaysia and Sumatra.