In order to assess whether a fog or stratus event is possible, you must evaluate the synoptic-scale influences that will drive the local conditions. In this module, we examine several common synoptic situations to understand the processes involved in fog or low stratus development. Most of these are forced primarily by advective or dynamic processes (although radiation does play a role). A more detailed discussion of radiation processes is contained in the Radiation Fog module. This module is part of the Distance Learning Course 1: Forecasting Fog and Low Stratus.