The African Monsoon Recent Evolution and Current Status

1. The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 28 April 2008 For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/African_Monsoons/precip_monitoring.shtml

2. Outline • Highlights • Recent Evolution and Current Conditions • NCEP GEFS Forecasts • Experimental Week-1 Outlook • Summary

3. Highlights:Last 7 Days • Heavy rains soaked southern Kenya and northern Tanzania. Uganda received sizable rainfall amounts. Central Ethiopia continued to register light or no rain. • Southern Burkina Faso registered early rains, while light or no rain resulted in moisture deficits in western Cote d’Ivoire and eastern Liberia. • Sizable rainfall amounts resulted in above average rainfall in southern Zimbabwe.

4. Rainfall Patterns: Last 7 Days During the past 7 days, rainfall was above average in local areas in southern and northern Kenya along the border with Ethiopia. Rainfall was also above average over parts of CAR, Cameroon, and southern Burkina Faso. In contrast, rainfall was below average in local areas in the Gulf of Guinea region, central Ethiopia, and in much of Gabon, Congo, and southern DRC.

5. Rainfall Patterns: Last 30 Days Over the last 30 days, rainfall was above average along coastal Tanzania, southern Somalia, and portions of western Ethiopia. Rainfall was below average over the central areas of Ethiopia and Kenya, along the Gulf of Guinea coast, as well as parts of southern Africa.

6. Rainfall Patterns: Last 90 Days Over the past 90 days, rainfall was above average over parts of northern Namibia, southeastern Angola, along the northern coast of Mozambique, and most areas in central Tanzania. Rainfall was below average over most areas in northern Kenya, central Ethiopia, as well as in areas along the Guinean coast.

7. Rainfall Patterns: Last 180 Days Over the past 180 days, rainfall was above average across most areas in southern Africa, including in Tanzania. Rainfall was below average over portions of the central areas of Africa and the Greater Horn, including Kenya, Uganda, and Ethiopia. Rainfall was also below average over the Gulf of Guinea region.

8. Recent Rainfall Evolution After a brief pause, the Belg rains returned to near average level in southern Ethiopia (top panel - right); Rainfall has been healthy in southwestern Kenya and northern Tanzania (bottom panel – right); Below average rains continued to sustain moisture deficits over parts of the Gulf of Guinea region (bottom panel – left).

9. Atmospheric Circulation:Last 7 Days Over the past 7 days, the 850 hPa wind anomaly (left panel) featured easterly wind anomalies over the central Indian Ocean (IO). Upper level easterly wind anomalies stretching from Asia westward into Africa (right panel) were evident.

10. Rainfall Climatology: 29 Apr – 5 May Rainfall totals for the week 29 Apr – 5 May range between 15 and 45 mm over the Gulf of Guinea region, parts of CAR, and Ethiopia. Rainfall range between 45 and 75 mm parts of the GHA and CAR.

11. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance – Week-1Valid 29 Apr - 5 May, 2008 NCEP global ensemble forecast system (GEFS) suggests a high tilt in the odds (90% or above) for precipitation to exceed 25 mm along coastal Kenya and northern Tanzania, the western Ethiopian highlands, central Africa, and along the Gulf of Guinea region (left panel). Areas with highest chance for precipitation to exceed 50 mm (right panel) include coastal central Africa and sections of western Ethiopia.

12. Experimental Week-1 Precipitation OutlookValid 29 Apr - 5 May, 2008

13. Summary • Over the past 7 days, scattered moderate to heavy showers resulted in above average rainfall in local areas in southern and northern Kenya along the border with Ethiopia. Rainfall was also above average over parts of CAR, Cameroon. Early rains fell over southern Burkina Faso. In contrast, rainfall was below average in local areas in the Gulf of Guinea region, and in parts of CAR, including Gabon, Congo, and southern DRC. • Following a late start to the rainy season, portions of the GHA have registered above average rainfall over the past 30 days. These include the breadbasket of southwestern Kenya and northern Tanzania. However, light to moderate rains resulted in moisture deficits over central Ethiopia, and over many areas along the Gulf of Guinea region. Rainfall was also below average over the western part of central Africa, including western DRC, Congo, and Gabon. • Over the past 90 days, rainfall was above average over parts of southern Africa, including northern Namibia, southeastern Angola, along the northern coast of Mozambique, and most areas in central Tanzania. However, an early retreat of the rains resulted in below average rainfall in much of Zambia, Zimbabwe, and central and southern Mozambique. Rainfall was below average over most areas in northern Kenya, central Ethiopia, as well as in areas along the Guinean coast. • For the period 22– 28 April 2008, the NCEP global ensemble forecast system (GEFS) suggests a high tilt in the odds (90% or above) for precipitation to exceed 25 mm along coastal Kenya and northern Tanzania, the western Ethiopian highlands, central Africa, and along the Gulf of Guinea region (left panel). Areas with highest chance for precipitation to exceed 50 mm (right panel) include coastal central Africa and sections of western Ethiopia.