Most work in natural language processing is geared towards written, standardized language varieties. In this paper, we present a morphology generator that is able to handle continuous linguistic variation, as it is encountered in the dialect landscape of German-speaking Switzerland. The generator derives inflected dialect forms from Standard German input. Besides generation of inflectional affixes, this system also deals with the phonetic adaptation of cognate stems and with lexical substitution of non-cognate stems. Most of its rules are parametrized by probability maps extracted from a dialectological atlas, thereby providing a large dialectal coverage.