Africa: Drought and Floods Hazards Assessment

Report
from US Agency for International Development
Published on 06 Feb 2003
The sea surface temperatures in the Indian Ocean remain, generally, above normal. Several weeks ago we indicated that the upper level winds were not supportive of tropical cyclone activity. However, the pattern has undergone a substantial change and we have entered a period when upper level winds in the area are conducive to cyclone formation over the Indian ocean area. We anticipate that we will have increased cyclone activity for several weeks.

The remains of Cyclone Fari dropped up to 230 mm along the west coast of Madagascar on January 29 as the storm exited the island and entered the Mozambique Channel. Up to 65 mm fell on the same day in northern Zimbabwe, but drought persisted from southern Mozambique through southern and western Zimbabwe, northern South Africa, and eastern Botswana, as this region saw negligible rainfall during the past week. Heavy showers continued over Malawi and northern Mozambique nearly each day, and also developed over Angola and Namibia on February 3-4. In North Africa, heavy rains struck north-central and northeastern Algeria and northern Tunisia during the past week, following heavy rains the preceding week. Totals during January 28 to February 3 reached 50-75 mm in several locations, with the bulk of the rain falling on January 31 and February 1.

Click here to see MAP: Africa Weather Hazards Assessment

AFRICA WEATHER HAZARDS ASSESSMENT EXPLANATION FEBRUARY 6-12, 2003

1) From February 2-4, heavy rains with accumulated totals locally greater than 200 mm fell over parts of central and eastern Angola, causing increased soil moisture and river levels. As much of this rainfall was observed to fall over the Zambezi basin in eastern Angola, total basin precipitation for the period was much higher than normal and may lead to local areas of stream flooding. Meteorological forecast models are indicating a chance for rainfall totals to exceed 100 mm within the region and during the next seven days.

2) High pressure continues to inhibit precipitation forming mechanisms throughout much of Zimbabwe, northeastern Botswana, northeastern South Africa, and southern Mozambique, and short term drought exists as a result. Seasonal rainfall totals continue to be much less than normal throughout the region and this pattern is expected to continue during the next few weeks at least, with only local relief likely. As seen from satellite based agricultural and meteorological products, the lack of rainfall in these areas is leading to moisture problems for most crops, and the hazard region is expanding.

3) Heavy rains that fell throughout much of January in parts of northern Mozambique and northern Madagascar have resulted in thoroughly saturated soil conditions, and additional precipitation is expected during the next seven days. Although weekly rainfall totals for the current forecast period will likely remain below 100 mm, localized accumulations exceeding 150 mm are possible. The high pressure area that is leading to drought hazard region #2 is also partially responsible for the excessive rainfall seen in these areas, as converging winds continue to funnel moisture into the region, and daytime heating leads to daily thunderstorms.

4) Long term drought continues to affect parts of central and north central Ethiopia as well as eastern Eritrea, as little to no rainfall has been recorded recently. Meteorological forecast models and infrared satellite products are showing the continued possibility for a few light showers in Ethiopia, though no accumulations are likely. Minor season rainfall normally begins in mid February or early March.

5) Little to no rainfall has been recorded in the drought affected area of southern Mauritania during recent months, and no rainfall is expected in the near future. Poor rainfall during the previous season continue to result in hydrological dryness throughout the region.

6) With no rainfall noted in the past months, reservoir levels throughout much of Guinea remain below normal, and problems continue with hydroelectric power generation. Seasonal rainfall normally begins in late March (south) to early May (north) in the country.

Author: Timothy Love