The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 13 April 2009 For more information, visit:

Outline Highlights Recent Evolution and Current Conditions NCEP GEFS Forecasts Summary

Highlights: Last 7 Days Tropical Cyclone Jade made land fall in northeastern Madagascar (5 April) and damped heavy rainfall in the region. Light rains sustained moisture deficits over the breadbasket of southwestern Kenya.

Rainfall Patterns: Last 180 Days Over the past 180 days, rainfall was above average across most areas in continental southern Africa and along the east coast of Madagascar. Rainfall was below average along the northwest coast of Madagascar, northern Angola, southern and central DRC. Rainfall was also below average over southern Kenya. In central Africa, rainfall was below average over Gabon, while northern Congo, and coast Cameroon received above average rainfall. The Gulf of Guinea region in West Africa also received above average rainfall.

Rainfall Patterns: Last 90 Days During the past 90 days, rainfall was above average over northern Namibia and southern Angola. In contrast, rainfall was below average over eastern Zimbabwe, central and southern Mozambique, and western Madagascar. Further to the north, rainfall was above average over western Tanzania, southern Uganda, and eastern DRC. Rainfall was above average on local areas over CAR. Northern Congo, and coastal Cameroon.

Rainfall Patterns: Last 30 Days During the last 30 days, Tropical Cyclones Izilda and Jade damped heavy downpours in parts of Madagascar resulting in above average rainfall in much of this country. Rainfall was also above average over western Tanzania, eastern Zambia, Malawi, and in local areas over northern Mozambique. In contrast, rainfall was below average over much of Angola and parts of DRC. In East Africa, rainfall was below average over southern Kenya and northern Uganda. Rainfall was above average locally over southwestern Ethiopia. In Central Africa, lighter than average rains sustained moisture deficits over Gabon and in local areas over southern Congo. Rainfall was above average in parts of the Gulf of Guinea region of West Africa.

Rainfall Patterns: Last 7 Days During the past week, Tropical Cyclone Jade brought excessive rains over northeastern Madagascar. Areas along the coast received over 100 mm above the mean. However, rainfall was below average in local areas over southern Tanzania, northeastern Zambia, and southern DRC. In East Africa, rainfall was below average over southwestern Kenya, while local areas in northeastern Kenya and southwestern Ethiopia received above average rainfall. Rainfall was also above average over parts of central Africa, including portions of CAR and northern Cameroon. Light rains however resulted below average rainfall over Gabon.

Recent Rainfall Evolution Daily rainfall evolution during the last 90 days shows that rainfall has been steady in the Gulf of Guinea region in West Africa (bottom left). Two tropical cyclones Izilda and Jade that hit Madagascar over the last 30 days helped this region recover from the deficits registered over the past 90 days (bottom right). A recent dry spell sustained moisture deficits over parts of Ethiopia (top right).

Atmospheric Circulation: Last 7 Days Over the past 7 days, the 850 hPa wind anomaly (left panel) featured an anomalous low level cyclonic circulation centered over Madagascar and associated with Tropical Cyclone Jade. The 200 hPa wind anomaly (right panel) featured anomalous upper level divergence over southwest Indian Ocean also associated with Jade.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid April, 2009 Week-2: Valid April, 2009 For week-1, the global ensemble forecast system (GEFS) suggests over 90% chance for precipitation to exceed 50 mm over parts of Central Africa, including southern Congo, Gabon, and southern Cameroon. For week-2, the model exhibits a chance for precipitation to exceed 50 mm over Gabon and central Cameroon.

Experimental Week-1 & Week-2 Precipitation Outlooks Week-1 Outlook Valid April, An increased chance for below average rainfall over parts of central and eastern Africa: As the MJO is projected to propagate east and the active phase located over the Indian Ocean and the Maritime Continent, precipitation is expected to be suppressed over parts of central and eastern Africa. Confidence: Moderate Week-2 Outlook Valid April 2009 Climatology is expected across Africa

Summary During the past week, Tropical Cyclone Jade brought excessive rains over northeastern Madagascar. Areas along the coast received over 100 mm above the mean. However, rainfall was below average in local areas over southern Tanzania, northeastern Zambia, and southern DRC. In East Africa, rainfall was below average over southwestern Kenya, while local areas in northeastern Kenya and southwestern Ethiopia received above average rainfall. Rainfall was also above average over parts of central Africa, including portions of CAR and northern Cameroon. Light rains however resulted below average rainfall over Gabon. During the last 30 days, Tropical Cyclones Izilda and Jade damped heavy downpours in parts of Madagascar resulting in above average rainfall in much of this country. Rainfall was also above average over western Tanzania, eastern Zambia, Malawi, and in local areas over northern Mozambique. In contrast, rainfall was below average over much of Angola and parts of DRC. In East Africa, rainfall was below average over southern Kenya and northern Uganda. Rainfall was above average locally over southwestern Ethiopia. In Central Africa, lighter than average rains sustained moisture deficits over Gabon and in local areas over southern Congo. Rainfall was above average in parts of the Gulf of Guinea region of West Africa. As the MJO is projected to propagate east and the active phase located over the Indian Ocean and the Maritime Continent, precipitation is expected to be suppressed over parts of central and eastern Africa.