It’s that time of year again when cold air from the mid-latitudes surges into the tropics. The effect in Africa is a strong east to northeast wind from the Chad basin to Mauritania and northern Gabon called the Harmattan.
Harmattan winds blow west to southwestward from the Sahara, with enough strength to carry desert sand and dust to the Atlantic Ocean. This occurs during the boreal winter as deep-layer troughs move across southern Europe and the Mediterranean, penetrating the Sahara. The preceding cold front often loses its identity over the desert due to intense surface heating and mixing. However, the warmed polar air continues moving southward into the Gulf of Guinea.
Harmattan winds become amplified as strong high pressure builds behind these troughs. If the high reaches the southern Sahara, Harmattan winds are likely to extend to the Atlantic coast. Saharan dust carried by the Harmattan reduces visibility to 2-4nm, covering areas offshore in a cloudy haze, and in severe cases reduce visibility to a few meters. These conditions often last for days and become paralyzing when visibility approaches zero, halting flights, increasing risk of flu and asthma, and delaying the wet season for farmers.
To improve planning during the Harmattan season, our meteorologists incorporate advanced, high-resolution dust data, specialized satellite imagery, and upstream surface observations to provide warning days in advance of potentially harmful events.