The layered structure of a snow pack has a great effect on several important physical processes, such as water movement, reflection of solar radiation or avalanche release. With the present study we aim at investigating what factors are most important with respect to the formation and persistence of distinct layers in a sub-alpine environment. We used a physically based numerical 1-dimensional model to simulate the development of a snow pack on a sub-alpine meadow in central Switzerland during one winter season (1998/99). A thorough model validation was based on extensive measurement data including meteorological and snow physical parameters. The model simulated the snow water equivalent and the depth of the snow pack as well as the energy balance with high accuracy. But the observed strong layering of the snow pack was not reproduced satisfactorily. In a sensitivity analysis, we tested different model options and parameter settings significant for the formation of snow layers. Neglecting effects of snow microstructure on the compaction rate and the current description of the water redistribution inside the snow pack, that disregard capillary barrier effects, preferential flow, and lateral water flow, were the major limitations for a more realistic simulation of the snow pack layering.