ASDIP ANALYSIS is a software for the generation of loads and the analysis of structural elements. It includes the generation of snow loads on a roof structure, considering the snow drift for several conditions. This a step-by-step example of the generation of snow loads using ASDIP ANALYSIS.
https://www.asdipsoft.com/asdip-analysis/
https://www.asdipsoft.com/snow-loads-example/