African Centre of Meteorological Application for Development
Centre Africain pour les Applications de la Météorologie au
Développement
Ten Day Climate Watch Bulletin
N° 30
Dekad 1st to 10th November, 2013
HIGHLIGHTS
Well above normal precipitation was observed over southern Cameroon and CAR,
eastern Gabon, Most of Congo and DRC, border between South Sudan and Uganda,
parts of Zimbabwe, South Africa and Madagascar. However, well below normal
precipitation was observed over bordering area of Uganda-Kenya-Burundi-RwandaTanzania, Equatorial Guinea, western Gabon and extreme east of DRC.
During the period 6th to 13th November, 2013, high probability of moderate precipitation
exceeding 75mm is expected over western Cameroon, greater parts of Gabon and Congo,
north-east of DRC, central Angola, Uganda and Kenya. From 14th to 20th November, there
will be persistence of moderate precipitation exceeding 75 mm over parts of Gabon, DRC and
central Angola.
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1.0 GENERAL METEOROLOGICAL SITUATION
Subsection 1.1 provides the strengths of the surface pressure systems and ITD, CAB and ITCZ displacements
while subsection 1.2 is on Troposphere and gives a brief on monsoon, thermal index (TI) regimes and relative
humidity.
1.1 SURFACE
1.1.1 Pressure Systems
 The Azores High of 1026hPa strengthened by 2hPa compared to the previous dekad and by 5hPa in
relation to the climatological mean (1971-2000). It was located at 36ºN/27ºW over North Atlantic
Ocean.

St. Helena High of 1025hPa weakened by 1hPa compared to the previous dekad and strengthened by
7hPa in relation to the climatological mean (1971-2000). It was located at 35°S/25°W over South
Atlantic Ocean.

Mascarene High of 1023hPa strengthened by 1hPa compared to the previous dekad and remained
stable in relation to climatological mean (1971-2000). It was located at 30°S/94°E over South Indian
Ocean.

