Snow stratigraphy information is among other sources the key data for assessing avalanche danger-not only for dry snow but also for wet-snow conditions. Until now this information is obtained by traditional snow pit observations or more recently by applying more quantitative methods such as the snow micro-penetrometer or dielectric devices. All these methods are destructive and only provide a snap shot in time of snowpack evolution. We used an upward-looking ground-penetrating radar system (upGPR) to monitor snowpack evolution on a daily or, whenever necessary, hourly basis to obtain information on wet-snow properties. We focused on determining the volumetric liquid water content (θ w) by calculating the effective permittivity (ε eff) of the wet snow above the radar antennas, the advance of a wetting front and the wet-snow stratigraphy. ε eff was obtained using the signal velocity and snow depth recorded with nearby ultrasonic gauges; θ w was calculated with different mixing model approaches. Results were compared to in-situ measured permittivity, modelled wetting front advance and modelled and measured outflow at the bottom of the snowpack. The upGPR system clearly showed the advance of a wetting front and the arrival time was similar to the one recorded with a nearby lysimeter. Possibly weak wet layers with high liquid water content (θ w>6%) were detected within the radar signal by multiple reflections. However, determining the exact amount of liquid water for each layer separately is still a task for future research. © 2011 Elsevier B.V.