African Centre of Meteorological Applications for Development Centre Africain pour les Applications de la Météorologie au Développement

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African Centre of Meteorological Applications for Development Centre Africain pour les Applications de la Météorologie au Développement Ten Days Climate Diagnostics Bulletin N 03 Dekad 3, 21 st to 31

1 African Centre of Meteorological Applications for Development Centre Africain pour les Applications de la Météorologie au Développement Ten Days Climate Diagnostics Bulletin N 03 Dekad 3, 21 st to 31 st January 2018 HIGHLIGHTS Above to well above average precipitation was observed over northern Morocco and Algeria, Gabon, eastern DRC, southern Uganda and Tanzania, much of Zambia, Zimbabwe, Namibia and Botswana, southern Mozambique and northern South Africa. Below to well below average precipitation was observed over northern Tunisia, parts of Congo, western DRC, much of Angola and Madagascar, southern South Africa and northern Mozambique. During the period from 7 th to 13 th February 2018, low to moderate precipitation is likely over northern Morocco, Algeria and Egypt, southern Congo and DRC, northern Angola and much of South Africa. Moderate to heavy precipitation is likely over southern Tanzania, parts of Mozambique and southern Madagascar. Heavy precipitation is likely over northern Zambia, Malawi, Mozambique and Madagascar. During the period from 14 th to 20 th February 2018, low to moderate precipitation is very likely over northern Morocco, southern Gulf of Guinea countries and CAR, parts of South Sudan, southern Angola, Zambia and Zimbabwe, and eastern South Africa. Moderate to heavy precipitation is likely over eastern DRC, southern Tanzania, northern Zambia and Mozambique. Heavy precipitation is likely over western DRC, northern Angola and Madagascar. 1

1.0 GENERAL CLIMATOLOGICAL SITUATION Subsection 1.1 provides the strength of the surface pressure systems, ITD, CAB and ITCZ displacements, while subsection 1.

2 1.0 GENERAL CLIMATOLOGICAL SITUATION Subsection 1.1 provides the strength of the surface pressure systems, ITD, CAB and ITCZ displacements, while subsection 1.2 is on the troposphere and gives a brief on monsoon and relative humidity thresholds. 1.1 SURFACE Pressure Systems The Azores High of 1033hPa strengthened by 1hPa compared to the previous dekad and by 11hPa with respect to the climatological mean ( ). It was located at 38 N and 20 W, south of its climatological position over North Atlantic Ocean. St. Helena High of 1021hPa strengthened by 1hPa compared to the previous dekad but remained the same as the climatological mean ( ). It was located at 35 S and 05 W, southeast of its climatological position over South Atlantic Ocean. Mascarene High of 1020hPa weakened by 4hPa compared to the previous dekad but had a strength of 6hPa abovd the climatological mean ( ). It was located at 40 S and 42 E, west of its climatological position over Indian Ocean. Thermal Low of 1008hPa remained stable compared to the previous dekad and the same as the climatological mean ( ). It was located at 6 N and 31 E over southern Sudan, northwest of its climatological position. Figure 1. Observed Mean Sea Level Pressure (Contour) and anomaly (shaded) during the period from 21 st to 31 st January, 2018(Source NOAA/NCEP). 2

1.1.2 Inter-Tropical Discontinuity (ITD), Inter-Tropical Convergence Zone (ITCZ) and Congo Air Boundary (CAB) Between the 2 nd dekad and the 3 rd dekad of January 2018, the ITD remained quasi

The CAB remained quasi stationary over western Tanzania, while the ITCZ moved northward by 2 degrees over northern Madagascar (Figure 2).

3 1.1.2 Inter-Tropical Discontinuity (ITD), Inter-Tropical Convergence Zone (ITCZ) and Congo Air Boundary (CAB) Between the 2 nd dekad and the 3 rd dekad of January 2018, the ITD remained quasi stationary over North Atlantic and southern parts of Gulf of Guinea countries and CAR. The CAB remained quasi stationary over western Tanzania, while the ITCZ moved northward by 2 degrees over northern Madagascar (Figure 2). Figure 2: The mean position of ITD, CAB and ITCZ for the 3 rd dekad (black) and 2 nd dekad (blue) of January The red and green triangles represent their maximum and minimum displacements, respectively. 1.2 TROPOSPHERE African Monsoon At 850hPa level (Figure 3a), moderate to strong north westerly winds were observed over Libya, Egypt and Sudan veering to moderate to strong easterlies over Chad, Mali, Mauritania, Algeria, Guinea, Senegal, Niger, Nigeria, Cameroon and CAR. Moderate easterlies prevailed as well over Eastern Africa countries, Zimbabwe, Botswana and South Africa. At 700 hpa level, moderate to strong north westerly winds were observed over Tunisia, Libya and Egypt. Moderate to strong easterlies prevailed over Gulf of Guinea countries, CAR, DRC, Congo, Gabon and Angola, while moderate westerly winds dominated over South Africa and Namibia (Figure 3b). Weak moderate high Weak moderate high 3

4g/m 2 over Morocco, Algeria, northern Niger, eastern Chad, much of CAR and South Sudan. High dust loading ranging between 0.4 to 1.

