Rainfall has been erratic over the eastern Horn of Africa

• Erratically timed rains fell across the eastern Horn in early April. In the western sector of the region, cumulative rainfall remained below average in most areas.

• Very heavy, torrential rains over Tanzania’s coastal strip, especially over Dar es Salaam from April 12 to 14 and over Morogoro Region led to floods. Short-term forecasts suggest the possibility of further flooding.

• Vegetation and crop conditions have gradually improved in response to the start of the rains in many areas. However, in localized areas in the eastern sector and in the southern Belg-cropping areas in Ethiopia, total rainfall since March has remained below average.

Over the past two weeks, very heavy rains from tropical storms have resulted in floods in northeastern, coastal areas in Tanzania. Rains were over 150 millimeters (mm) in some places with even heavier rains in areas that have flooded in and around Dar es Salaam and Morogoro regions since late March. These floods damaged property and public infrastructure, leaving many without shelter and resulting in at least 15 fatalities in flooded areas.

While this very heavy rain was observed in northeastern Tanzania, in much of eastern Horn of Kenya including southern Somalia and eastern Ethiopia, rainfall was erratic in terms of timing with only light to moderate volumes. Some areas had dry spells in late March and early April. Since the beginning of the season in March, cumulative rainfall has been below average in parts of southern Somalia and neighboring areas in eastern and central Ethiopia. Despite the erratic rainfall, the eMODIS Normalized Difference Vegetation Index (NDVI) shows some vegetation has responded to the rains, at least in part due to crop growth in parts of southern, central, and northern Kenya, eastern and southern Ethiopia, and Tanzania (Figure 2).

The March to May long rains/first rainy season in Uganda/season ‘B’ in Rwanda and Burundi had a near-normal onset between February and early March in the western sector of the region including Rwanda, Burundi, Uganda, and the Greenbelt of South Sudan. Vegetation as measured by NDVI has responded in South Sudan’s Greenbelt. Despite mostly normal rainfall amounts over the past two weeks, cumulative rainfall is still below average in parts of Uganda, parts of the Rift Valley in Kenya, Rwanda, and Burundi (Figure 1). Some of the lowest vegetation levels, as measured by NDVI can be found in Uganda and other areas surrounding Lake Victoria in Kenya and Tanzania along with Rwanda and Burundi. Crops are presently mostly in the vegetative stage. Thus far there have not been noticeable adverse effects of the erratic rainfall on crops in western Kenya, Uganda, Rwanda, and Burundi.

Despite a somewhat late start of the rains in some of the northern receiving areas in Amhara and Tigray Regions and in eastern Oromia, Belg crop planting in Ethiopia has had fairly good coverage so far, and most of the crops are developing. However, February to May Belg rainfall has been below average in the southern receiving areas in Southern Nations, Nationalities, and Peoples’ Region (SNNPR). Belg rainfall amounts were also below average from April 11 to 20 in eastern Amhara and Tigray.

The short-term rainfall forecasts for the next two weeks indicate moderate to heavy rains are likely to continue over the western sector of the region in Rwanda, Burundi, Uganda, and western and central Kenya (Figure 3).

However, tropical storms over coastal areas in Tanzania will likely result in more heavy rainfall (Figure 3). These storms will most likely continue to disrupt the overall rainfall performance over the eastern Horn, as they have in the past month. In the eastern Horn, erratically distributed and are mostly light to moderate rain should continue for the rest of April. However, a few localized areas may receive episodic, very heavy rain, most likely to be found over the highlands over the northern Tanzania, central Kenya, and Ethiopia.

May to June is often the peak rainfall period over coastal areas of eastern African. Heavy rain at this time is still likely to occur, according to the latest long-term and medium-term forecasts.