The African Monsoon Recent Evolution and Current Status
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The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 29 February 2008
Outline • Recent Evolution and Current Conditions • NCEP GEFS Forecasts • Summary
Rainfall Patterns: Last 90 Days Over the past 90 days, rainfall was above average in many areas over southern Africa. The largest rainfall departures occurred over southern Angola and northern Mozambique. Recent rains in Madagascar helped erase the moisture deficits observed earlier in the southern part of the country. However, rainfall was below average along the east coast. A recent dry spell contributed to below average rainfall over southern Zimbabwe.
Rainfall Patterns: Last 30 Days Over the last 30 days, the recent dry spell in the areas including Zimbabwe, southern Botswana, northeastern South Africa, and southern Mozambique resulted in moisture deficits in this subregion. In contrast, moderate to heavy rains resulted in moisture surpluses over central Namibia, southeastern Angola, and the southern half of Tanzania. Tropical Cyclone Ivan made landfall in Madagascar and contributed to above average rainfall in this region including northern Mozambique.
Rainfall Patterns: Last 7 Days During the past 7 days, light rains resulted in below average rainfall across most areas in southern Africa. The exceptions were local areas in southern and northwestern Madagascar, sectors along the northern coast of Mozambique, central Namibia, and portions of the Eastern Cape Province of South Africa. Near average rains fell over northeastern South Africa.
Recent Evolution: Rainfall Recently, light rains resulted in below average rainfall over central Mozambique, Zimbabwe, and eastern Botswana (top panel). Below average rainfall returned to eastern Madagascar (middle panel) after the period of wetness associated with Tropical cyclone Ivan. Over the last 30 days, rainfall has been below average across eastern South Africa. However, wet conditions returned to this region during the past week.
NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance – Week-1 Valid Mar 1 -7, 2008 According to the NCEP global ensemble forecast system (GEFS), there is more than 90% chance for precipitation to exceed 75 mm over southern Angola. Elsewhere in southern Africa near or below average rainfall is expected during the period.
Summary • Season-to-date rainfall has been near or above average over many areas in continental southern Africa. However, recent dry spells resulted in drier than average conditions over the last 30 days. • Following extreme heavy rainfall associated with Tropical Cyclone Ivan, drier than average conditions returned to eastern Madagascar, while the west continued to receive above average rainfall. Moderate rains resulted in above average rainfall over central Namibia. • According to the NCEP global ensemble forecasts (GEFS), for the period 1 -7 March 2008, there is a high tilt in the odds to favor near or below average rainfall over most areas in continental southern Africa, except for southern Angola where there is 90% chance for rainfall to exceed 75 mm. .