African Monsoon: Recent Evolution & Current Status Update

1. The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 22 February 2008

2. Outline • Recent Evolution and Current Conditions • NCEP GEFS Forecasts • Summary

3. Rainfall Patterns: Last 90 Days Over the past 90 days, persistent extremely heavy rainfall resulted in moisture surpluses over the southern half of Angola. Rainfall was also above average across much of the remainder of southern Africa, including portions of western Zambia, northern and central Mozambique, northern Zimbabwe, and Botswana. However, light than average rains fell over portions of northeastern South Africa, the southern areas of Mozambique and Zimbabwe, and locally along the east coast of Madagascar.

4. Rainfall Patterns: Last 30 Days Moderate to heavy rains persisted over the area encompassing southeastern Angola, southwestern Zambia, and northern Botswana. Most areas in Tanzania, local areas in northern and central Mozambique, and northern and southern Madagascar received above average rainfall. The recent dry spell in the areas including Zimbabwe, southern Botswana, northeastern South Africa, and southern Mozambique resulted moisture deficits in this subregion.

5. Rainfall Patterns: Last 5 Days During the past 5 days, Tropical Cyclone Ivan made land falling in Madagascar and soaked much of the country as well as portions of northern Mozambique. Lighter rains fell over central Mozambique, northern Zimbabwe, and southern Zambia. Dry conditions sustained moisture deficits over the crop growing areas of northeastern South Africa, southern Mozambique, and the southern areas of Zimbabwe.

6. Recent Evolution: Rainfall Recently, light rains in the area including southeastern Angola and western Zambia (top panel) eased flooding over many river basins, including the Zambezi. Rainfall returned over central Mozambique and local flooding may occur. Tropical Cyclone Ivan brought extremely heavy rainfall to Madagascar and enough to offset the accumulated deficits of the past month.

7. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance – Week-1Valid Feb 23-29, 2008 According to the NCEP global ensemble forecast system (GEFS), the likelihood for precipitation to exceed 75 mm is extremely low over most areas in southern Africa. As a result, most areas in continental southern Africa and Madagascar are expected to receive below average rainfall during the period. There is however 95% chance for precipitation to exceed 75 mm along the west coast of Madagascar and over portions of southern Angola.

8. Summary • Tropical Cyclone Ivan made land falling in Madagascar and resulted in extremely heavy rainfall and flooding in many areas. The moisture surpluses helped offset the deficits accumulated in the south since the beginning of the rainy season. Northern Mozambique also received above average rainfall as a result of Ivan. • The rainy season has so far been beneficial to crop production in many areas in southern Africa. However, northeastern South Africa, Zimbabwe, and Botswana have recently failed to register significant rainfall amounts. • Rainfall recently abated in southeastern Angola and western Zambia. However, season-to-date rainfall remains above average. • According to the NCEP global ensemble forecasts (GEFS), there is an increased chance for most areas in continental southern Africa to register below average rainfall during the period 23-29 February, 2008.