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Uneven rainfall improves rangeland resources but reduces cropping prospects in eastern Horn

  • Seasonal Monitor
  • East Africa
  • December 19, 2020
Uneven rainfall improves rangeland resources but reduces cropping prospects in eastern Horn

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  • Key Messages
  • Key Messages
    • The ongoing short rains/deyr season has been characterized by a mixed onset of rains in the eastern Horn, ranging from an early and average onset in parts of Somalia and Ethiopia to a delayed/failed season in other parts of Somalia and Kenya. However, at the peak of the rainfall season in November, unexpected episodic rainfall events, including Cyclone GATI, helped ease some early season rainfall deficits.

    • Overall, the improved seasonal rainfall performance over the eastern Horn has largely benefited rangeland resource replenishment of pasture and surface water, particularly among the pastoral and marginal agropastoral communities. However, crop yield prospects in most marginal agricultural areas in the eastern Horn are expected to be below-average due to significantly delayed and poorly distributed rainfall, localized flooding, and desert locusts.

    • Most parts of the region's western sector had well distributed, average to above-average short-rains performance, with expected favorable crop production prospects, despite some areas reporting localized flooding or cumulative rainfall deficits.

    • An early to a timely cessation is expected in areas that rely heavily on the short-rains season, as the rains get fully established in Tanzania. However, tropical cyclone activities are also likely to continue influencing episodic rainfall storms over parts of the eastern coastal regions and surrounding areas.


    Cumulative rainfall through early December for the short rains/deyr season was largely characterized by a mixed start, followed by erratic rainfall distribution coupled with long dry spells and hotter-than-normal land surface temperatures (LST) over the eastern Horn. In November, the eastern Horn received several episodic, abnormally heavy rainfall events attributed to changes in the Indian Ocean Dipole (IOD). The IOD shifted from negative in August/September to its current neutral status in October, which is more conducive to near-normal rainfall performance over the eastern Horn. Additionally, the passing of a strong easterly Madden Julian Oscillation (MJO) wave in mid-to late-November contributed to better-than-anticipated rainfall performance. This resulted in a series of heavy rainstorms from mid-October into November, which eased seasonal rainfall deficits in parts of southern and southeastern Ethiopia; northeastern, central, and southern Somalia; parts of southeastern Kenya; and northeastern and central Tanzania. Much of Somalia also observed near-average rainfall amounts in November, while southern and southeastern Ethiopia, southwestern Somalia, and northeastern and eastern Kenya experienced significant rainfall deficits. Meanwhile, above-average rainfall fell across much of the southern South Sudan; northern and eastern Uganda; western, southeastern, and Kenya's coastal strip; along with Rwanda and Burundi. For much of western East Africa, the seasonal rains from September through early December were generally stable and favorable for agricultural production systems, apart from localized flooding in parts of northeastern Uganda. Meanwhile, parts of the western regions of Uganda bordering eastern DRC maintained significant rainfall deficits through this period. In late November, a category two tropical cyclone (GATI) led to unprecedented heavy rains and strong winds over northeastern and central Somalia. In parts of the northern Somali region in Ethiopia, GATI's impacts were generally less severe and largely beneficial to pasture and water resources. The development of the MJO, tropical cyclone events, and their associated impacts are mostly unpredictable at seasonal to monthly timescales but can be forecast and monitored at sub-seasonal timescales, as often reported weekly by partners at NOAA/CPC, CHC, and NASA. 

    In parts of the eastern Horn, heavy rains following the development of the MJO contributed significantly to improved pasture and surface water resources, particularly in Somalia, southern and southeastern Ethiopia, and northern Kenya. Pasture and browse recovery following these seasonal rains resulted in greener-than-normal vegetation conditions, contrary to early season expectations (Figure 2). However, there remain localized areas of drier-than-average vegetations, particularly in western Ethiopia and southern and central Sudan. These and other local current anomalously poor vegetation conditions are likely driven by the combined effects of below-average rains from June through September and sustained high land surface temperatures (LST) for the past couple of months. In addition, the ongoing desert locust upsurge in Ethiopia, where locusts are present in southern pastoral areas, and north-central Somalia has contributed to localized vegetation deficits. In western East Africa, near-normal vegetation conditions are visible, especially in Uganda, Rwanda, and Burundi. Due to the earlier-than-normal southward progression of the main tropical rainfall system, parts of Tanzania, particularly its southern and eastern regions, are experiencing greener-than-normal vegetation conditions.

