West African Monsoon 2012

Rosalind J Cornforth

doi:10.1002/wea.2161

Abstract

Living up to its reputation as a highly variable climate system, the West African Monsoon (WAM) 2012 contrasted strikingly with the previous year. In 2011, the West African rainy season was delayed, patchy, and irregular. In 2012, whilst it was anomalously wet in many area, the Guinea coastal countries and some crucial agricultural regions remained very dry, persisting from the previous year. As a result, 2012 generated the third big food crisis to hit the region in the last seven years. The 2012 WAM forecast, observed climate conditions and the ongoing socio-economic implications for the region are reviewed here.

Highlights

Living up to its reputation as a highly variable climate system, the West AfricanMonsoon (WAM) in 2012 contrasted strikingly with that of the previous year, when it was delayed, patchy, and irregular
The onset of the WAM coincides locally as the Harmattan winds) crossing the sub-Saharan Africa falling by a devastating with the establishment and development of African continent
As the west African rainy season drew a cold tongue of water in the Gulf of Guinea shift of the monsoon at its ‘onset’ time cor- to its close with a relatively rapid southward in mid-April, resulting from atmospheric responds to a 10–15 day transition in the retreat of the rain belt (Cornforth, 2012: forcing in this area and oceanic processes WAM seasonal evolution, and its mean date Figure 6), the humanitarian impact was sig

Summary

Introduction

Living up to its reputation as a highly variable climate system, the West African. Monsoon (WAM) in 2012 contrasted strikingly with that of the previous year, when it was delayed, patchy, and irregular. The region experienced its third biggest food crisis in the last seven years, this time triggered by severe flooding following on from the drought in 2011, and previously the floods in 2010. Time series (1941–2012) of average normalized April to October rainfall departure (σ) for hydrological events (Figure 1) in western 20 stations in the west African Sudano-Sahelian zone (11°–18°N) west of 10°E. The rain belt moves abruptly north to the Sahel (11°N), as the low-level moist southwesterly flow is diverted inland between the Atlantic cold tongue and the Saharan heat low

Background

Consensus seasonal forecast

Analysis and verification

CENTRAL AFRICA REPUBLIC

Findings

Number of affected people per country