23rd National Avalanche School

Snowbird Ski and Summer Resort, UT October 27-31,2013

Student Prework

MOUNTAIN SNOWPACK PRE-WORK (Ethan Greene) NOTE: For an introduction to the material to be covered read the course materials (USB drive.) Excellent additional information can be found in Chapter 5 of Staying Alive in Avalanche Terrain, 2nd edition (Tremper, 2008) and Chapter 3 of the Avalanche Handbook, 3rd edition (McClung and Schaerer, 2006). 1. Why does snow change form (metamorphose) so easily and quickly under the conditions

we commonly find in the mountain snowpack? 2. Why is the development of a layered structure in the snow cover important for avalanche

formation? What is the role of snow metamorphism in the development of these layers? 3. Different layers within the snowpack may be a result of the different storms that

deposited those layers. Once on the ground, snow can further differentiate through metamorphism. Name the three main types of snow metamorphism, provide a brief description of processes involved, and describe the resulting snow crystals.

4. What is the average temperature gradient within a snow cover which is 50 cm thick when

the ground temperature is 0 degrees C and the temperature at the snow surface is -10 degrees C? Is this temperature gradient sufficient for faceted crystal growth?

5. In the above example, if the density throughout the snowpack is similar, where in the

snowpack would you expect to find the fastest growing faceted crystals? Why? 6. In dry snow without a strong temperature gradient, what would you expect to happen to

the strength of the snowpack? Describe the snow crystals you might expect to see. 7. In a typical mid-winter snowpack, where might you expect to find the strongest

temperature gradients? What are some of the mechanisms driving those high temperature gradients?

8. Melt-freeze metamorphism can create ___________ layers in the snow (stronger, weaker,

or both?). Explain. 9. What tends to happen to the grain size after repeated cycles of melt-freeze

metamorphism? Why? 10. Define settlement, glide, and creep.

SNOW PROFILES AND TESTS PRE-WORK (Doug Chabot) Note: Read Chapter 2 and Appendix F in Snow, Weather and Avalanches: Observational Guidelines for Avalanche Programs in the US. Use these pages as a reference as you look at the snow profile. Study the snow profile form on the next page and answer the questions. Snow Pit Profile setting: This pit was dug to the ground 40 feet away from the top of an open and obvious avalanche path. The path’s dimensions are 200 feet wide at the top, 800 feet long and 500 feet vertical. 1. What is the weakest layer in the snow profile?

2. What crystal types does this weak layer consist of? 3. Looking at the snow profile, what weather may be responsible for this layering? 115-70 cm: 70-45 cm: 45-44 cm: 44-43 cm: 43-40 cm: 40-39 cm: 39-0 cm: 4. With time, if conditions stay similar, would you expect the facets at the ground to grow into bigger facets or begin to round?

2013 NAS PRE-WORK: READINGS AND ONLINE STUDIES FOR TERRAIN ANALYSIS

Chris McCollister

A lot has been written on Avalanche Terrain by people much more articulate than me. I think Bruce Tremper captures the topic best in his book, which is required reading for the course. Please take time to read the Terrain Management chapter it since you’ll get more out of my lecture if you do. I’ve also included a link to an online avalanche course with emphasis on the Avalanche Terrain module. Required Reading: Bruce Tremper’s book, Staying Alive in Avalanche Terrain (2nd edition), has a thorough and well written section on Terrain Management. Read Chapter 3, pages 67-96 to familiarize yourself. We will cover all this material in the lecture. Required Online Studies: The Canadian Avalanche Association has a fantastic online avalanche tutorial. I recommend grabbing a cup of coffee and taking the entire thing. But for the purposes of this lecture, go to: http://www.avalanche.ca/cac/training/online-course Then click on “Reducing risk in the field”. This will launch the avalanche terrain portion of the course. Additional Readings: The Avalanche Handbook, by David McClung and Peter Schaerer, pages 89-102. Snow Sense, by Jill Fredston and Doug Fesler, pages 14-25. Or, just go ahead and read the whole book, it’s only 100 pages!

2013 NAS PREWORK QUESTIONS Chris McCollister

Terrain Analysis

QUESTIONS: 1. What is the most important terrain variable when trying to determine if a slope is capable of producing an avalanche? Why? 2. What other terrain factors affect the ability of a slope to produce avalanches? 3. What is the relationship between slope angle and stress?

4. If you are traveling across an unstable snowpack that is only 12 degrees steep, is it possible to trigger a slide and get caught? Explain.

