STATEMENT FROM THE TWENTY-SEVENTH SOUTHERN AFRICA REGIONAL CLIMATE OUTLOOK FORUM (SARCOF-28)
The Twenty-Eighth Southern Africa Regional Climate Outlook Forum (SARCOF-28) was held in Maputo, Mozambique from 29 to 31 January 2024 to present a consensus outlook for February- March-April (FMA), March-April-May (MAM) and April-May-June (AMJ) rainfall seasons over the SADC region. Climate forecasters from the SADC National Meteorological and/or Hydrological Services (NMHSs), the SADC Climate Services Centre (CSC) and SADC ClimSA Technical Assistance formulated this Outlook. Additional inputs were acquired from African Centre for Meteorological Application for Development (ACMAD) and Global Producing Centres (GPCs) namely, European Centre for Medium Range Weather Forecast (ECMWF), National Oceanic and Atmospheric Administration (NOAA), Beijing Climate Centre (BCC), Météo-France, Australian Bureau of Meteorology (BoM), UK Met Office (UKMO), Japan Meteorological Agency (JMA) and Korea Meteorological Agency (KMA). Inputs from International Research Institute for Climate and Society (IRI) and National Centre for Atmospheric Research (NCAR) were also used in this work.
This outlook spans the period of February to June covering the transition from summer wet season to winter dry season over most of the SADC region, “long rains’’ season in regions characterised by bi-modal rainfall (northern part of DRC and eastern part of Tanzania) and transition from summer dry season to winter wet season in the south-western tip of the continent. The Outlook is presented in overlapping three-monthly periods as follows: February-March-April (FMA), March- April-May (MAM) and April-May-June (AMJ) 2024.
SUMMARY
Bulk of the northern half of the SADC region and the southeastern parts are likely to receive normal to above-normal rainfall for most of the period from February to June 2024, except for central parts of the region and south-western parts where normal to below-normal and below-normal rainfall are expected. Above normal rainfall is expected over the north-eastern parts of the region during the March to May (MAM) 2024 period.
Normal to below-normal rainfall is expected during the April to June (AMJ) 2024 rainfall season over the north-western and south-eastern parts of the region, whilst central parts of the region are expected to receive normal to above-normal rainfall. Below normal rainfall conditions are expected to persist over the western regions of the Southern African region, mostly in Botswana, Namibia, southern Angola and south-western South Africa throughout the forecast period.
OVERVIEW OF DYNAMICAL MODELS FORECAST FROM GLOBAL PRODUCING CENTRES
The outlook presented above is broadly consistent with the forecasts generated with the multi-model ensemble of international dynamical climate forecast models presented by the Global Producing Centres mandated by World Meteorological Organization.
In summary, increased probability of above normal rainfall conditions are forecasted by the dynamical models over Tanzania and eastern DRC as well as over small island states. Below normal conditions are forecasted for all other countries within the continental part of SADC, apart from the south-eastern coast of South Africa, where normal conditions are expected. The dry anomalies are forecasted to be particularly strong over the central-western part of SADC region – southern Angola, Namibia, western Botswana, and western South Africa.
Over Madagascar – above normal conditions are forecasted for its northern part, while below normal for its southern part
These forecasts are relatively consistent across the February to June 2024 period, with minor differences between sub-seasons. Different multi-model forecasting systems agree relatively well in the overall direction of the anomalies, although their demonstrated skill varies.
The long-term mean for February-March-April rainfall shows maxima of above 600 millimetres over much of Angola, southern half of DRC, northern Zambia, Malawi, southern Tanzania central and northern Mozambique as well as Madagascar. The remainder of the region receives rainfall gradually decreasing south-westwards from about 400 millimetres in the north/ north-east towards southwest South Africa and Namibia where the mean rainfall is below 100 millimetres.
The period March-April-May shows a significant reduction in the rainfall received in most of the southern parts of the region with the northern and eastern parts remaining wet. DRC and northern Angola, Malawi, Zambia, and Mozambique show sustained rainfall patterns, while Madagascar and Tanzania show sustained rainfall in the extreme eastern coastline.
The period April- May-June shows further reduction in the rainfall received in most southern parts of the region with the north and north-eastern parts relatively wet. DRC, Madagascar, and Tanzania show sustained rainfall in the extreme north for DRC and Tanzania while for Madagascar it is mostly extreme eastern coastline.
METHODOLOGY
Using statistical analysis expert interpretation of current status of global climate system, and outputs from dynamical models run by Global Producing Centres the forecasters determined likelihoods of above-normal, normal, and below-normal rainfall for broad regions (Figures 1 to 3) for overlapping three-monthly periods i.e. February-March-April (FMA), March-April-May (MAM) and April-May-June (AMJ). Above-normal rainfall is defined as rainfall lying within the wettest third of recorded (30 years, that is, 1981-2010 mean) rainfall amounts; below-normal is defined as within the driest third of rainfall amounts and normal is the middle third, centred on the climatological median. Figure 4 shows the long-term (1981-2010) mean rainfall for February-March-April (FMA), March-April-May (MAM) and April-May-June (AMJ) seasons over SADC region.
The forecasters considered oceanic and atmospheric factors that influence the climate over the SADC region, including the El Niño-Southern Oscillation (ENSO), which is currently in its warm phase (El Niño). The ENSO is projected to remain in the El Niño phase during the forecast period. There exists an increased chance of a neutral Indian Ocean Dipole (IOD) and a positive Sub-tropical Indian Ocean Dipole (SIOD) by the end of March 2024.
NOTE: This Outlook is relevant only to seasonal (overlapping three-monthly) timescales and relatively large areas and may not fully account for all factors that influence regional and national climate variability, such as local and month-to-month variations (intra-seasonal). As such, it must not be interpreted as indicating probable rainfall anomalies at sub-regional, country-level and local spatial scales, and at shorter – sub-seasonal (monthly) time scales.
Users are strongly advised to contact the National Meteorological and Hydrological Services for interpretation of this Outlook, additional guidance, and updates.
