A case study of an intense convective event occurring in the Swiss Alps (Davos) is presented. Polarimetric X-band observations of this event showed an unusual strong signature in terms of differential reflectivity Zdr, differential phase shift on backscattering δ , and correlation coefficient ρ hv. The nature of the event is investigated as well as the possible microphysical processes that may lead to high values of δ and Zdr at X-band. In addition, the consistency between the polarimetric radar variables is experimentally studied.