The Colorado Avalanche Information Center has some very useful resources to consult before going out on the slopes this season.
From their website, https://avalanche.org/avalanche-encylopedia/#avalanche-problem, the danger levels range from 1-5. Danger level 2, D2, can bury a person. D3 can destroy a house. D4 and D5 are historic avalanches that can destroy part or all of a village.
If you hear someone say it is a D5, pay attention.