The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2

The African Monsoon
Recent Evolution and
Current Status
Include Week-1 and Week-2
Outlooks
Update prepared by
Climate Prediction Center / NCEP
06 May 2013
For more information, visit:
http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/African_Monsoons/precip_monitoring.shtml
Outline
• Highlights
• Recent Evolution and Current Conditions
• NCEP GEFS Forecasts
• Summary
Highlights:
Last 7 Days
•
Moderate to locally heavy rainfall resulted in moisture surpluses
across portions of central African region and South Sudan.
•
Suppressed rainfall prevailed over eastern Nigeria, Kenya and
southern Somalia.
•
Week-1 outlooks call for an increased chance for above-average
rainfall over eastern Burkina Faso, southwestern Niger, northern
Benin, northern Nigeria, northeastern DRC, southern South Sudan,
Uganda, western Kenya, Rwanda, coastal Kenya and parts of
Tanzania.
Rainfall Patterns: Last 7 Days
During the past seven days, rainfall was above-average over parts of Ghana, Togo, Benin, local
areas in Gabon, northern Congo, CAR, northern DRC, South Sudan, parts of Ethiopia, and local
areas in Somalia, Kenya and Madagascar. In contrast, local areas in Guinea, eastern Nigeria,
western Cameroon, local areas in Congo and DRC, parts of northern Angola, many parts of
Kenya, southern Ethiopia and southern Somalia.
Rainfall Patterns: Last 30 Days
During the past 30 days, below-average rainfall was observed over eastern Guinea, Liberia,
southern Cote D’Ivoire, southern Ghana, many parts of Nigeria and Cameroon, northern Gabon,
local areas in South Sudan, western Ethiopia, southern Angola, local areas in Kenya and
Tanzania, and much of Madagascar. In contrast, eastern Burkina Faso, Togo, Benin, local areas
in southern Nigeria, Cameroon, Congo and Gabon, many parts of CAR and DRC, northern
Angola, local areas in South Sudan, Uganda, western Kenya, eastern and southern Ethiopia,
parts of Tanzania, and local areas in Mozambique and South Africa had above-average rainfall.
Rainfall Patterns: Last 90 Days
During the past 90 days, parts of Togo and Benin, local areas in Cameroon, Equatorial
Guinea, western Gabon, parts of CAR, parts of Angola, northern DRC, southern and
astern Ethiopia, western Kenya, southern Somalia, local areas in Mozambique, northern
Angola, and southern Madagascar received above-average rainfall. In contrast, rainfall
was below-average over local areas in Gabon, southern and eastern Angola, local areas
in DRC, much of Zambia and Namibia, Botswana, southern Tanzania, northern
Mozambique and northern Madagascar.
Rainfall Patterns: Last 180 Days
During the past 180 days, rainfall was above-average over local areas in the Gulf of Guinea region,
portions of CAR, western Gabon, northern DRC, local areas in Angola, much of Uganda and
Kenya, southern Ethiopia, southern Somalia, parts of Mozambique, northeastern South Africa,
and southern Madagascar. Eastern Gabon, portions of DRC, southern Tanzania, southern and
eastern Angola, much of Namibia, parts of Botswana, local areas in South Africa, and northern
Madagascar had below-average rainfall.
Recent Rainfall Evolution
Daily evolution of rainfall over the last 90 days at selected places reflects early season moisture deficits
over Nigeria (bottom panel-left). Moderate to heavy rainfall sustained rainfall surpluses over southern
Ethiopia (top panel-right). Seasonal total rainfall remained above-average despite the recent decreasing
tendency over Kenya (bottom panel right).
Atmospheric Circulation:
Last 7 Days
The 850hPa wind anomaly (left panel) featured broad cyclonic circulation over
Northwest Africa. Anomalous broad upper-level cyclonic circulation is also evident over
northern Africa (right panel). Anomalous lower-level easterly flow was observed across
central and western parts of equatorial Africa region.
NCEP GEFS Model Forecasts
Non-Bias Corrected Probability of
precipitation exceedance
Week-1: Valid May 7 – May 13, 2013
Week-2: Valid May 14 – May 20, 2013
For week-1 (left panel) and week-2 (right panel), there is an increased chance for
rainfall to exceed 50 mm over equatorial Africa and the Greater Horn of Africa regions,
with a decreasing tendency across the Greater Horn of Africa during week-2.
Experimental Week-1 Precipitation Outlooks
May 7 – May 13, 2013
1. There is an increased chance for above-average
rainfall over eastern Burkina Faso,
southwestern Niger, northern Benin and
northern Nigeria: Anomalous lower-level wind
convergence is expected to enhance rainfall in the
region. Confidence: Moderate
2. There is an increased chance for above-average
rainfall over northeastern DRC, southern South
Sudan, Uganda, western Kenya, Rwanda, and
northern Tanzania: The projected phase of the
MJO is expected to enhance rainfall in the region.
Confidence: Moderate
3. There is an increased chance for above-average
rainfall along coastal Kenya and northeastern
Tanzania: Stronger than normal cross-equatorial
flow and its associated convergence is expected to
enhance rainfall in the region. Confidence: Moderate
Experimental Week-2 Precipitation Outlooks
May 14 – May 20, 2013
1. There is an increased chance for above-average
rainfall over southern Mali: Anomalous lower-level
cyclonic circulation is expected to enhance rainfall in
the region. Confidence: Moderate
2. There is an increased chance for below-average
rainfall over southeastern Ethiopia and Somalia:
Combination of the projected phase of the MJO and
anomalous upper-level cyclonic circulation is
expected to suppress rainfall in the region.
Confidence: Moderate
Summary
•
During the past seven days, rainfall was above-average over parts of Ghana, Togo, Benin, local
areas in Gabon, northern Congo, CAR, northern DRC, South Sudan, parts of Ethiopia, and local
areas in Somalia, Kenya and Madagascar. In contrast, local areas in Guinea, eastern Nigeria,
western Cameroon, local areas in Congo and DRC, parts of northern Angola, many parts of
Kenya, southern Ethiopia and southern Somalia.
•
During the past 30 days, below-average rainfall was observed over eastern Guinea, Liberia,
southern Cote D’Ivoire, southern Ghana, many parts of Nigeria and Cameroon, northern Gabon,
local areas in South Sudan, western Ethiopia, southern Angola, local areas in Kenya and
Tanzania, and much of Madagascar. In contrast, eastern Burkina Faso, Togo, Benin, local areas
in southern Nigeria, Cameroon, Congo and Gabon, many parts of CAR and DRC, northern
Angola, local areas in South Sudan, Uganda, western Kenya, eastern and southern Ethiopia,
parts of Tanzania, and local areas in Mozambique and South Africa had above-average rainfall.
•
During the past 90 days, parts of Togo and Benin, local areas in Cameroon, Equatorial Guinea,
western Gabon, parts of CAR, parts of Angola, northern DRC, southern and astern Ethiopia,
western Kenya, southern Somalia, local areas in Mozambique, northern Angola, and southern
Madagascar received above-average rainfall. In contrast, rainfall was below-average over local
areas in Gabon, southern and eastern Angola, local areas in DRC, much of Zambia and
Namibia, Botswana, southern Tanzania, northern Mozambique and northern Madagascar.
Week-1 outlooks call for an increased chance for above-average rainfall over eastern Burkina
Faso, southwestern Niger, northern Benin, northern Nigeria, northeastern DRC, southern South
Sudan, Uganda, western Kenya, Rwanda, coastal Kenya and parts of Tanzania.
•