AFMS ppt PowerPoint Presentati by wuyunyi

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									                 The African Monsoon
                 Recent Evolution and
                    Current Status


                         Update prepared by
                   Climate Prediction Center / NCEP
                              6 July 2010

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

• During the past seven days, heavy rains may have
  resulted in flooding in local areas in southwestern Mali,
  while the west coast of Senegal registered its first
  significant rainfall amount this season.


• Rainfall diminished significantly over Burkina Faso during
  the period.
        Rainfall Patterns: Last 7 Days




During the past seven days, in the Sahel, for the first time this season, the western
areas of Senegal registered significant rainfall amounts, and the east increased its
moisture surpluses. Heavy rains pounded local areas in southwestern Mali, while
lighter rains fell over Burkina Faso and western Niger. Rainfall also diminished over
most areas in the Gulf of Guinea region and in central Africa, except for southern
Cameroon, where totals were above average. Rainfall was also locally moderate to
heavy in southern Sudan, western Ethiopia, southwestern Kenya, and northeastern
Uganda.
     Rainfall Patterns: Last 30 Days




During the past 30 days, rainfall was above average in the southern half of
Senegal, southwestern Mali, and portions of Niger. Rainfall was also above
average along portions of the Gulf of Guinea from Cote d’Ivoire to Nigeria. The
western part of central Africa received above average rainfall . Further to the east,
rainfall was suppressed over southern Sudan and enhanced in western Ethiopia.
     Rainfall Patterns: Last 90 Days




During the past 90 days, southeastern Guinea, Liberia, and coastal areas of Cote
d’Ivoire experienced above average rainfall. However, rainfall was below average
over parts of northern Nigeria. Rainfall was above average over the western end
of central Africa, but moisture deficits prevailed over southern DRC. Rainfall was
locally heavy in portions of the of the Greater Horn of Africa, but suppressed in
central Kenya and much of Tanzania.
     Rainfall Patterns: Last 180 Days




During the past 180 days, rainfall was above average along the western Gulf of
Guinea coastline, much of central and eastern Africa, and parts of southern Africa.
However, Tanzania and western, central and the northern tip of Madagascar had
below average rainfall.
                       Recent Rainfall Evolution




Daily evolution of precipitation during the last 90 days at selected regions indicates a good start
to the rainy season in western Senegal (lower panel – left). Despite the dry spell of the previous
week, cumulative totals remain above average in central Burkina Faso (bottom panel – right).
Moisture surpluses continue to increase in western Ethiopia (upper panel – right).
             Atmospheric Circulation:
                  Last 7 Days




The 850 hPa wind anomaly (left panel) reflected westerly wind anomalies across
the tropical eastern Atlantic converging with low level easterly wind anomalies
over the western part of the Sahel, resulting in enhanced rainfall in this region.
The 200 hPa wind anomaly (right panel) featured an upper level anticyclonic-
cyclonic-anticyclonic triplet extending from the eastern Atlantic to Asia. This
system is associated with a strengthening of a subtropical ridge in the southern
hemisphere and consistent with enhanced rainfall in western Africa.
                     NCEP GEFS Model Forecasts
                      Non-Bias Corrected Probability of
                         precipitation exceedance
                       Week-1: Valid 7 - 13 June, 2010
                      Week-2: Valid 14 – 20 July, 2010




For week-1, there is a high chance for precipitation to exceed 50 mm over parts of
Guinea, Sierra Leone, along the coast of Nigeria and parts of Cameroon. There is also
a high chance for rainfall to exceed 50 mm over western Ethiopia. For week-2, there is
a high chance for precipitation to exceed 50 mm over Guinea and parts of western
Ethiopia.
Experimental Week-1 Precipitation Outlooks
       Week-1 Outlook   7 July – 12 July, 2010


               1. There is an increased chance for above average
               rainfall over western Sahel: Low level westerly wind
               anomalies from the Atlantic associated with an
               anomalous cyclonic circulation are expected to enhance
               rainfall in the region.
               Confidence: Moderate

               2. There is an increased chance for below average
               rainfall along the Gulf of Guinea coast. The
               anomalous low level divergence and the northward shift
               of moisture convergence away from the Gulf of Guinea
               are expected to suppress rainfall in this region.
               Confidence: Moderate

               3. There is an increased chance for above average
               rainfall over western Ethiopia: The stronger than
               normal moist cross equatorial flow from the southern
               hemisphere is expected to enhance rainfall in the region.
               Confidence: Moderate
Experimental Week-2 Precipitation Outlooks
        Week-2 Outlook 13 – 19 July, 2010



                      No forecast – Climatology suggested.
                                   Summary
•   During the past seven days, in the Sahel, for the first time this season, the
    western areas of Senegal registered significant rainfall amounts, and the east
    increased its moisture surpluses. Heavy rains pounded local areas in
    southwestern Mali, while lighter rains fell over Burkina Faso and western Niger.
    Rainfall also diminished over most areas in the Gulf of Guinea region and in
    central Africa, except for southern Cameroon, where totals were above
    average. Rainfall was also locally moderate to heavy in southern Sudan,
    western Ethiopia, southwestern Kenya, and northeastern Uganda.
•   During the past 30 days, rainfall was above average in the southern half of
    Senegal, southwestern Mali, and portions of Niger. Rainfall was also above
    average along portions of the Gulf of Guinea from Cote d’Ivoire to Nigeria. The
    western part of central Africa received above average rainfall . Further to the
    east, rainfall was suppressed over southern Sudan and enhanced in western
    Ethiopia.
•   During the past 90 days, southeastern Guinea, Liberia, and coastal areas of
    Cote d’Ivoire experienced above average rainfall. However, rainfall was below
    average over parts of northern Nigeria. Rainfall was above average over the
    western end of central Africa, but moisture deficits prevailed over southern
    DRC. Rainfall was locally heavy in portions of the of the Greater Horn of Africa,
    but suppressed in central Kenya and much of Tanzania.
•   For week-1, there is an increased chance for above average rainfall over the
    western areas of the Sahel and Ethiopia. There is an increased chance for
    below average rainfall along the Gulf of Guinea coast.

								
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