Rossby wave trains and their waveguides: dynamics, predictability and forecast errors (RW-GUIDE)

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High-amplitude Rossby wave trains can trigger severe weather events in the North-Atlantic European region. The extended lifetime of such precursor wave trains may be exploited to improve the forecast of severe weather events. Our knowledge of the predictability and forecast errors associated with Rossby wave trains and their waveguides, however, is limited. We propose to first diagnose the physical and dynamical processes that govern the propagation of synopic-scale Rossby wave trains and the formation and maintenance of their waveguides. More specifically, barotropic, baroclinic, and diabatic contributions will be quantified. We will use the ERA-interim and Year Of Tropical Convection data sets. A large number of cases shall be considered focusing on high impact weather events. Two complementary methods based on inversion of potential vorticity and on trajectory analysis will be used. We will then determine objectively the predictability of the wave trains from ensemble data, and the forecast error structure of waveguides from the deterministic ECMWF forecast. These analyses will be combined to link predictability and forecast error characteristics to the physical processes that govern the evolution of the Rossby wave – waveguide couplet.