4 Figure 3a: Mean wind at 850 hpa (m/s) during the period from 21 st to 31 st January, 2018 (Source: NOAA/NCEP). Figure 3b: Mean wind at 700 hpa (m/s) during the period from 21 st to 31 st January, 2018 (Source: NOAA/NCEP) Dust loading particles Figure 4a shows low dust loading ranging from 0.1 to 0.4g/m 2 over Morocco, Algeria, northern Niger, eastern Chad, much of CAR and South Sudan. High dust loading ranging between 0.4 to 1.2 g/m 2 was observed over much of Mali, Senegal, Guinea, Liberia and Côte d Ivoire, southern Ghana and Nigeria, western Cameroon and central Chad. The highest dust loading ranging between 1.2 to 6.4 g/m 2 prevailed over Burkina Faso, southern Niger, northern Ghana, Benin and Nigeria, and western Chad Surface Dust Concentration Figure 4b shows low surface dust concentrations ranging between (5 to 50µg/m 3 ) over northern Morocco, and Algeria, western Libya, central CAR and much of Ethiopia. Moderate concentrations (50 to 200µg/m 3 ) prevailed over much of Mauritania, Egypt, Sudan, South Sudan and Senegal, southern parts of Gulf of Guinea countries and northern Niger. The concentrations of 200 to 500 µg/ m 3 were observed over southern Mauritania, central Mali and Niger, western Burkina Faso, northern Côte d Ivoire, Ghana and Togo. The highest concentrations of above 500 to 2000 µg/ m 3 prevailed over eastern Mali and Burkina Faso, southern Niger, northern Benin and Nigeria, and western Chad. Fig. 4a: Dekadal Dust loading (g/m2) 21 st to 31 st January 2018 (Source: WMO SDS-WAS: BSC-DREAM8b) Fig. 4b : Surface Dust Concentration (μg/m 3 ) 21 st to 31 st January 2018 (Source: WMO SDS-WAS: BSC-DREAM8b) Wind at 200 hpa. During the third dekad of January 2018, strong easterly winds prevailed over North Africa countries, the Sahel, Gulf of Guinea countries, Namibia, Botswana and South Africa at 200hPa. Moderate to weak winds prevailed over the rest of the continent. 4

5 Weak moderate high Figure 5: Mean wind at 200hPa (m/s) during the period from 21 st to 31 st January, 2018 (Source: NOAA/NCEP) Relative Humidity (RH) at 850 hpa At 850hPa level (Figure 6), higher RH values ( 60%) were observed over northern Algeria, Libya and Egypt, southern Gulf of Guinea, much of Central Africa, Uganda, Kenya, Tanzania, Angola, Zambia and Mozambique, South Africa and much of Madagascar during the third dekad of January Low RH values ( 40%) were recorded over North Africa, the Sahel, Namibia and Botswana. The RH anomalies for the third dekad of January 2018 (Figure 6) were positive over most parts of the continent, except over Nigeria, Cameroon, CAR, Ethiopia, Angola, Zambia, Namibia and Botswana where negative anomalies of RH were observed. The anomalies were determined based on the reference period Figure 6. RH (%) at 850hPa (contour) and anomaly (shaded) during the period from 21 st to 31 st January, 2018.(SOURCE/.NOAA/.NCEP-CAR/.CDAS1) Relative Humidity (RH) at 700hPa High RH with values 60% at 700 hpa in Figure 7 were observed over much of Central Africa Eastern Africa and Southern Africa countries. Elsewhere over the continent, RH with values 50% were observed. 5

The RH anomalies for the third dekad of January 2018 (Figure 7) were negative over most parts of the continent, except over Morocco, Algeria, Congo, DRC, South Sudan, Zimbabwe, Zambia, South Africa

