Angola + 2 more

Seasonal rainfall outlook for SADC countries Jan - Mar 2001


STATEMENT FROM THE FOURTH CLIMATE OUTLOOK FORUM FOR THE SOUTHERN AFRICAN REGION, 18-19 December 2000, Harare, Zimbabwe.
SUMMARY

There is a likelihood of normal to above-normal rainfall over most of the Southern African Development Community (SADC) countries for the period January-March (JFM) 2001. However, Mauritius has high probabilities of below-normal rainfall. Drought conditions are likely to continue in most parts of Tanzania.

It should be recalled that some parts of the sub-region experienced floods during 2000. In some of these areas the soil remains saturated. So, even normal rainfall conditions may lead to some risk of flooding especially in the low-lying areas.

This Outlook is relevant only for seasonal time scales and relatively large areas because the current status of seasonal forecasting allows prediction only over large areas and may not fully resolve all factors that influence regional and national climate variability. Local and month-to-month variations may occur. Any changes in the projected patterns of sea- surface temperatures and other indicators over the next few weeks would affect the outlook in some areas. The Drought Monitoring Centre, Harare (DMCH) and the National Meteorological Services (NMSs) in their respective countries therefore will provide updates of the outlooks. The users are strongly advised to contact their NMSs for interpretation of this Outlook, finer details, updates and additional guidance .

THE CLIMATE OUTLOOK FORUM

From 18 to 19 December 2000, the Fourth Southern Africa Regional Climate Outlook Forum Mid-Season Correction Meeting was convened in Harare, Zimbabwe by the DMCH to formulate consensus guidance for January-March 2001 for SADC countries. Users were active participants in the forum and raised issues pertaining to the content, interpretation and dissemination of the seasonal outlook.

METHODOLOGY

The Forum reviewed the state of the global ocean-atmospheric system and its implications for this region. Among the principal factors taken into account were the current state of the La Niña and the sea-surface temperatures over much of the tropical Indian and Atlantic Oceans. These were assessed using coupled ocean-atmosphere models, physically-based statistical models and expert interpretation. A weak La Niña has been observed and sea-surface temperatures in the equatorial Pacific Ocean are currently near average and are projected to remain around normal during the next three months.

The experts established probability distributions to indicate the likelihood of above-normal, normal and below-normal rainfall for each zone (see Map). Above-normal rainfall is defined as within the wettest 33.3% of recorded rainfall amounts in each zone; normal is defined as the middle 33.3% of the amounts while below-normal rainfall is the driest 33.3% of the recorded rainfall amounts.

RAINFALL OUTLOOK FOR JANUARY TO MARCH 2001

Zone I: (Northern half of Democratic Republic of Congo (DRC)) Greater likelihood of normal rainfall.

Zone II: (Most of Tanzania) Greater likelihood of normal to below- normal rainfall.

Zone III: (Most of Angola, northern Zambia, much of southern DRC and northern half of Malawi) Greater likelihood of above-normal to normal rainfall.

Zone IV: (Coastal Angola and coastal DRC) Greater likelihood of above-normal to normal rainfall.

Zone V: (Southern half of Zambia, extreme southern portion of DRC, northeastern half of Botswana, southern half of Malawi, Zimbabwe, northeastern Namibia, eastern portion of South Africa, Swaziland, Mozambique, southern Tanzania and Lesotho) Likelihood of normal to above-normal rainfall.

Zone VI: (Southwestern Botswana, much of central South Africa, and southeastern Namibia) Greater likelihood of normal rainfall.

Zone VII: (Mauritius) Greater likelihood of below-normal rainfall.

Zone VIII: (Coastal Namibia and west coast of South Africa) Greater likelihood of normal to above-normal rainfall.

Zone IX: (Seychelles) Greater likelihood of above-normal rainfall.

The numbers for each zone indicate the probabilities for rainfall in each of the three categories, above-normal, normal, and below-normal. The top number indicates the probability of rainfall occurring in the above-normal category, the middle number is for the normal, and the bottom for the below-normal for JFM 2001. In the case of northern DRC (Zone I) for example, there is 30% probability for rainfall occurring in the above-normal category; a 45% probability for rainfall in the normal category; and a 25% probability for the below-normal category. It is emphasized that boundaries between zones should be considered as transition zones.

CONTRIBUTORS

The Fourth Southern Africa Regional Climate Outlook Forum mid-season correction meeting was organized by DMCH in conjunction with Zimbabwe Meteorological Services. Contributors to this consensus forecast included representatives of Meteorological Services from all fourteen SADC countries (Angola, Botswana, Democratic Republic of Congo, Lesotho, Malawi, Mauritius, Mozambique, Namibia, Tanzania, Seychelles, Swaziland, South Africa, Zambia and Zimbabwe). There were also climate scientists and other experts from national, regional and international institutions and organizations (DMCH, International Research Institute for Climate Prediction, SADC Regional Remote Sensing Unit, universities and research institutes). Other international institutions also provided additional input. Users and media contributed greatly in the production of the statement.

©2000, Drought Monitoring Center - Harare. - All rights reserved.