March to May (MAM) constitutes an important rainfall season over the equatorial parts of the Greater Horn of Africa (GHA) region. The regional consensus climate outlook for the March to May 2013 rainfall season indicates increased likelihood of near normal to above normal rainfall over southwestern parts of the northern sector as well as the western parts of both the equatorial and southern sectors of the sub-region. Increased likelihood of near normal to below normal rainfall is indicated over the rest of the region. Key among the processes considered in this outlook were the sea surface temperature anomalies over the tropical global oceans with special reference to the Indian Ocean including the Indian Ocean Dipole (IOD), the Atlantic Ocean, monsoonal wind systems and tropical cyclone activities over Indian Ocean sub region, among others.
The outlook is relevant only for seasonal time scales and relatively large areas. Local and month-to-month variations might occur as the season progresses. For example episodic heavy rainfall events leading to flash floods might occur in areas with increased likelihood of near normal to below normal seasonal rainfall.
Additionally dry spells may occur in areas with increased likelihood of near normal to above normal seasonal rainfall. Some of these dry and wet spells are linked to random weather events and cyclones that might evolve suddenly during March and April with indirect impacts in the region. Regional forecast updates will be provided by ICPAC while National Meteorological and Hydrological Services will provide detailed National Updates.