6 The RH anomalies for the third dekad of January 2018 (Figure 7) were negative over most parts of the continent, except over Morocco, Algeria, Congo, DRC, South Sudan, Zimbabwe, Zambia, South Africa and Swaziland where positive anomalies were recorded. The anomalies were determined based on the reference period: Figure 7. RH (%) at 700hPa (contour) and anomaly (shaded) during the period from 21 st to 31 st January, 2018.(SOURCE/.NOAA/.NCEP-CAR/.CDAS1) 2.0 PRECIPITATION Figure 6 shows the observed precipitation estimate in percentage of average for the third dekad of January Precipitation Above to well above average precipitation was observed over northern Morocco and Algeria, Gabon, eastern DRC, southern Uganda and Tanzania, much of Zambia, Zimbabwe, Namibia and Botswana, southern Mozambique and northern South Africa. Below to well below average precipitation was observed over northern Tunisia, parts of Congo, western DRC, much of Angola and Madagascar, southern South Africa and northern Mozambique. Details: North Africa: Observed near average precipitation, except over northern Morocco and Algeria where above average precipitation was observed. The Sahel: Observed near average precipitation. Gulf of Guinea countries: Received near average precipitation. Central Africa countries: observed above to well above average precipitation, except over Congo and western DRC where below average precipitation was observed. Eastern African countries: Observed near average precipitation, except over southern Uganda and Tanzania where above average precipitation was observed. Southern Africa countries: Observed above to well above average precipitation, except over northern Mozambique, much of Angola and Madagascar where below average precipitation was recorded. 6

Figure 8: Precipitation in percent of average for dekad 21 st to 31 st January, 2018. The reference period used is 1981-2010. Source: NOAA/.NCEP/.CPC/.FEWS/.Africa/.DAILY/) 3.

1 PRECIPITATION During the period from 7 th to 13 th February 2018 (Figure 9a), low to moderate precipitation is likely over northern Morocco, Algeria and Egypt, southern Congo and DRC, northern

7 Figure 8: Precipitation in percent of average for dekad 21 st to 31 st January, The reference period used is Source: NOAA/.NCEP/.CPC/.FEWS/.Africa/.DAILY/) 3. Outlook valid from 7 th to 20 th February, PRECIPITATION During the period from 7 th to 13 th February 2018 (Figure 9a), low to moderate precipitation is likely over northern Morocco, Algeria and Egypt, southern Congo and DRC, northern Angola and much of South Africa. Moderate to heavy precipitation is likely over southern Tanzania, parts of Mozambique and southern Madagascar. Heavy precipitation is likely over northern Zambia, Malawi, Mozambique and Madagascar. During the period from 14 th to 20 th February 2018 (Figure 9b), low to moderate precipitation is very likely over northern Morocco, southern Gulf of Guinea countries and CAR, parts of South Sudan,, southern Angola, Zambia and Zimbabwe, and eastern South Africa. Moderate to heavy precipitation is likely over eastern DRC, southern Tanzania, northern Zambia and Mozambique. Heavy precipitation is likely over western DRC, northern Angola and Madagascar. Figure 9a: Precipitation forecast from 7 th to 13 th February 2018 (Source: ACMAD) Figure 9b: Precipitation forecast from 14 th to 20 th February 2018 (Source: ACMAD) 3.2 Temperature 7

From 7 th to 15 th January 2018 (Figure 10), normal to positive temperature anomalies are expected over much of Guinea, Côte d Ivoire, Ghana, Nigeria, Cameroon, CAR, Sudan, South Sudan, Uganda,

Figure 10: Temperature Anomaly forecast from 7 th to 15 th February, 2018 (Source: COLA) 3.

8 From 7 th to 15 th January 2018 (Figure 10), normal to positive temperature anomalies are expected over much of Guinea, Côte d Ivoire, Ghana, Nigeria, Cameroon, CAR, Sudan, South Sudan, Uganda, Kenya, Namibia and Botswana. Normal to negative anomalies are expected over Tanzania, Madagascar, Malawi, Zimbabwe, Angola, Zambia and Mozambique. Figure 10: Temperature Anomaly forecast from 7 th to 15 th February, 2018 (Source: COLA) 3.3 Soil Moisture The outlook of the variation in soil moisture (Figure 11) shows that an increase in soil moisture is expected over southern Nigeria, parts of DRC and Congo, much of Angola, Mozambique, Zambia, South Africa, Zimbabwe, Madagascar, Swaziland and Malawi. Figure 11: Soil moisture change for the period from 7 th to 15 th February, 2018 (Source: COLA) 8

African Centre of Meteorological Applications for Development Centre Africain pour les Applications de la Météorologie au Développement

African Centre of Meteorological Applications for Development Centre Africain pour les Applications de la Météorologie au Développement Ten Day Climate Watch Bulletin N 34 Dekad 1 st to 10 th December,