Forest fires are of common occurrence all over the world, causing the loss of precious natural resources. The propagation of forest fires depends on many factors, notably local weather conditions. Additionally, the local terrain such as mountainous areas also plays an important role. For instance, forest fires may propagate from mountain ridges to ridges due to locally strong wind by means of firebrands and hot air flows. While much is known cm the methodologies on the forest fire control, they are largely empirical and may not be totally effective. Therefore, scientific studies based on fundamental physical understanding of the underlying phenomena are needed to provide definitive data on cause-effect relationships in various forest fire scenarios, so that the collective database can be used to suggest control strategies and preventive measures for forest fires. The present study is motivated by this approach, and specifically focuses on the phenomena of rapid forest-fire propagation from mountain slqpes to other similar mountain slopes in the direction of the wind. The study deals with both laboratory experiments and numerical simulations by the use of a CFD-based fire field model.