Large dust cloud over Sahel
11 April 2015 12:00 UTC–12 April 12:00 UTC
Large parts of Africa's Sahel were covered by dust in the second week of April.
15 September 2022
11 April 2015
By Diakaria Kone (EAMAC)
On 11 April dust was lifted over parts of Sahel due to an increase of surface winds (over 27km/h), at the same time as a developing depression off the coasts of Morocco and Portugal (Figure 1 and 2).
During the evolving dust event over a large area of Sahel, analysis and forecasts charts were closely followed to see if it would become an even larger event.
This was not only because of the widespread dust, but also because of the sharp boundary between the dry, dusty air in the north and the moist air further south.
This can be clearly seen on Figure 1, the dry-dusty air appears as red and the moist air as dark blue.
On 12 April the area the dust covered increased considerably, as can be seen in Figure 2 and 3.
The full evolution of the dust event can also be clearly seen in the Dust RGB animation from 9 April 00:00–13 April 16:00 UTC.
At the time there was a low probability that this dust event could affect most of the Gulf of Guinea regions, particularly western parts — taking into consideration the straight easterly or even south-easterly winds at 925hPa, as seen on the analysis and forecasts charts from Météo-France.
A depression, previously located off the coasts of Morocco and Portugal, was also monitored, but it was considered likely to move south-eastwards and bring rain over southern regions of western Sahel, such as South Burkina, Mali and the north and south Gulf of Guinea regions.
The system was predicted to gradually move over eastern Sahel, but not to affect these regions the same way due to the current low position of the Inter-tropical discontinuity (ITD) (the boundary between the moist southwesterly monsoon flow and the hot, dry northeasterly wind from the Sahara).
