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Heavy rains continue in Tanzania; rainfall deficits strengthen in western areas

  • Seasonal Monitor
  • East Africa
  • February 29, 2016
Heavy rains continue in Tanzania; rainfall deficits strengthen in western areas

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  • Key Messages
  • Seasonal Progress
  • Forecast
  • Key Messages
    • Rainfall over the past 30 days has been below average in western areas of East Africa, as the January rains subsided in February, including over parts of Uganda, Rwanda, and western Kenya.

    • The ongoing strong El Niño even continues to drive above-average rainfall over much of Tanzania, with production prospects remaining favorable for the main agricultural season.

    • Seasonally sunny and dry conditions have also continued over the Eastern Horn. Coupled with hotter-than-normal land surface temperatures, these conditions continue to result in the decline of already limited rangeland (water and pasture) resources. 

    • Rainfall forecasts for the next one to two weeks indicate an increased likelihood for rainfall to be erratically distributed over Belg-cropping areas in Ethiopia, and over parts of Tanzania, Rwanda, Uganda, and Kenya.


    Seasonal Progress

    Overall, rainfall performance was mixed in the region over the past 30 days, with Tanzania continuing to receive well above-average rainfall (50 to 500 mm above normal), while western areas of the region, including Uganda, Rwanda, and western Kenya received significantly below-average rainfall (Figure 1). The on-going above-average rains over Tanzania are being driven by the continued presence of a strong El Niño event and tropical depression activities off the Madagscar/S.Tanzania coastal strip areas. Meanwhile, the eastern Horn remained typically dry, but hotter-than-average temperatures are resulting in the continued decline in availability of already limited rangeland resources (water and pasture) for much of the predominantly pastoral areas of Somali region of Ethiopia, central and northeastern Somalia, and northeastern Kenya.

    For the early planted short-cycle crops in parts northeastern Amhara and Tigray, the unseasonal rains in January decreased in February, resulting in water stress for crops during the past couple of weeks. Meanwhile, pastoral areas of northern and eastern Ethiopia, Djibouti, and northern Somalia have remained generally dry and hot, with parts of western Afar region having slightly better-than-normal rangeland conditions following rains in January.

    Despite the recent decrease in rainfall along equatorial areas of the region, current vegetation conditions have significantly improved compared to the long-term average (2001/10) in parts of southern and central Somalia, southwestern Ethiopia, southeastern to western Kenya, much of Uganda, and over southern and eastern Tanzania, according to NDVI (Figure 2). Meanwhile, expansive areas of drier-than-average vegetation conditions (in dark-brown shade) are shown in South Sudan, indicative of rapidly deteriorating vegetation conditions. These areas will require close field monitoring to ascertain their worsening situation and as the rainfall outlook for the coming weeks indicate continued dry weather. 


    Forecast

    Short-term rainfall forecasts for the next one to two weeks (NOAA/GFS) indicate an increased likelihood for moderate to heavy rains (25 – 100 mm) over much of southern and central Ethiopia, northern Somalia, Kenya, western Tanzania, Burundi, Rwanda, and western Uganda (Figure 3). The forecast rains are expected to be erratic in terms of their spatial and temporal distribution for the forecast period. This erratic pattern is attributed to the on/off tropical depression activities in the neighbouring Indian Ocean and could possibly result in an erratic onset of rainfall for the March – May seasonal rains over much of eastern Horn.

    Figures Figure 1. 30-Day ARC2 RFE Anomaly, January 23-February 21, 2016, compared to average (1983-2009)

    Figure 1

    Figure 1. 30-Day ARC2 RFE Anomaly, January 23-February 21, 2016, compared to average (1983-2009)

    Source: NOAA/CPC

    Figure 2. eMODIS/NDVI, for January 16-25, 2016 compared to average (2001-2010).

    Figure 2

    Figure 2. eMODIS/NDVI, for January 16-25, 2016 compared to average (2001-2010).

    Source: USGS/FEWS NET

    Figure 3. GFS Rainfall Weekly Forecast (mm), valid up to February 29, 2016

    Figure 3

    Figure 3. GFS Rainfall Weekly Forecast (mm), valid up to February 29, 2016

    Source: NOAA/CPC

    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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