ASC Avalanche Forecasting & Danger Ratings 1 — Questions and Answers
Question 1: How many danger levels are on the North American Public Avalanche Danger Scale?
- 3
- 4
- 5 (Correct answer)
- 6
Correct answer: 5
The North American Public Avalanche Danger Scale has 5 levels: Low, Moderate, Considerable, High, and Extreme.
Question 2: Which avalanche danger level is associated with the highest number of avalanche fatalities historically?
- High (4)
- Extreme (5)
- Considerable (3) (Correct answer)
- Moderate (2)
Correct answer: Considerable (3)
Considerable (Level 3) is associated with the most avalanche fatalities because it is the level at which human-triggered avalanches become likely and many travelers underestimate the risk.
Question 3: On the North American Avalanche Danger Scale, at which danger level are 'natural and human-triggered avalanches certain'?
- High (4)
- Extreme (5) (Correct answer)
- Considerable (3)
- High (4) and Extreme (5) equally
Correct answer: Extreme (5)
At Extreme (Level 5), natural and human-triggered avalanches are certain, and large to very large avalanches will occur.
Question 4: What does the term 'avalanche problem' refer to in a forecast?
- A specific avalanche that has already released
- The type of snow instability likely to produce avalanches (Correct answer)
- A hazard caused by road closures
- An error in the snowpack model
Correct answer: The type of snow instability likely to produce avalanches
An avalanche problem describes the type of snow instability present — such as Wind Slab, Storm Slab, or Persistent Weak Layer — that is most likely to produce avalanches.
Question 5: Which organization is primarily responsible for issuing public avalanche forecasts in the United States?
- FEMA
- The National Avalanche Center (NAC) and regional avalanche centers (Correct answer)
- NOAA exclusively
- The US Forest Service Avalanche Division
Correct answer: The National Avalanche Center (NAC) and regional avalanche centers
The National Avalanche Center (NAC) coordinates a network of regional avalanche centers that issue public forecasts across the US.
Question 6: What is the primary purpose of including 'likelihood' in an avalanche forecast?
- To describe how large an avalanche will be
- To indicate the probability that avalanches will be triggered (Correct answer)
- To predict how far debris will travel
- To specify which slopes have already slid
Correct answer: To indicate the probability that avalanches will be triggered
Likelihood in a forecast communicates the probability that a person will trigger or encounter an avalanche, ranging from unlikely to certain.
Question 7: What does 'size' in an avalanche problem assessment refer to?
- The vertical drop of the starting zone
- The destructive potential of the avalanche relative to a person or structure (Correct answer)
- The width of the fracture line
- The total area of the runout zone
Correct answer: The destructive potential of the avalanche relative to a person or structure
Size in avalanche forecasting refers to the destructive potential of the avalanche — from D1 (relatively harmless) to D5 (could destroy a large building or forest).
ASC Avalanche Forecasting & Danger Ratings 1
How many danger levels are on the North American Public Avalanche Danger Scale?