The Thermal Low of 1008hPa was located at 11°N/18°E over southern Chad. It remained stable
compared to the previous dekad.
Fig. 1a: Pressure Anomaly at MSL 1 to 10 Nov 2013
(source NOAA/NCEP)
Fig. 1b: Pressure Anomaly at MSL 1 to 10 Nov 2013 (source
NOAA/NCEP)
1.1.2 Inter-Tropical Discontinuity (ITD), Inter-Tropical Convergence Zone (ITCZ)
and Congo Air Boundary (CAB)
Between the 3rd dekad of October (blue line) and 1st dekad of November (black line), 2013, the ITD moved
southward by 1 to 4 degrees from north Atlantic to southern Sudan. The CAB remained quasi stationary
over Uganda, Tanzania, DRC and Zambia. The ITCZ moved southward by more than 7 degrees over
Kenya, Somalia and Indian Ocean (Figure 2).
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Fig. 2: The mean position of ITD, CAB and ITCZ 1st dekad of Nov (black), 3rd dekad of October 2013 (blue)
The red and green triangles represent their maximum and minimum displacements respectively.
1.2 TROPOSPHERE
1.2.1 African Monsoon
At 925hPa level (figure 3a), weak to moderate intensity of the monsoon winds were observed over most parts of
the Gulf of Guinea (GoG) countries. The intensity of the monsoon at 850hPa which prevailed over the GoG and
most of central Africa countries was moderate. (figure 3b).
Fig. 3a: Mean wind at 925 hPa in m/s 1 to 10 Nov
2013 (Source: NOAA/NCEP)
Fig. 3b: Mean wind at 850 hPa in m/s 1 to 10 Nov 2013,
(Source: NOAA/NCEP)
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1.2.4 Thermal Index (TI) Regime
During the first dekad of November, the Thermal Index (TI) regime at 300hPa in (figure 5a) had isotherm value
of 242°K over southern Nigeria, Chad and Sudan, northern Cameroon and central Ethiopia and Somalia. It
extended over northern Angola, central Zambia and Malawi and southern Tanzania. The high TI regime ≥242°K
provided prospects for heavy rainfall.
The analysis in figure 5b shows increased temperature anomalies of 0.5 to 2.5°K compared to normal (19712000) over the entire continent except over bordering area South Africa where negative anomalies of 0.5 to 1°K
were recorded.
Fig. 5a: TI at 300hPa (°k) 1 to 10 Nov 2013
(Source: NOAA/NCEP)
Fig. 5b: TI Anomaly at 300hPa (°k) 1 to 10 Nov 2013
(Source: NOAA/NCEP)
1.2.5 Relative Humidity (RH) at 850 hPa
The 850hPa level (figure 6a) had high RH value (≥60%) during the first dekad of November over GoG
countries, Central and Eastern Africa countries, northern Angola and Zambia and Madagascar with peaks of
80% over Great lakes countries and central Ethiopia. The remaining northern and southern parts of the continent
observed RH value ≤ 40%.
The RH anomalies for the first dekad compared to the reference period 2002-2011 (figure 6b), were positive
over most of the continent except over Morocco, Tunisia, southern Niger, Nigeria, Northern Cameroon and
southern Chad including most of southern Africa countries.
Fig. 6a: RH (%) at 850hPa 1 to 10 Nov 2013
Fig. 6b: RH Anomaly at 850hPa 1 to 10 Nov 2013
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(Source: NOAA/NCEP/ESRL: PSD)
(Source: NOAA/NCEP/ESRL: PSD)
1.2.6 Relative Humidity (RH) at 700hPa
The 1st dekad of November had high RH value ≥ 70% at 700hPa (figure 7a) over southern of GoG countries,
Central and Eastern Africa countries, Angola, Zambia, Malawi, northwest Mozambique and Zimbabwe.
The parts with threshold RH value ≥ 70% were very favorable for deep convection that generated heavy rainfall
as shown in figure 8.
The 1st dekad of November RH anomalies (figure 7b) were greater than the reference period (2002-2011) over
some parts of continent including most of Algeria, Mauritania, Libya, Mali, Niger, greater part of Central Africa
and East. Over the remaining part of Africa deficit values of RH were observed.
Fig. 7a: RH (%) at 700hPa 1 to 10 Nov 2013
(Source: NOAA/NCEP/ESRL: PSD)
Fig. 7b: RH Anomaly at 700hPa 1 to 10 Nov 2013,
(Source: NOAA/NCEP/ESRL: PSD)
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2.0 PRECIPITATION
Figures 8 indicate observed precipitation estimates in percentage of normal for the 1st dekad of November.
2.1 Precipitation
Well above normal precipitation was observed over coastal Atlantic of GoG countries, Most of Ethiopia,
Somalia, some parts of South Sudan, eastern CAR, border between Congo and DRC and bordering area of
Zambia-Zimbabwe-Namibia. The heavy precipitation resulted from deep convection associated with high TI
regime and RH ≥ 70%. However, below to well below normal precipitation was observed over central
Cameroon, some parts of DRC and northern Zambia.
Details:
 North Africa: Observed generally normal precipitation.
 The Sahel: Observed normal precipitation.
 Gulf of Guinea countries: Observed normal to well above normal precipitation.
 Central Africa countries: observed well above normal precipitation over western Gabon, border
between Congo and DRC.
 GHA countries: observed well above normal precipitation over major part of the region.
 Southern Africa countries: Observed normal to well above normal precipitation.
Figure 8: Cumulative Precipitation in relation to the Reference in % 1 to 10 Nov 2013
(Source: NOAA/NCEP)
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3. Outlook valid for 15th to 28th November 2013
3.1 Precipitation
During the period 15th to 22nd November, 2013, high probability of moderate precipitation exceeding 75mm is
very likely over extreme western Cameroon, greater parts of Gabon, some parts of Congo, central DRC and
Angola, and some small parts of Uganda, Kenya and Ethiopia. From 23rd to 28th November, there will be
persistence of moderate precipitation exceeding 75 mm over parts of Gabon, DRC, central Angola and Uganda.
Otherwise, moderate precipitation is expected over Zambia and Madagascar.
 North Africa: Minimal precipitation amounts will be observed over this sub-region.

The Sahel: Minimal precipitation amounts will be observed over this sub-region.

Gulf of Guinea countries: Precipitation amounts ranging from 20mm to 75mm will be expected
over southern part of the region.
 Central Africa countries: Precipitation amounts ranging from 20mm to 150 mm will be expected
over greater part of the sub-region.
 GHA countries: Likely to observe precipitation amounts ranging between 20mm and 150mm.
 Southern Africa countries: precipitation amounts ranging between 20 and 100mm are likely to
prevail over south-eastern part of this region.
Fig. 9a : Forecast of total precipitation(mm)
forecast 15 to 22 November 2013
(Source : NCEP/GFS)
Fig.9b : Probability forecast of total precipitation
exceeding 75mm, forecast 15 to 22 November
2013 (Source: NCEP/GFS)
Fig.9b : Probability forecast of total
precipitation exceeding 75mm, forecast 23 to 28
November 2013 (Source: NCEP/GFS)
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3.2 Temperature
Neutral to positive anomalies (Figure 10b) will be observed over most parts of the Sahel, eastern Ethiopia,
Kenya, Somalia, Tanzania, Zambia, Zimbabwe, northern Botswana, Namibia, Mozambique and Madagascar.
Neutral to negative anomalies will be recorded over remaining parts of the continent.
Fig. 10b: Temperature Anomaly forecast 15 to 22 November 2013, (Source: COLA)
3.3 Soil Moisture
Fig 11b shows deficit in soil moisture over most parts of the continent except major part of Central Africa and
some parts of Southern Africa countries where increase in soil moisture will be expected.
Fig. 11b: Soil moisture change 15 to 22 November 2013
(Source: COLA)
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