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West Africa Seasonal Monitor: August 29, 2021

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Despite a late start the Sahel seasonal rainfall is mostly average to above-average and well distributed

KEY MESSAGES

There are clear signs the Intertropical Front (ITF) has reached its northernmost position during the last couple of dekads. Its southward retreat is expected to start soon.

• Heavy rainfall of above 200 mm has affected large areas in southwestern Mali, the western half of Guinea, and western Sierra Leone raising flooding concerns.

• Persistence of dryness around Lake Chad area and extending into Far North Cameroon, is likely to have negative consequences on crops and pastures production

UPDATE ON SEASONAL PROGRESS

• The ITF is located between 16.5 degrees of latitude north in eastern Chad to 21.3 degrees in Mauritania as of the end of the second dekad of August around its climatological position over most of the region (Figure 1). For the last three dekads the Intertropical Front (ITF) has been going back and forth around the same position throughout its regional extent. Considering the warm current and forecast Gulf of Guinea SSTs, this is an indication that the ITF has reached its northernmost position for the current season. Its southward retreat is expected soon.

• The delayed ascent of the ITF this season has resulted in rainfall deficit that persisted over 2 large portions of the Sahelian zone till mid-July. This early season Sahelian deficit areas included an area covering Niger, northern Nigeria and extending into western Chad and another one in the extreme western Sahel extending from eastern Senegal into central southern Mauritania. Beginning from mid-July, the rainfall situation over the region has improved resulting in a significant decline in the rainfall deficits. The seasonal cumulative rainfall from May 1st to August 25 (Figure 2) has been above average over most of the region. However, negative impact of dryness on crop and pasture development over areas where dryness has persisted for a very long time such as Far North Cameroon and Lake Chad is expected.