Download The African Monsoon Recent Evolution and Current Status Update prepared by

The African Monsoon
Recent Evolution and
Current Status
Update prepared by
Climate Prediction Center / NCEP
02 June 2008
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
• Experimental Week-1 Outlook
• Summary
Highlights:
Last 7 Days
• Light or no rain fell in the southern areas
of the Sahel as the rainy season is
generally off to a slow start in this
subregion.
• Beneficial rains fell in eastern parts of the
Gulf of Guinea region.
• Near average rains fell in western Ethiopia
and in the regions adjacent to Lake
Victoria.
Rainfall Patterns: Last 180
Days
Over the past 180 days, rainfall was below average over most areas in the Gulf of
Guinea region, central Africa, and parts of the Greater Horn of Africa. Rainfall was
above average over portions of Tanzania and in parts of southern Africa, except
for northern and eastern Madagascar, and locally the southern areas of Zimbabwe
and Mozambique.
Rainfall Patterns: Last 90 Days
Over the past 90 days, rainfall was below average over most areas in the Gulf of
Guinea region, central Africa, and parts of the Greater Horn of Africa. Rainfall was
above average in local areas in southern Africa.
Rainfall Patterns: Last 30 Days
Over the last 30 days, rainfall was below average over most of Ethiopia, Kenya,
Uganda, northwestern Tanzania, Rwanda, and Burundi. Rainfall was also below
average over portions of central Africa and along portions of the Gulf of Guinea
coast.
Rainfall Patterns: Last 7 Days
During the past 7 days, rainfall was near average across most crop areas in
Africa, except in local areas along the Guinean coast and in central Kenya and
southwester Ethiopia, where rainfall was slightly below average.
Recent Rainfall Evolution
Moisture deficits persisted in portions of the northern Horn of Africa (top panel right); Western Kenya and Uganda continued to register below average rainfall
(bottom panel – right); Below average rains also sustained moisture deficits
over parts of the Gulf of Guinea region (bottom panel – left).
Atmospheric Circulation:
Last 7 Days
Over the past 7 days, the 850 hPa wind anomaly (left panel) featured a westerly
wind anomalies in the eastern Atlantic north of the equator. Easterly wind
anomalies are evident in the central Indian Ocean. The 200 hPa wind anomaly
(right panel) features a northeasterly flow across northern Africa feeding into
strong westerlies in the Indian Ocean south of the equator.
Rainfall Climatology: 27 May2June
Rainfall totals for the week 27 May – 2 June range between 15 and
45 mm over the Gulf of Guinea region, extending north into the
southern areas of the Sahel, western Ethiopia, southwestern Kenya,
eastern Uganda, and along coastal Kenya and northeast Tanzania.
NCEP GEFS Model Forecasts
Non-Bias Corrected Probability of
precipitation exceedance – Week-1
Valid 3 June - 9 June, 2008
NCEP global ensemble forecast system (GEFS) suggests a high tilt in the odds
(90% or above) for precipitation to exceed 25 mm along the Guinean coast, as well
as coastal Kenya and northeastern Tanzania, the western Ethiopian highlands,
and northern central Africa (left panel). Areas with the highest chance for
precipitation to exceed 50 mm (right panel) include western Ethiopia, northeast
DRC, Cameroon, and sections along coastal Gulf of Guinea.
Experimental Week-1 Precipitation Outlook
Valid 27 May - 2 June, 2008
1.
An increased chance for above average
rainfall along the Guinean coastline, from Liberia to
Nigeria: The enhanced phase of the MJO, a low pressure,
System and the low level moisture advection from the Gulf
of Guinea are expected to enhance rainfall in this region.
Confidence: High
2.
An increased chance for above average
rainfall over western Ethiopia: The active phase of the
MJO is expected to enhance precipitation in this area.
Confidence: Moderate
3.
An increased chance for above average
rainfall along the coasts of northern Kenya and
southern Somalia: Low level moisture advection from the
western Indian ocean is expected to enhance precipitation
in this area.
Confidence: Moderate
Summary
•
Over the past 7 days, light to moderate rains fell over parts of the Gulf of
Guinea region, including eastern Cote d’Ivoire, Ghana, Togo, and Benin.
Light or no rain fell in the southern areas of the Sahel, as the rainy season
is off to a slow start in this region. Rainfall was below average over
portions of Burkina Faso. In central Africa, rainfall was lighter than average
over CAR, northern Congo, and in local areas in northern DRC. In the
Greater Horn of Africa, rainfall was below average in southwestern Ethiopia
and central Kenya, while eastern Uganda and the area in the vicinity of
Lake Victoria received above average rainfall. Generally, seasonably dry
weather prevailed in southern Africa.
•
Cumulative rainfall over many areas in the Gulf of Guinea region over the
past 30 and 90 days remain below average. The areas most severely
affected include western Cote d’Ivoire, which registered only 50% of the
cumulative 90-day rainfall totals. As the rainy season begins to wind down
in many parts of the Greater Horn of Africa, Parts of the region are likely to
end the season with significant moisture deficits. Parts of Kenya, Uganda,
and Ethiopia registered only a little bit more than 50% of the cumulative 90day total rainfall.
•
For the period 3 June – 9 June 2008, there is an increased chance for above
average rainfall along the Guinean coastline, northern central Africa,
southwestern Ethiopia, and along the coastal boundary between Kenya and
Somalia.