Egger, J. (Meteorologisches Institut Universitat Munchen)
Theories of lee cyclogenesis are reviewed and grouped according to their main thrust. In a first group one is looking into the interaction of fronts with orography. It is easier to produce lee cyclones if one considers the motion of broader baroclinic zones over orography. Problems with this approach are discussed as are those linked to theories of upper-level flow features passing over the Alps. It is pointed out that most theories capture some part of the observed developments. It is argued that a satisfactory is not available at the moment. The principal difficulties are discussed that such a theory must face.
Numerical experimemntation provides a possibility to partly overcome this impasse. Corresponding examples are presented.