Snow avalanches is considered among the most dangerous natural disasters that cause material damage but also dozens of deaths every year. The concerned countries have allocated important resources to manage this disaster. Space-time avalanche observation and prediction can help save people's lives and minimize damages. In this context, this article provides a comprehensive insight on existing avalanche forecasting systems. We review observed natural phenomenons and parameters that most existing systems use, then we discuss existing methodologies for snowpack modeling. We establish a comparative study on most important methodologies and tools for avalanche prediction. Finally, we give some recommendations and discussion for building an operational prediction system.