The IRI has prepared this experimental Climate Outlook for Africa for October 2001 - March 2002. Of relevance in the preparation of this outlook is the prediction of near-average to slightly warmer than average conditions in the eastern equatorial Pacific for the next 6 to 9 months. Currently the sea surface temperatures (SSTs) across much of the eastern and central equatorial are near their long-term average (SSTs), although slightly lower than average SSTs have developed along the immediate western coast of South America and warmer than average SSTs persist in the extreme western part of the basin. Near neutral equatorial Pacific SST conditions are in effect for the first season of the forecast, October-December 2001, November-January 2002, December-February 2002, while during the second season, January-March 2002, they are expected to be slightly above average. The warmer than average SSTs that continue to dominate much of the Indian Ocean are expected to decrease slowly through the forecast period. The area of above-average temperature in the tropical south Atlantic Ocean is expected to persist through at least the first half of the forecast period.

This Outlook was prepared using the following procedures and information:

A) Coupled ocean-atmosphere model predictions of tropical Pacific SST covering the forecast period. Particularly heavy weighting has been given to predictions from the coupled model operated by the NOAA National Centers for Environmental Prediction, Climate Modeling Branch. This model suggests a continuation of near-average conditions during the first forecast season. The forecast for near-neutral conditions is consistent with some, but not all, numerical and statistical forecasts of central and eastern Pacific SSTs.

B) Forecasts of the tropical Indian ocean using a statistical model developed by the IRI.

C) Global atmospheric general circulation model (GCM) predictions of the atmospheric response to the present and predicted sea-surface temperature patterns.

D) Other sources of information include NASA's Seasonal to Interannual Prediction Project (GSFC-NASA).

The procedures, models, and data used to derive this Climate Outlook may be somewhat different from those used by the national meteorological services in the region. Thus, this product may differ from the official forecasts issued in those areas. The Climate Outlook for October 2001 - March 2002 is dependent on the accuracy of the SST predictions. For the tropical Pacific, these predictions can be expected to provide useful information, but there is some uncertainty concerning the evolution of SSTs. Spread (variation) in global SST predictions is a source of uncertainty in the Outlook provided here. In particular, the forecasts for the tropical Indian and Atlantic oceans have been an important influence on the forecasts over Africa. Note that even if perfectly accurate SST forecasts were possible, there would still be uncertainty in the climate forecast due to chaotic internal variability of the atmosphere. These uncertainties are reflected in the probabilities given in the forecast.

It is stressed that the current status of seasonal-to-interannual climate forecasting allows prediction of spatial and temporal averages, and does not fully account for all factors that influence regional and national climate variability. This Outlook is relevant only to seasonal time scales and relatively large areas; local variations should be expected, and variations within the 3-month period should also be expected. For further information concerning this and other guidance products, users are strongly advised to contact their National Meteorological Services.

This Outlook covers four seasons: October-December 2001, November-January 2002, December-February 2002 and January-March 2002. Maps are given showing tercile probabilities of precipitation and temperature. The maps for precipitation indicate the probabilities that the seasonal precipitation will fall into the wettest third of the years (top number), the middle third of the years (middle number), or the driest third of the years (bottom number). The color shading indicates the probability of the most dominant tercile -- that is, the tercile having the highest forecast probability. The color bar alongside the map defines these dominant tercile probability levels. The upper side of the color bar shows the colors used for increasingly strong probabilities when the dominant tercile is the above-normal tercile, while the lower side shows likewise for the below-normal tercile. The gray color indicates an enhanced probability for the near-normal tercile (nearly always limited to 40%). As before, numbers and their associated histograms show the probabilities of the three terciles. In areas with lots of spatial detail, there may not be sufficient room on the map, to allow histograms for each region. In those cases, some idea of the probabilities may be gained from the color alone. A qualitative outlook of climatology ("C") indicates that there is no basis for favoring any particular category. Areas that are marked by "D" represent regions experiencing their dry season (less than 15% of annual precipitation) and for which less than 5 cm of precipitation typically occurs over the season. Otherwise, for example, in the case of eastern Ethiopia and parts of Somalia in October-December 2001 (Map A), there is a 20% probability that the precipitation will be in the wettest third of the years, a 35% chance it will be in the near-normal third of the years, and a 45% chance that the precipitation will be in the driest third of the years.

Maps of temperature show expected probabilities that the seasonal temperatures will fall into the warmest third of the years, the middle third of the years, or the coldest third of the years (Map A). The numbers for each region on the temperature maps indicate the probabilities of temperatures to fall in each of the three categories, above-, near-, and below-normal.

