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Above average and well-distributed rainfall over most of the region

  • Seasonal Monitor
  • West Africa
  • October 23, 2020
Above average and well-distributed rainfall over most of the region

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  • Key Messages
  • Update on Seasonal Progress
  • Forecasts
  • Key Messages
    • The Intertropical Front (ITF) southward retreat (Figure 1) is progressing with a slight delay from eastern Mali to Chad but timely in southern Mauritania and northern Senegal.

    • The 2020 growing season has been characterized by mostly average to above average and well-distributed rainfall.

    • The Senegal-Mauritania border suffered from uneven rainfall distribution in the first half of the season but has recovered (Figure 2) due to rainfall improvement starting in September.


    Update on Seasonal Progress
    • The ITF’s southward retreat that started in early September continues; it is currently between 15 and 17 degrees of latitude in early October (Figure 1).  It is around its climatological position in southern Mauritania and northern Senegal but about a couple of degrees north of its normal position from eastern Mali to Chad.  This is a clear indication the end of the rainy season has already started in the area north of the ITF, including in the agro-pastoral part of the Sahel.  However, it is expected to fluctuate around its climatological position before its complete annual retreat.  Therefore, there is still a chance for a few rainfall events, even in the northern part of the Sahel.
    • Throughout the current rainy season, the region has received mostly average to above-average rainfall.  Very few localized areas experienced dryness.  Rainfall deficits mainly were light to moderate and short-lived except in the border region between northern Senegal and southern Mauritania and in the bimodal zone where deficits were more severe and persisted for a while. The heavy rainfall recorded over most of the region from late August to early September and the high soil moisture have caused flooding in many places, particularly along the major rivers.  However, globally the seasonal rainfall has been characterized by a good distribution, which has resulted in favorable moisture conditions for planted crops despite crop damage in flooded areas. Soil moisture and rivers’ flows have also been normal to above normal, which augurs good off-season cropping activities such as recessional and irrigated agriculture and market gardening.
    • Based on the good vegetation performance (Figure 2), the western Sahel, Senegal-Mauritania border region, the August dryness has not hampered the vegetation growth and development in any significant way.
    • The July and August dryness in the bimodal zone resulted in a significant increase in the duration of the minor dry season.  However, from early September to date, the rainfall situation has significantly improved, providing a good prospect for a good outcome of the minor cropping season.

    Forecasts
    • According to NOAA-CPC Northern American Multi-Model Ensemble (NMME) seasonal forecasts for November, there is an increased chance for above-average rainfall over the bimodal zone.
    Figures

    Figure 1

    Source: NOAA

    Figure 2

    Source: NOAA/USGS/FEWS NET

    West Africa seasonal calendar  In the North, Main season cultivation is from mid-May to mid-August. Main harvest is from mid-

    Figure 1

    SEASONAL CALENDAR FOR A TYPICAL YEAR

    Source: FEWS NET

    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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