The sea surface temperatures in the Indian Ocean remain, generally, above normal. By itself, this would suggest a continued positive impact on the development of tropical cyclones. However, it now appears that we have entered a period when upper level winds in the area will not be conducive to cyclone formation over the Indian ocean area. We anticipate that the latter effect will dominate and that we will have reduced cyclone activity for several weeks. The exception appears to be in a thin band at about 80E where both the warm water and the upper air winds are supportive of possible cyclone development.
With respect to the weather over Africa, the major focus is on the dry conditions over much of the southern portions of the continent. In southern Mozambique monthly totals are around 150 mm below normal, while similar conditions exists in Zimbabwe and southern Zambia. Other critical areas like the maize triangle in South Africa and eastern Botswana received 20 to 40 mm of rain and locally heavier amounts around January 16-18. This should help relieve some short-term dryness in the region. Elsewhere, heavy amounts of rain fell in northern Mozambique and the north and central portions of Madagascar. Daily rain amounts over these areas ranged from 30 to 70 mm. Several reports have been received regarding mudslides in northern Madagascar and flooding in river basins in north and central Mozambique. In northern Tunisia and Algeria heavy rains and flooding was reported on January 16 and 17. Local amounts were over 70 mm.
WEEKLY AFRICAN WEATHER HAZARDS ASSESSMENT STATEMENT
JANUARY 23, 2003 DISCUSSION:
1) Recent rains in northern Tunisia and extreme areas in northern Algeria has resulted in saturated conditions and some local flooding. Expect more rain throughout the period which could induce local flooding in some prone areas.
2) Hydrological dryness continues across much of southern Mauritania resulting in poor pasture conditions. Significant rains are not expected until the next growing season, which generally begins in July.
3) Dryness throughout recent years has resulted in poor pasture conditions and low water supplies across central Ethiopia, and adjacent portions of Eritrea and Djibouti. Rainfall is not forecast over the region within the next week.
4) Below normal rainfall totals in Guinea has resulted in low reservoir levels, which aid in the generation of hydro-electric power. Improvement is expected around April or the start of the next rainy season in the region.
5) Southern Africa has remained dry over the past week, and little rain is forecast in the coming period. Several reports say that much of the region is 100-200 mm below normal, with some local areas over 200 mm below normal. The area highlighted should continue to be monitored closely for the potential for crop failure due to extremely dry conditions. The region of greatest concern is southern Mozambique and most of Zimbabwe.
6) Saturated conditions, which continue in southern Malawi, north and central Mozambique, and the northern two-thirds of Madagascar could lead to isolated areas of flooding as rains continue over the next week. Flood prone areas should be monitored closely as convective showers could bring local amounts of 100-200 mm of rain over the hazard period.
Author: Kevin B Laws