    The latest available crop assessment reports and satellite-derived crop models indicate cropping conditions over southern Somalia, eastern and southeastern Kenya, and the northeastern regions of Tanzania range from failure to very good. However, the expected cessation of seasonal rains in December is likely to drive crop-water-stress and stunted/wilting outcomes for the maize crop, significantly reducing yields. Additionally, the desert locust invasion from Somalia and eastern Ethiopia into Kenya in December is likely to result in crop damage and loss, which may negatively impact Kenya's short rains harvest in February 2021. Meanwhile, average to slightly above-average maize harvests are expected across Kenya's western and central counties and much of Uganda, Rwanda, and Burundi. However, localized flooding due to persistent above-average rains in parts of Bundibugyo and Ntoroko districts in the Western Region of Uganda resulted in flooding, which is expected to impact crop conditions and the harvest negatively.

    The following is a country-by-country update on recent seasonal progress to date:

    • In Somalia, the deyr rains are generally below average in the northern and far southern regions and near average in most south-central regions. Despite an erratic start of the season, rainfall performance improved significantly from late October into November, mostly benefiting rangeland resources in central Somalia. On the other hand, the cropping season's quality is mixed in key sorghum and maize cropping zones in southern Somalia, ranging from good to mediocre. Crop production is likely to be below average due to the anticipated cessation of seasonal rains in December at critical crop vegetative to reproductive stages, erratic rainfall distribution in agropastoral areas, and prolonged flooding in riverine areas damage from desert locusts. Additional crop damage from desert locust is likely, as they are anticipated to migrate southwards from northern and central Somalia in December. Meanwhile, northeastern Somalia and neighboring areas received unprecedented rainfall and strong winds from cyclone GATI in late November, which caused flash floods resulting in crop, livestock, and property losses, particularly in the Iskushuban district of Bari region. According to OCHA, approximately 120,000 people were affected, including the displacement of around 42,100 people.
    • In Ethiopia, despite favorable June to September kiremt rainfall in western Ethiopia, below-average to slightly below-average meher harvest is likely due to limited access to agricultural inputs and crop damage from flooding and desert locusts. Meanwhile, parts of the southern and southeastern pastoral zones are experiencing below-average deyr seasonal rains and drier-than-normal vegetation conditions. In southern pastoral areas, despite heavy rainfall in October, below-average rainfall in November and early December, increased rainfall deficits will likely lead to earlier than normal pasture losses and sparse pasture in some areas until the Gu.
    • In Kenya, the October-December short rains started in mid-to late-November, approximately 20-30 days late in parts of eastern and southeastern Kenya. These areas rely heavily on timely seasonal rains for crop production. Although there has been an improvement in cumulative rainfall into early December, crops are mostly in the emerging to early vegetative stages. With the anticipated cessation of rains in December, crops, particularly maize, are likely to be stunted/wilted. Additionally, the expected invasion of desert locusts in December increases the risk for further crop damage and loss. Overall, maize production prospects are precarious in marginal agricultural areas. In contrast, the erratic but at times heavy rains have driven greener-than-normal vegetation conditions in pastoral areas and have replenished surface water pans and seasonal rivers. However, due to poor temporal distribution of rainfall, there are localized areas of drier-than-normal vegetation conditions in Marsabit, Garissa, and Moyale counties. In western Kenya, rainfall has remained above-average through the short rains season. The main harvest, which is concluding, is estimated to be near average and comparable to 2019.
    • In Sudan, the millet, sorghum, and cash crop harvest is ongoing and expected to be average following average to above-average rainfall from June through September, despite constraints on farmers' ability to purchase farm inputs and hire farm labor and equipment during the prevailing macro-economic crisis. However, devastating floods in August and September damaged crops, particularly sesame, and led to the late replanting of sorghum to recover lost crops across eastern Sudan. The late-planted crops are likely to be harvested in December and early 2021 supporting an average national harvest. 
    • In South Sudan, the main rainfall season from June to September was extended into October. Since July, many riverine and low-lying areas have experienced severe floods, especially along the White Nile River. Some of the worst flood-affected areas include Bor South, Twic East, and Greater Pibor Administrative Area in Jonglei state and Mayendit in Unity state. Conversely, below-average rainfall contributed to poor crop performance in localized areas in Northern Bahr el Ghazal state. Fall Army Worm also damaged second-season maize in Magwi, Pageri, and Mugali areas of Eastern Equatoria state and Twic, Gogrial East, and Gogrial West of Warrap state. In other areas in Greater Equatoria and Western Bahr el Ghazal, favorable rainfall has provided favorable conditions for main season crops. Overall, 2020 crop production is expected to range from below to near the 2019 average and near the five-year average on the county level.
    • In Uganda, most farmers engaged in earlier-than-normal planting activities in northern, eastern, and central Uganda with the start of the August to November second rainy season. Favorable cropping and rangeland conditions have been maintained across the country. However, persistent and well above average rainfall in parts of Bundibugyo and Ntoroko districts in the Western Region resulted in flooding, causing significant crop and property losses resulting in locally below-average crop production. Nationally, the second season harvest is estimated to be comparable to 2019 and slightly better than the five-year average.
    • In Rwanda and Burundi, Season A rains from September to December were delayed in parts of northern and western Rwanda and the Eastern Lowlands and Imbo Plains in Burundi. However, cumulative performance gradually improved to near-average to above-average levels as the season progressed. In contrast, an earlier-than-normal onset and above-average rainfall performance occurred in the rest of Rwanda and Burundi. The maize crop is presently between the late vegetative to reproductive stages, with rains forecast through this critical phenological stage. Overall, the harvest is expected to be average and similar to 2019.
    • In Yemen, weather conditions in November through early December were typically sunny and dry in most areas. However, the development of tropical cyclone GATI over the Arabian Sea resulted in moderate to heavy rains over Yemen's southern coastal areas. More light to moderate rainfall is forecast for the western highland regions, which will likely enable further desert locust breeding. The dry season is expected to continue across the rest of the country.


