This paper presents a stochastic model for analyzing the effects of variable precipitation on the Nordic power system. The model is formulated as a multistage stochastic linear program and solved by the ReSa sampling based Benders decomposition method. The stochastic parameter representing the inflow to the hydro reservoirs has been split into two in the model to describe separately the inflow from rain and snowmelt. This captures the fact that information about the snow reservoirs reduces the decision maker's level of uncertainty about future inflow levels. Computational analysis of the Nordic power market undertaken using the model confirms the importance of modeling multiple inflow sources, with the addition of the snow reservoirs reducing the span between the highest and lowest expected future spot price.