The term *a priori* refers to the amount of information available in a system. Based on the amount of a priori information, mathematical modeling problems are often classified into white-box (a system in which all necessary information is available) or black-box (a system in which there is no a priori information available) models. Practically all systems are somewhere between the white-box and black-box models; thus, this concept only works as an intuitive guide on how to approach a mathematical problem.

Many different types of data, including air pressure, temperature, humidity, and so on, must be taken into account when constructing computer models of hurricanes.