The feasibility of a dynamical model for forecasting the development and dissipation of fog and stratus is studied. Several simple models based on numerical solutions of the diffusion equation are developed and tested. The resulting predictions are examined with regard to the likelihood of achieving any degree of success with this type of model. The observational data required for the predictions, and the time and space scales on which the observations must be made are noted. Abstract The feasibility of a dynamical model for forecasting the development and dissipation of fog and stratus is studied. Several simple models based on numerical solutions of the diffusion equation are developed and tested. The resulting predictions are examined with regard to the likelihood of achieving any degree of success with this type of model. The observational data required for the predictions, and the time and space scales on which the observations must be made are noted.