A stochastic model of wind generation in an optimal power flow (OPF) dispatching program is presented. The model includes the error in wind power forecasts using a probability or relative frequency histogram. Compared with the deterministic OPF, the proposed model allows the coordination of wind and thermal power while accounting for (i) the expected penalty cost for not using all available wind power and (ii) the expected cost of calling up power reserves because of wind power shortage. The stochastic model is integrated in an extended conic quadratic OPF program in which wind driven generators are represented as induction machines. Simulation results are presented for cases where the forecasting error histogram is either derived from historical data or estimated by a bimodal normal distribution. The effect of the skewness of the error distribution on the optimal dispatch policy is studied.