Water flow through a melting snow pack modifies its structure and stability and affects the release of water and nutrients into soils and surface waters. Field and laboratory observations indicate a large spatial variability on various scales of the liquid water content and flow, a dominant system feature currently not included in numerical models. We investigated experimentally water and dye tracer movement through micro-structurally different snow pack horizons and the persistence of preferential flow paths. Naturally rounded snow of varying grain size was sieved into rectangular bins and surface melt was induced with infrared lamps. The flow paths were visualized with tracers and liquid water content was monitored with time domain reflectometry probes. Vertical cuts through the snow pack were imaged. The dye tracer patterns allowed to distinguish the two flow regimes "matrix flow" and "preferential flow". Matrix flow is apparently resulting from film and/or capillary flow in the unsaturated snow matrix. It occurs already at low liquid water contents. The capillary barrier effect at a boundary between a fine over a coarse textured layer on matrix flow in snow was confirmed. In contrast, preferential flow appears as well-defined flow fingers that advance from 0.1 to 1 cm s-1. During a melt phase, the advancing flow fingers enlarge and are only partially time invariant. It remains to be shown whether the continuum concept, including the Darcy-Buckingham law is apt to describe the extremely non-linear nature of water flow and the travel time of solutes in snow under conditions of melt water percolation.