An additional precipitation map is provided for the first season indicating probabilities for extreme precipitation anomalies. Extremes are defined as anomalies that fall within the top and bottom 15th percentile of the observed records. A priori, there is a 15% probability of being within the extremely wet category, and a 15% probability of being within the extremely dry category, leaving a 70% probability that the precipitation will not be extreme. The maps indicate areas of increased risk of extreme precipitation totals. Three levels of increased risk are defined: slightly enhanced risk, enhanced risk, and greatly enhanced risk. For slightly enhanced risk, there is a 25-40% probability that precipitation will be within the indicated extreme, i.e. wet or dry. This represents an approximate doubling of the climatological risk. For enhanced risk, there is a 40-50% probability that precipitation will be within the indicated extreme. This represents an approximate tripling of the climatological risk. For greatly enhanced risk, the probability that precipitation will be within the indicated extreme exceeds 50%, i.e. the indicated extreme is the most likely outcome. A similar map is provided in the first season indicating probabilities of extreme temperature anomalies.

Boundaries between sub-regions should be considered as transition zones, and their location considered to be only qualitatively correct.

October-November-December 2001:

Slightly enhanced probabilities for near normal precipitation (30%-40%-30%) are forecast for a region including parts of Uganda, Kenya, Tanzania and Rwanda.

An enhanced probability for below normal precipitation (45%-30%-25%) is forecast for eastern and central Ethiopia, northern Kenya and much of Somalia, surrounded by more weakly enhanced probabilities for below normal precipitation in additional portions of these same countries as well as parts of Sudan, Chad, Tanzania, Mozambique and Madagascar.

An enhanced probability for below normal precipitation (45%-30%-25%) is forecast for Zambia and portions of adjacent countries, surrounded by more weakly enhanced probabilities for below normal precipitation in additional portions of these same countries and others in south-central Africa.

A greatly enhanced probability for below normal precipitation (50%-30%-20%) is forecast for western Gabon, surrounded by more weakly enhanced probabilities for below normal precipitation in most of the remainder of Gabon, and all or part of Nigeria, Cameroon, Equatorial Guinea, Congo, Zaire and Angola.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for northwestern South Africa, southern Botswana and southeastern Namibia.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for the southern coast of South Africa.

A very greatly enhanced probability for above normal temperature (10%-25%-65%) is forecast for Central African Republic, Democratic Republic of Congo and Angola, surrounded by more weakly enhanced probabilities for above normal temperature in much of the remainder of central and southern Africa. Some of this larger region has probabilities for above normal temperature nearly as high as the core area, as for example southern Chad (10%-30%-60%).

A very greatly enhanced probability for above normal temperature (10%-30%-60%) is forecast for part of Mauritania and Mali, surrounded by more weakly enhanced probabilities for above normal temperature in much of the remainder of western and west-central Africa.

A greatly enhanced probability for above normal temperature (15%-30%-55%) is forecast for Eritrea (formerly northern Ethiopia) and a tiny part of northeastern Sudan, surrounded by more weakly enhanced probabilities for above normal temperature in much of the Greater Horn of Africa.

An enhanced probability for above normal temperature (15%-40%-45%) is forecast for the Madeire Islands and the Canary Islands.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for central Madagascar.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for portions of northern and north-central Africa.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for portions of Yemen and Somalia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for a significant portion of the Gulf of Guinea region, extending southeward along the Atlantic coast of central-southern Africa.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for Seychelles Islands, as well as portions of Tanzania, Mozambique, Madagascar and Malawi.

Slightly enhanced probabilities for near normal temperature (30%-40%-30%) are forecast for southwestern Madagascar, as well as southeastern Mozambique.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the Mascarene Islands.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the southwestern tip of South Africa.

November-December-January 2001-2002:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for much of Niger and northern Nigeria.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for parts of Mauritania, Maui, Guinea, Senegal and Burkina Faso.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for parts of Sudan, Ethiopia, Central African Republic and Democratic Republic of the Congo.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for southern Somalia, southern Kenya, and part of Tanzania.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for the Democratic Republic of Congo, and Congo.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for Ascension Island.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for Zimbabwe and parts of immediately adjacent countries, particularly southern Mozambique.

Slightly enhanced probabilities for near normal precipitation (30%-40%-30%) are forecast for parts of Tanzania and Mozambique.

Slightly enhanced probabilities for near normal precipitation (35%-40%-25%) are forecast for central and southwestern South Africa.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for South Yemen and Saudi Arabia.

