Weekly Introduction
Update of Seasonal Outlooks at One-Month Lead:
Aug-Oct 2005 Forecasts
Gulf of Guinea Region:
Climatology is expected across the domain, except locally over northwestern Cote d’Ivoire.
Northern Horn of Africa:
There is a slight tilt in the odds favoring below normal rainfall over portions of central Sudan, including the Darfur region, and locally over northwestern Ethiopia. There is a slight tilt in the odds favoring above normal rainfall locally over north central Ethiopia.
Sahel:
There is a low to moderate tilt in the odds favoring below normal rainfall over portions of southeastern Senegal, western and central Mali, and central Mauritania. There is a slight tilt in the odds favoring above normal rainfall locally over northeastern Mali.
Weather Hazards Assessment Graphic:
1. Rainfall during the March -- May 2005 rainy season was well below normal across southern Somalia, eastern Kenya and some parts of interior northeastern Tanzania. Rainfall totals for the period were only 40 to 70 percent of the long term average. This has resulted in deficits that range from 50 mm in some of the arid lowlands to over 400 mm in the mountains of southern Kenya. The lack of rainfall has likely reduced water supplies, degraded pastures, reduced crop production and resulted in crop failures. Along the north Kenya coast and far southern Somalia coast, heavy rains have managed to break the drought. However, conditions remain dry across the interior. Showers are possible along the coast during the period. Dry conditions are expected to persist away from the coast.
2. Below normal rainfall and above normal temperatures in recent years has lead to a decline in the water level on Lake Victoria. During late 2004 and early 2005, Lake Victoria’s water levels were more than three quarters of a meter below normal. This is the lowest the lake has been in over ten years. The low water levels reduced inflow to the Nile River and reduced hydroelectric power generation in southern Uganda. The recent rainy season has helped to raise the water levels marginally, however a recent satellite pass indicates that the water level is still six tenths of a meter below normal. As a result, reduced inflow into the Nile and the potential for reduced hydroelectric power generation will continue for the foreseeable future.
3. The rainy season ended 4 to 6 weeks early across much of Gabon and Equatorial Guinea. The early end to the rains resulted in moisture deficits of 150 to 400 mm and may have stressed crops that were not yet fully developed in May and early June. Showers are possible across Equatorial Guinea and far northern Gabon, however most of the region is expected to remain dry during the period. The rainy season typically begins in September across this part of Africa, with the heaviest rains of the year usually falling during the month of October.
4. Poor rainfall during the 2004-05 rainy season has resulted in the development of severe drought across southern Malawi, eastern Zimbabwe, a large portion of Mozambique and the northeastern corner of South Africa. Rainfall amounts for the season, which runs from November to April, were only 40 to 70 percent of normal. The moisture deficits of 200 to 600+ mm caused crop production losses, crop failures, degraded pastures and reduced water supplies. Seasonably dry conditions are expected during the period across southeastern Africa.
5. During the last few weeks of June and first few weeks of July, rainfall has been erratic and lighter than normal across the southern-most part of the Ethiopian Highlands and the southern foothills of the Ahmar Mountains. These erratic rains may result in crop stress across parts of central Oromiya and eastern SNNPR. However, some parts of the area have received adequate rainfall. Rain chances are expected to improve during the period. An increase in rainfall will benefit crops and pastures in the region.
6. After soaking rains during the first ten days of July, somewhat drier conditions are expected across northern portions of West Darfur in Sudan and Biltine prefecture in Chad. However, heavy rain will continue to be a problem across Ouaddai prefecture in Chad and southern portions of West Darfur. The heavy rains will hamper overland travel in the region and disrupt the movement of humanitarian aid, fuel and supplies to IDP and refugee camps. In addition, the heavy rains will result in areas of standing water which raise concerns over sanitation and the spread of water/vector borne disease in the vicinity of the camps. The occurrence of heavy rain will also add to the overall stress and misery of those in the camps. However, the abundant rainfall will be beneficial to local farmers, pastures and will increase water supplies in the region.
7. Little, if any rain has fallen across southeastern parts of Cote D’Ivoire and southwestern Ghana during the first few weeks of July. The dry spell has stressed immature crops in the area. However, a tropical wave produced abundant rainfall across interior sections. This helped to boost moisture and eased moisture stress. However, areas near the coast remained dry. Showers are expected across the region, which may ease short term moisture deficits and crop stress. This would provide sufficient moisture for maturing crops before the mini dry season, which typically sets in during the final weeks of July and lasts through August.
Questions or comments about this product may be directed to Alvin.Miller@noaa.gov or 1-301-763-8000 x7552