Preparing forecasters to respond in extreme weather situations is a difficult task due to their limited occurrence. However, simulations offer a way to involve forecasters in practicing decision-making for even the most complex situations. This chapter describes the evolution of tools and processes for using simulators in forecaster training and assessment within an international collaborative community. The results have led to tools that anyone can easily use to create weather forecasting simulations, as well as many different applications for their use. Results and feedback have shown that simulations greatly enhance the practical side of courses and allow increased work on developing skills