An enhanced probability for below normal precipitation (45%-30%-25%) is forecast for Sao Tome and Principe, surrounded by more weakly enhanced probabilities for below normal precipitation in parts or all of Benin, Togo, Nigeria, Cameroon and Gabon.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for southern Ethiopia, northern Kenya and small parts of adjacent countries.

Slightly enhanced probabilities for below normal and near normal precipitation (40%-40%-20%) are forecast for central and northeastern Madagascar.

A very greatly enhanced probability for above normal temperature (10%-30%-60%) is forecast in three separate regions of Africa, including all or parts of Mali, Burkina Faso, Niger, Benin, Nigeria, Chad, Sudan, Mauritania, Togo, Central African Republic, Angola and Zambia. These three regions are surrounded by more weakly enhanced probabilities for above normal temperature in much of the remainder of Africa, particularly the central, northeastern and south-central portions.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Morocco, Algeria and Western Sahara.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for part of Tunisia and Libya.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for northern Egypt.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for all or part of Gambia, Senegal, Guineabissau, Guinea, Sierra Leone, Liberia, Cote D'Ivoire and Ghana.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for small portions of Gabon, Congo, Angola, and Democratic Republic of Congo.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for all or part of southeastern Africa, such as Tanzania, Zambia, Malawi, Mozambique, Zimbabwe, South Africa and Botswana.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for part of Namibia and southern Angola.

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for eastern Mozambique and central and southern Madagascar.

December-January-February 2001-2002:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for parts of Niger, Chad, Nigeria, Cameroon and Sudan.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for all or part of Mali, Burkina Faso, Guinea, Cote D'Ivoire, Ghana and Liberia.

An enhanced probability for above normal precipitation (20%-35%-45%) is forecast for the Seychelles Islands.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for parts of Anglola, Zambia, Botswana and Namibia.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for the Mascarene Islands.

Slightly enhanced probabilities for near normal precipitation (25%-40%-35%) are forecast for parts of Kenya, Ethiopia, Somalia, Kenya, Uganda, Sudan and Tanzania.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for parts of Algeria, Niger and Mali.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for all or parts of Saudi Arabia, Kenya, Somalia, Djibouti, Yemen, Ethiopia, Sudan and Eritrea.

A greatly enhanced probability for above normal temperature (15%-30%-55%) is forecast for part or all of Mauritania, Mali, Senegal, Guinea and Burkina Faso, surrounded by more weakly enhanced probabilities for above normal temperature in much of the remainder of western Africa, extending to eastern Africa.

A greatly enhanced probability for above normal temperature (20%-30%-50%) is forecast for part or all of Sudan, Ethiopia, Eritrea and Djibouti, surrounded by more weakly enhanced probabilities for above normal temperature in adjoining sections of eastern Africa, extending to western Africa.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for parts of Kenya, Tanzania, Uganda and Rwanda.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for much of northwestern Africa.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for parts of Morocco and Algeria.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the Madeire Islands, Canary Islands, Western Sahara and Morocco.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for northeast Somalia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Sierra Leone and Liberia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35% and 35%-40%-25%) are forecast for most of the southern one-third of the African continent.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Sudan and Ethiopia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the Seychelles Islands.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the Mascarene Islands.

January-February-March  2001-2002:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for a small part of Saudi Arabia.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for portions of Niger and Chad.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for parts of Democratic Republic of Congo, Uganda, Sudan, and Rwanda.

Slightly enhanced probabilities for near normal and above normal precipitation (20%-40%-40%) are forecast for parts of Kenya, Somalia and Tanzania.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for parts of Angola and Namibia.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for parts of Zambia and Zimbabwe.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for the Mascarene Islands.

Slightly enhanced probabilities for near normal precipitation (25%-40%-35%) are forecast for southern Somalia as well as parts of Kenya and Tanzania.

Slightly enhanced probabilities for near normal precipitation (25%-40%-35%) are forecast for small portions of Angola and Namibia.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for portions of Mauritania, Mali and Guinea.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for small portions of Mazambique and South Africa.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for portions of Mali, Mauritania, Guinea, Burkina Faso, Cote D'Ivoire, Ghana, Togo, Niger, Benin, Nigeria, Cameroon, and Algeria.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for portions of Sudan and Ethiopia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35% and 35%-40%-25%) are forecast for some portions of the northern and western coasts of Africa.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Saudi Arabia, Yemen, Sudan and Ethiopia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35% and 35%-40%-25%) are forecast for most of the southern one-third of Africa, including the Guinea Coast.

OBSERVED CLIMATOLOGY DATA for Oct-Nov-Dec, Nov-Dec-Jan, Dec-Jan-Feb and Jan-Feb-Mar

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