What is the critical snowfall rate for the Intermountain climate?

• A. 1 inch/hr
• B. 2 inch/hr
• C. 1.5 inch/hr
• D. 0.5 inch/hr

Answer: (C)

In the Intermountain climate, the important idea is how fast new snow loads the snowpack to create a slab over a weak layer. The critical rate represents the point where loading becomes rapid enough to significantly raise avalanche danger. About 1.5 inches of snowfall per hour is that tipping point here—it’s fast enough to push the snowpack toward instability during a storm, whereas slower rates tend to allow more time for settling and bonding, reducing immediate risk. So 1.5 inch/hr is the best descriptor of the typical critical loading rate for this region. The other options—0.5, 1, and 2 inches per hour—either underestimate or overstate the usual rapid-loading threshold in this climate.