This seems to be the latest phenomenon. Responsible for widespread floods in east Africa that have killed scores of people. Not sure if it's also causing the drought here

"The extreme weather is blamed on the Indian Ocean dipole, a climate system defined by the difference in sea surface temperature between western and eastern areas of the ocean. The ocean off east Africa is far warmer than usual, resulting in higher evaporation resulting in rain over the continent."

https://www.theguardian.com/world/2019/nov/23/kenya-landslides-kill-29-as-homes-swept-a...