The IRI has prepared this experimental Climate Outlook for Africa for September 2001 - February 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 Pacific are near their long-term average, with locally warm anomalies near the dateline (SSTs), although slightly lower than average SSTs exist in the far eastern equatorial Pacific and warmer than average SSTs persist in the extreme western part of the basin. Near neutral (<0.5C) equatorial Pacific SST conditions are in effect for the first half of the forecast period, September-November 2001, October-December 2001, while during the second half, November-December 2001-January 2002, December 2001-February 2002, they are expected to be slightly above average (approximately 0.5C). 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 Atlantic Ocean has weakened over the last couple months and is predicted to weaken further through 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 September 2001 - February 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: September-November 2001, October-December 2001, November-December 2001-January 2002 and December 2001-February 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 right side of the color bar shows the colors used for increasingly strong probabilities when the dominant tercile is the above-normal tercile, while the left 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 northern Chad in September-November 2001 (Map A), there is a 40% probability that the precipitation will be in the wettest third of the years, a 30% chance it will be in the near-normal third of the years, and a 30% 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.

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

September-October-November 2001:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

An enhanced probability for below normal precipitation (45%-35%-20%)is forecast for portions of southwestern Kenya and northern Tanzania, surrounded by more weakly enhanced probabilities for below normal precipitation in much of the remainder of those countries as well as in Uganda, Burgundi and Rwanda.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%)are forecast for northern Chad and southern Libya.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%)are forecast for Sierra Leone and western Liberia.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%)are forecast for northeastern Sudan and northern Ethiopia.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30% and 40%-35%-25%) are forecast for western Angola, northern Namibia, western Gabon, western Democratic Republic of the Congo, and southwestern Congo.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for mainly the coastal portions of Ghana, Cote D'ivoire, and Liberia.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for northeastern Madagascar.

The following regions of enhanced probabilities of temperature anomalies are indicated:

A very greatly enhanced probability for above normal temperature (10%-30%-60%)is forecast for the Democratic Republic of the Congo, surrounded by various degrees of more weakly enhanced probabilities for above normal temperature in much of Africa, particularly the central portion. Additional countries having the most enhanced probabilities are Central African Republic, southern Chad, eastrn Sudan, western Ethiopia, Rwanda, Burundi, western Tanzania, eastern Cameroon, southern Mali, northern Burkina Faso, and western Niger.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for northern Algeria, surrounded by more weakly enhanced probabilities for above normal temperature in additional portions of Algeria and much of Morocco.

An enhanced probability for below normal temperature (45%-35%-20%)is forecast for the Mascarene Islands (east of Madagascar), surrounded by more weakly enhanced probabilities for below normal temperature in the surrounding area, such as Tromelin Island to the north.

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

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for Tunisia, mainly northeastern Algeria, and northwestern Libya.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Guinea, Guinea-Bissau, Gambia, southern Senegal, Sierra Leone, western and southern Liberia, southern Cote D'Ivoire, and southwestern Ghana.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for Sao Tome and Principe, and western Gabon.

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

October-November-December 2001:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

An enhanced probability for above normal precipitation (20%-35%-45%) is forecast for southern Somalia, surrounded by more weakly enhanced probabilities for above normal precipitation in most of the remainder of the southern and part of central Somalia, southeastern Ethiopia, and extreme northeastern Kenya.

An enhanced probability for below normal precipitation (45%-35%-20%)is forecast for mainly Kenya, and portions of adjacent countries. A separate but associated regions is forecast likewise, centered over southwestern Angola, western Zambia, northern Botswana, and the Namibia "panhandle". Surrounding and connecting these two regions is a broader area having more weakly enhanced probabilities for above normal precipitation, including remaining portions of the above countries as well as portions of adjacent countries such as Malawi, Rwanda, Burundi, Democratc Pepublic of the Congo, Uganda and Kenya.

An enhanced probability for below normal precipitation (45%-30%-25%) is forecast for Tromelin Island, surrounded by more weakly enhanced probabilities for enhanced probabilities for above normal precipitation (25%-35%-40%)are forecast for northeastern South Africa, southern Zimbabwe, southern Mozambique and eastern Botswana.

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

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%)are forecast for western portions of the countries of Senegal, Gambia, Mauritania and Bissau.

A slightly enhanced probability for below normal precipitation (40%-35%-25%) is forecast for northeastern Madagascar.

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

The following regions of enhanced probabilities of temperature anomalies are indicated:

A very greatly enhanced probability for above normal temperature (10%-30%-60%)is forecast for a small southwestern portion of Democratic Republic of the Congo and adjacent northeastern Angola, surrounded by various degrees of more weakly enhanced probabilities for above normal temperature in much of Africa, particularly the central portion. Additional countries having the most enhanced probabilities are western Tanzania, Central African Republic, southern Chad, northern Botswana, southern Saudi Arabia, northern Ethiopia, Burundi, all except northern Mali, northern Burkina Faso, and southern Mauritania.

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

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for southwestern Egypt, southeastern Libya and northwestern Sudan.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for southeastern Algeria and small portions of adjacent Niger and Libya.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for western portions of the countries of Senegal, Mauritania, Bissau, Gambia, and Sierra Leone.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for southern portions of the countries of Benin, Ghana, and Cote D'Ivoire, and western coastal portions of Gabon and Equatorial Guinea.

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

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for the Mascarene Islands, east of Madagascar.