    According to the short-term rainfall forecast through December 21, there is an increased likelihood of unseasonal light to moderately heavy rainfall over Yemen, northeastern Somalia, and parts of Afar and Tigray regions of Ethiopia, particularlytowards the end of December. Many areas in the eastern Horn of Africa are likely to be atypically sunny and dry apart from Kenya's southeastern and coastal regions (Figure 3).

    The anticipated timely to early cessation of the short-rains season in December is likely to adversely affect the maize crop in early vegetative stages, especially in southern Somalia and eastern Kenya.  Unlike the 2019 desert locust invasion, which occurred during maize maturation and close to harvest, the forecast southerly winds are likely to drive a large-scale desert locust invasion towards areas with immature crops. The forecast locust invasion

    It is likely to be more extensive and damaging compared to late 2019, impacting the crop harvests and pasture/browse for livestock in areas that heavily rely on the October-December rainfall season.

    A review of the cumulative rainfall performance for October through December, together with the forecast cessation of rainfall, depicts the impact of a below-average short rains/deyr season across much of the Horn of Africa (Figure 4). Much of the northeastern Somali region of Ethiopia and parts of northwestern Somalia are experiencing 50-80 percent below average seasonal rainfall. These areas are likely to be the worst-affected by the poor short rains/deyr. Similarly, the far southern areas of Somalia and northeastern and eastern Kenya are also likely to experience below-average rainfall performance as the short rains season comes to an early end.

    However, South Sudan, south Ethiopia, Uganda, northwestern and western Kenya, Rwanda, and Burundi are likely to observe 80 to 150 percent of average rainfall, with parts of northeastern and eastern Uganda and western Kenya forecast to maintain over 150 percent above average cumulative rainfall. Tanzania is expected to maintain average to above-average rainfall as its main rainfall season intensifies in the central and southern regions.

    The current climate drivers of La-Niña, neutral IOD, and western Pacific warm pool are likely to drive below average March-May seasonal rains over equatorial East Africa, particularly over the eastern Horn.

    Figures Map of CHIRPS preliminary rainfall anomalies (mm) compared to the 1981-2010 average, October 1-December 25, 2020.

    Figure 1

    Figure 1.

    Source: UC Santa Barabara Climate Hazards Center

    Map of /NDVI as a percent of the median of 2003 - 2017, December 1-10, 2020 . 

Greener-than-normal vegetation conditions i

    Figure 2

    Figure 2.

    Source: FEWS NET

    Map of GEFS rainfall forecast in mm, valid between, December 15 - 21, 2020. Many areas in the eastern Horn of Africa are like

    Figure 3

    Figure 3.

    Source: NOAA/CPC

    Map of CHC Early Estimate for October 1 – December 25, 2020, expressed as percent normal (%) from the 1981-2018 average. Base

    Figure 4

    Figure 4.

    Source: UC Santa Barbara Climate Hazards Center

    FEWS NET’s Seasonal Monitor reports are produced for Central America and the Caribbean, West Africa, East Africa, Central Asia, and Somalia every 10-to-30 days during the region’s respective rainy season(s). Seasonal Monitors report updates on weather events (e.g., rainfall patterns) and associated impacts on ground conditions (e.g., cropping conditions, pasture and water availability), as well as the short-term rainfall forecast. Find more remote sensing information here.

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