Kenya: Weather Outlook for the March-May 2011 'Long-Rains' Season

Situation Report
Originally published


  1. Highlights

Performance of the 2010 "Short Rains" (October to December) season

• The October-December "Short-Rains" 2010 rainfall was highly depressed over most parts of the country except the western highlands, parts of the central Rift Valley and Nairobi area where near average rainfall was recorded. This was mainly attributed to the prevailing La Nina conditions in the eastern and central equatorial Pacific Ocean which has an influence of weather over Kenya through tele-connections. Rainfall Outlook for the 2011 "Long Rains" (March to May) Season

• La- Niña conditions (unusually cool sea surface temperatures) continue to be evident over the eastern and central equatorial Pacific Ocean.

• The Indian Ocean Dipole is somehow weak though the western part is neutral while eastern part is relatively cold

• The outlook for March to May 2011 indicates that:

  • Much of the country is expected to record below normal (depressed) rainfall during the "Long Rains" (March to May) Season in 2011;

  • A small portion within the Lake Victoria Basin and the south Coast are likely to realize near normal rainfall tending to above normal (enhanced);

  • Much of the Rift Valley as well as central highlands and Nairobi area are expected to record near normal (average) rainfall; and

  • The rainfall expected in the country is likely to be poorly distributed both in time and space over much of the country especially in the Arid and Semi-Arid Lands (ASALs).

• The Sea Surface Temperature Anomalies over the Ocean Basins are analogous (similar) to those in 2008. Consequently, the distribution of the rainfall for March- April- May (MAM) 2011 Season is likely to be poor with below normal rainfall in March and May and near normal (average) rainfall in April.