Snowpack Analysis & Weather Interpretation Flashcards
7 cards from real ASC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Snowpack Analysis & Weather Interpretation flashcards as text
What weather condition most commonly produces surface hoar?
Answer: Clear, calm nights with high humidity or fog, allowing water vapor to deposit on the snow surface
Surface hoar forms when water vapor sublimates directly onto the cold snow surface under calm, clear, humid conditions — similar to frost on a window.
After a period of warm, sunny weather in spring, when is wet avalanche hazard typically HIGHEST?
Answer: Mid- to late afternoon when solar heating has penetrated the snowpack
Wet avalanche hazard peaks in the afternoon when cumulative solar heating has saturated the snowpack surface and upper layers, reducing snow strength.
What is 'settlement' in snowpack metamorphism and how does it affect stability?
Answer: Compaction and rounding of snow grains under gravity, generally improving layer bonding and stability
Settlement causes snow to compact and grains to round, increasing contact area and bonding between crystals, which generally strengthens the snowpack over time.
Which terrain feature is most likely to be a wind-loaded, high-hazard area?
Answer: A lee slope or terrain feature sheltered just downwind of a ridge
Lee slopes and cross-loaded gullies sheltered just downwind of ridges collect wind-transported snow, creating thick, stiff wind slabs that are prone to avalanche.
What does it mean when a buried weak layer is described as 'reactive but not propagating'?
Answer: The layer fractures easily but the fracture does not spread across the slope
A reactive but non-propagating weak layer can fracture at a specific point but the crack arrests before spreading, meaning a slab cannot release — still a concern if propagation potential changes.
Which observation in a snow pit suggests the snowpack is gaining strength and stabilizing?
Answer: Rounded, well-bonded grains with good layer adhesion and no sudden fracture in stability tests
Rounded grains with strong inter-layer bonding indicate equilibrium metamorphism under warmer, wetter conditions, building snowpack strength and stability.
What is the role of 'aspect' and 'elevation' together in avalanche danger assessment?
Answer: They combine to define specific terrain zones where particular problems exist, such as north aspects above treeline having persistent weak layers
Avalanche bulletins specify danger by both aspect (compass direction) and elevation band because snowpack conditions vary dramatically — e.g., persistent weak layers may exist only on north aspects above treeline.