November-December 2001-January 2002:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

An enhanced probability for below normal precipitation (45%-35%-20%)is forecast for part of Kenya and a tiny portion of northern Tanzania, surrounded by more weakly enhanced probabilities for below normal precipitation in most of the remainder of Tanzania, northern Zambia, northern Malawi, northeastern Mozambique, most of Burundi and Rwanda, eastern Uganda, and small parts of southern Sudan and Eithiopia.

An enhanced probability for below normal precipitation (45%-40%-15%) is forecast for Cargados Carajos Bank, east of Madagascar, surrounded by more weakly enhanced probabilities for below normal precipitation in the Mascarene Islands and in eastern and northeastern Madagascar.

Slightly enhanced probabilities for near normal precipitation (30%-40%-30% and 25%-40%-35%) are forecast for part of South Africa and extreme southern Botswana.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%)are forecast for parts of Somalia and eastern Ethiopia.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%)are forecast for the western third of Central African Republic, northern Republic of the Congo, and parts of Gabon, Cameroon, Equatorial Guinea, and Chad.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%)are forecast for parts of Botswana, Zimbabwe, northern South Africa, southern Mazambique, and Swaziland.

The following regions of enhanced probabilities of temperature anomalies are indicated:

A very greatly enhanced probability for above normal temperature (10%-30%-60%)is forecast for southern Saudi Arabia, the southern Red Sea, and a tiny portion of northeastern Ethiopia. A separate but associated region of greatly enhanced probability for above normal temperature (55%-30%-15%) is centered in the southern Democratic Republic of the Congo, northern Zambia and eastern Angola. These two regions are surrounded and connected by more weakly enhanced probabilities for above normal temperature in much of Africa. Additional countries having the most enhanced probabilities are western Tanzania, northern Democratic Republic of the Congo, Central African Republic, southern Chad, southern Sudan, northern Somalia, northern Botswana, northern Ethiopia, Burundi, Rwanda, southern Uganda, part of Mauritania and part of Mali.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%)are forecast for western Algeria and southern Morocco.

Slightly enhanced probabilities for near normal temperature (30%-40%-30%)are forecast for northern Algeria and part of Tunisia.

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

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the western portions of the countries of Senegal, Mauritania, Bissau and Gambia.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the coastal portions of Cote D'ivoire, Liberia, Benin, Togo, and Ghana.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Cameroon, Gabon, and Republic of the Congo.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for northern Mozambique, southern Tanzania, eastern Zambia and northern Zimbabwe.

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

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for the Mascarene Islands, and northern Madagascar.

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for part of South Africa and Lesotho.

Slightly enhanced probabilities for below normal temperature (40%-40%-20%)are forecast for part of southern Mozambique.

December 2001-January-February 2002:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

An enhanced probability for above normal precipitation (20%-35%-45%) is forecast for southern Burkina Faso, most of Cote D'ivoire, eastern Guinea and northwestern Ghana, surrounded by more weakly enhanced probabilities for above normal precipitation in much of the remainder of the Guinea Coast region and the Sahel.

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

Slightly enhanced probabilities for near normal precipitation (30%-40%-30%)are forecast for part of northwestern Democratic Republic of the Congo, northern Republic of the Congo, southeastern Cameroon and northeastern Gabon.

Slightly enhanced probabilities for near normal precipitation (35%-40%-25%) are forecast for part of Uganda, western and southern Kenya, and northern Tanzania.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%)are forecast for Ascension Island, well southwest of the Guinea Coast.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%)are forecast for southern Mozambique, most of Zimbabwe, southwestern Zambia, eastern Botswana, northeasternSouth Africa and Swaziland.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for western Tanzania, Burundi, northern Zambia, and part of eastern Democratic Republic of the Congo.

The following regions of enhanced probabilities of temperature anomalies are indicated:

An enhanced probability for above normal temperature (25%-30%-45%) is forecast for southern Mauritania, western Mali, western Senegal and northern Guinea, surrounded by more weakly enhanced probabilities for above normal temperature in additional portions of all of these countries as well as in all or parts of Liberia, Cote D'Ivoire, Burkina Faso, Guinea Bissau, and Niger.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for southern Saudi Arabia, northeastern Ethiopia, northern Somalia, and the southern Red Sea, surrounded by more weakly enhanced probabilities for above normal temperature in additional portions of those same countries, as well as much of central Sudan.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for portions of Angola, surrounded by more weakly enhanced probabilities for above normal temperature in most of the remainder of Angola, northern Namibia, northern Botswana, western Zimbabwe, southwestern Democratic Republic of the Congo, southern Republic of the Congo, and southern Gabon.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the coast of western Sahara.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for parts of Sierra Leone, Cote D'ivoire, Liberia, Guinea, Ghana, and Togo.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for a broad area in central and southern Africa, ranging from southern Cameroon in the northwest, to the coast of Tanzania in the east, to Botswana in the south, and including many of the countries in between those.

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

Slightly enhanced probabilities for above normal temperature (30%-30%-40%)are forecast for part of Morocco and part of western Algeria.

Slightly enhanced probabilities for above normal temperature (30%-30%-40%)are forecast for Ascension Island, well to the southwest of the Guinea Coast.

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

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for the Mascarene Islands off the coast of Madagascar.

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

CLIMATOLOGICAL AVERAGE: Temperature Precipitation

TERCILE THRESHOLDS (33%-ile & 67%-ile): Temperature Precipitation

EXTREME THRESHOLDS (15%-ile & 85 %-ile): Temperature Precipitation

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