A nonlinear differential equation for the description of the mean annual behavior of snow depth at a point is reconstructed from measured time series of temperature, snow fall, and snow cover, using the so-called Trajectory Method proposed by Eisenhammer et al. [1991>. The temperature and snow fall are used as independent variables of a polynomial equation with nonlinearities up to the third degree. The reconstructed model not only reproduces the original data very well, but also captures the main behavior of the system when forced by different climatic conditions. ¿ 2001 American Geophysical Union