The missing teleconnection between the North Atlantic and the Sahel precipitation in CFSv2

This study presents new findings on the link between interannual variabilities of atmospheric circulations over the North Atlantic and precipitation over the African Sahel (P-S). Our analysis shows a meridionally stratified circulation wave train resembling the East Atlantic (EA) mode, apparently connected to P-S through Rossby wave dispersion in the middle troposphere originating from the North Atlantic. However, the Climate Forecast System version 2 fails to depict the EA and its P-S impact. Because the EA explains 29% of variance of P-S, this portion of P-S variability is either missing in the seasonal forecast, or being made up by an alternative process.