ASC Snowpack Analysis & Weather Interpretation 2 — Questions and Answers
Question 1: What does a 'whumpfing' sound while traveling on snow typically indicate?
- A stable, consolidated snowpack settling normally
- Sudden collapse of a weak layer, signaling high avalanche danger (Correct answer)
- Wind slab formation on the surface
- Ice lens cracking due to temperature change
Correct answer: Sudden collapse of a weak layer, signaling high avalanche danger
Whumpfing is the sound of a weak layer collapsing under load, which is a critical red flag indicating the snowpack is primed for avalanche release.
Question 2: Which crystal type forms through temperature gradient metamorphism in a strong temperature gradient (>10°C/m)?
- Rounded grains
- Faceted crystals (Correct answer)
- Melt-freeze crusts
- Surface hoar
Correct answer: Faceted crystals
Strong temperature gradients cause water vapor to migrate upward and recrystallize into faceted, angular grains that bond poorly and create weak layers.
Question 3: A column of fresh snow is placed on a slope and immediately collapses. This most likely indicates:
- Dense, well-bonded snow with good strength
- A reactive weak layer capable of propagating a fracture (Correct answer)
- Normal settlement of new snow
- Presence of a melt-freeze crust
Correct answer: A reactive weak layer capable of propagating a fracture
Sudden collapse during an Extended Column Test (ECT) or similar test indicates a fracture-prone weak layer that can propagate — a significant avalanche concern.
Question 4: Which weather pattern most rapidly destabilizes a snowpack?
- Slow, steady snowfall over 48 hours
- Rapid warming with rain at elevation (Correct answer)
- High pressure with clear skies
- Light northerly winds below 15 mph
Correct answer: Rapid warming with rain at elevation
Rain on snow adds liquid water into the snowpack, rapidly lubricating weak layers and dramatically increasing wet avalanche hazard.
Question 5: What is 'solar radiation loading' in avalanche forecasting?
- Increased snowpack density from wind compaction on sunny aspects
- Warming of south- and west-facing slopes by the sun, weakening surface snow strength (Correct answer)
- UV radiation measuring technique used in field tests
- Snowfall rate increase during clear-sky afternoons
Correct answer: Warming of south- and west-facing slopes by the sun, weakening surface snow strength
Solar radiation heats exposed slope aspects, melting surface bonds and triggering wet or loose avalanches, especially on south- and west-facing slopes in spring.
Question 6: During an Extended Column Test (ECT), what does 'ECTP15' mean?
- No fracture observed after 15 taps
- Fracture propagated across the column on tap 15 in the wrist zone (Correct answer)
- 15 cm of propagation observed in the column
- Column collapsed entirely after 15 shoulder taps
Correct answer: Fracture propagated across the column on tap 15 in the wrist zone
ECTP indicates a propagating fracture (P) during the Extended Column Test, and the number (15) is the tap count when fracture occurred, with wrist-zone taps being a moderate signal.
Question 7: Which factor makes a buried weak layer MORE likely to persist and remain reactive over time?
- Frequent warm rain events wetting the snowpack
- Cold, dry weather with little new snow allowing continued faceting (Correct answer)
- Heavy snowfall loading that rapidly buries it deeply
- High humidity causing rounding of crystals
Correct answer: Cold, dry weather with little new snow allowing continued faceting
Cold, dry conditions maintain the temperature gradient that drives faceting, keeping buried weak layers angular and poorly bonded for weeks or months.
ASC Snowpack Analysis & Weather Interpretation 2
What does a 'whumpfing' sound while traveling on snow typically indicate?