The majority of Atlantic hurricanes develop from African Easterly waves that grow through a mixed barotropic / baroclinic instability on the African Easterly Jet. The transformation from AEW to tropical cyclone depends on a number of factors, including small vertical shear of the horizontal wind and high humidity in the mid-troposphere. Recently it has been proposed that the proximity of a tropical cyclone to the warm, dry and dusty Saharan Air Layer may inhibit its intensification, although the high relative vorticity associated with the SAL may be beneficial for the initial stages of cyclogenesis. Using LM we have modelled cases in which AEWs developed into tropical cyclones and interacted with the SAL. We have implemented the technique for objective analysis of the AEJ and AEW trough lines of Berry et al. to analyse the results. We carried out a series of 72 h forecasts initialised at 00 and 12 UTC from 12 August – 06 September 2004. During this period there were a number of AEWs, 3 of which developed into the hurricanes Danielle, Frances and Ivan. The horizontal resolution was 0.25° with 35 levels. Initial and boundary conditions were taken from the DWD global analysis.

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