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Favorable September rainfall; average to above-average harvest likely for most of the Sahel

  • Seasonal Monitor
  • West Africa
  • October 22, 2014
Favorable September rainfall; average to above-average harvest likely for most of the Sahel

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  • Key Messages
  • Update on Seasonal Progress
  • Forecasts
  • Partner
    USGS
    Key Messages
    • Despite a delayed start to the rainy season, average to above-average harvests are expected for most of the Sahel due in part to continued favorable rainfall conditions at the end of the rainy season in September.  

    • However, rainfed crop yields and pastoral conditions are expected to be well below average over much of Senegal and Mauritania, as well as over other localized areas in the region, due to the combined effects of a late onset and poor rainfall conditions throughout the season.

    • The rainy season is continuing normally over much of the Guinean-Sudanian and Bi-modal zones. In these areas, cumulative seasonal rainfall totals vary from well above-average to moderately below-average, depending on the locality. However, even in areas that experienced rainfall deficits, crops continue to develop normally as rainfall levels have been sufficient to meet crop water requirements.


    Update on Seasonal Progress
    • The Intertropical Front (ITF)1 began its on-time retreat southwards starting in late August. From Mali to Chad, it was consistently about or north of its average position, contributing to an extension of the rainy season in many pastoral areas and above-average rainfall over most of the region in September. However over Mauritania, the ITF has remained slightly south of its seasonally average position.
    • While cumulative rainfall totals during the month of September were generally average to above-average, rainfall deficits were observed in certain localized areas (Figures 1 and 2). These deficits mostly ranged from light to moderate except for the following areas where deficits were severe: 1) the extreme southeastern Diffa region of Niger and northeastern Borno State of Nigeria; 2) the central Tahoua region of Niger and southern Kidal region of Mali; and 3) northern Senegal and southern Mauritania.
    • Rainfall conditions during the month of September had the following impacts on crop development and pastoral conditions across the region:
      • In the Bi-modal zone, rainfall was in most areas above-average and well distributed in time, providing adequate moisture for normal second season crop development. 2014/15 crop production in this zone is expected to be average to above-average.
      • In the Guinean-Sudanian Zone, crop water requirements continue to be met, including areas where below-average cumulative rainfall occurred. Consequently, this year’s crop harvests are expected to be average to above-average, with the exception of areas worst-affected by Ebola in Guinea, Liberia, and Sierra Leone. In these areas, fears about contracting Ebola have disrupted crop production activities, and harvests could be locally below-average, despite favorable rainfall conditions.
      • In the Sudanian-Sahelian zone, the generally average to above-average September rainfall resulted into adequate moisture for continued crop growth over most of the zone. This particularly benefited crops and pastures in areas where a delayed start to the rainy season caused growth to be behind schedule. In addition, as shown by the NDVI seasonal maximum anomaly (Figure 3), even many areas where September rainfall was below average showed good vegetative biomass, likely due to the combined effects of a relatively good temporal distribution of the September rains and residual moisture from above-average rainfall in August. Exceptions to this, however, are shown by areas circled in red in Figure 3 and include:
        • Northern Senegal and southern Mauritania, where severe rainfall deficits in September, along with long planting delays at the beginning of the season, negatively impacted crop and pasture development to date. A significant drop in crop yields, below-average rainfed crop harvests, and poor pasture development are, therefore, expected.
        • Localized pockets through the region (Lake Chad area, eastern Burkina Faso; western Niger; southeastern Hodh el Chargui in Mauritania; southwestern and southeastern Timbuktu and northern parts of Mopti and Segou regions in Mali), where below-average rainfall for extended periods of time between June and September resulted in delayed planting activities and/or crop and pasture development.

    1 Inter-Tropical Front (ITF): The separation line, at ground level, between cool, moist monsoon air from the south and hot, dry air from the north.


    Forecasts
    • According to the short and medium term forecasts from NOAA/CPC, the rainy season is over in the Sudanian-Sahelian zone.
    • The early October 2014 NOAA-CPC Northern American Multi-Model Ensemble seasonal forecast for the period of November 2014 to January 2015 has no skill over the Bi-Modal and southern part of the Guinean-Sudanian zones. The rainy season normally ends in November or early December in these zones.
    Figures Seasonal calendar in a typical year

    Figure 1

    Seasonal calendar in a typical year

    Source: FEWS NET

    Figure 1. Total rainfall estimate (RFE) in mm, September 2014

    Figure 2

    Figure 1. Total rainfall estimate (RFE) in mm, September 2014

    Source: USGS/FEWS NET

    Figure 2. Rainfall estimate (RFE) anomaly compared to the 2005-2009 mean, September 2014

    Figure 3

    Figure 2. Rainfall estimate (RFE) anomaly compared to the 2005-2009 mean, September 2014

    Source: USGS/FEWS NET

    Figure 3. NDVI seasonal maximum anomaly in % of 2001-2013 average

    Figure 4

    Figure 3. NDVI seasonal maximum anomaly in % of 2001-2013 average

    Source: USGS/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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