What is the critical snowfall rate for the Maritime climate?

• A. 1 inch/hr
• B. 1.5 inch/hr
• C. 3 inch/hr
• D. 2 inch/hr

Answer: (D)

The important idea here is how fast new snow loads the existing snowpack. In Maritime climates, storms bring moist, heavy snow that adds weight quickly. When the snowfall rate reaches about 2 inches per hour or more, the added load comes on fast enough that the upper layers can form dense slabs on weaker layers beneath, and there isn’t enough time for the snow to settle and bond gradually. This rapid loading increases the potential for slab avalanches to release under less disturbance, especially when wind and temperature conditions help create cohesive slabs.

If the rate stays below roughly 2 inches per hour, the snowpack has more time to respond, settle, and bond, which can reduce immediate instability compared to a fast-loading storm. That’s why 2 inches per hour is used as the benchmark for a higher risk in Maritime climates.