Avalanche Formation and Release – Prework Karl Birkeland

For your prework for this topic, read these articles (located under the Avalanche Formation and Release section of your course material/USB drive) and come to the school with your questions! • The effect of changing slope angle of extended column test results: Can we dig pits in safer locations? by

Karl Birkeland, Ron Simenhois, and Joachim Heierli The data in this paper help to show the importance of collapse in fracture propagation. In addition, the results have important practical implications for stability evaluation.

• On the sustainability and arrest of weak layer fracture in whumpfs and avalanches, by Dave Gauthier and Bruce Jamieson

Don’t let the title of this paper intimidate you. This is a clearly written paper on weak layer fracture and arrest, two important components of avalanche release.

• The effect of changing slab thickness on fracture propagation, by Ron Simenhois and Karl Birkeland This paper looks at the effect of changing slab thickness of fracture propagation. The results are

relevant for both avalanche mitigation work with explosives and skier triggered avalanches. • Review of spatial variability of snowpack properties and its importance for avalanche formation, by Juerg

Schweizer, Kalle Kronholm, Bruce Jamieson, and Karl Birkeland This paper provides a thorough, though fairly academic, review of the spatial variability research prior to 2008 and the implication of this work for avalanche release. Don’t worry about the details in this article since we will discuss the important points at the school.

• Post-control avalanches, by Liam Fitzgerald Liam wrote this paper for the National Avalanche School, but it remains relevant today. He presents two possible scenarios for post-control releases. We will discuss in lecture why Scenario I is much more likely than Scenario II.

I also recommend that you pick up the 2011 edition of Snow Sense by Fredston and Fesler and read pages 55 through 63 for a straightforward and simplified description of avalanche release. If you want to check out more articles on avalanche release, as well as many other topics related to snow and avalanches, here are two good places to get a start on some of the newer articles that are available: • Forest Service National Avalanche Center –

http://www.fsavalanche.org/NAC/techPages/techPap.html (recent NAC papers, theses, etc.) • University of Calgary Applied Snow and Avalanche Research Group – http://www.eng.ucalgary.ca/Civil/Avalanche/papers.htm (recent papers by U of C’s ASARC)

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MOUNTAIN METEOROLOGY – PREWORK Knox Williams 1. List several weather elements that contribute to avalanche formation and the instrument(s) used to measure

each. Element Instrument Importance to avalanche formation

(1)

(2) (3) (4) (5)

2. What are the four important atmospheric lifting mechanisms? Which is the most important for producing

mountain snowfall? 3. (a) How does the relative humidity change when temperature changes? Why?

(b) What does this have to do with condensation?

(c) What does this have to do with the formation of surface hoar?

4. What are the two processes by which ice crystals grow inside a cloud? 5. List several ways that mountains affect radiation, temperatures, winds, and snowfall. 6. You are in charge of the avalanche program in your area. You take data at 0600 and see that 12 inches of new snow have fallen since your last measurement at 2000 the night before, and that snow contains 1.00 inch of water equivalent. Ridgetop winds have averaged 25 mph and gusted to 50 from the southwest.

(a) Compute the average snowfall intensity.

(b) Compute the precipitation intensity.

(c) Compute the new snow density.

(d) Which slopes do you suspect are heavily loaded with new snow?

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Extra Credit: 7. It is raining hard in Seattle (sea level) and the temperature is 41 degrees F. (5 C). Calculate the

temperature at Stevens Pass east of Seattle (4,000 feet or 1,220 meters.) Is it raining or snowing there? 8. A strong west wind is blowing in Denver (5,300 feet or 1,616 meters) and the temperature is 50 degrees F

(10 C). What is the temperature at Berthoud Pass due west of Denver (11,300 feet or 3,446 meters)?

SNOW STABILITY EVALUATION- (2013) Pre-work: read student notes section & complete this before lecture 1. As you are climbing a snow slope, you can hardly kick toeholds with your boots. What does this say about the stability of the slope? What other factors would you like to know about? 2. Eight inches of low density snow has recently fallen in the area of your camp, which is located on the south side of an east-west oriented ridge. The avalanche danger is presently moderate. What factor(s) would increase the instability and make the avalanche danger increase to high within a matter of hours, or sooner? Why? 3. List four snow layers, which contribute to instability on avalanche slopes. 4. Many clues concerning snow instability are there, if you look for them. What is the best clue? 5. In terms of evaluating avalanche hazard, how does slope angle relate to instability? 6. What various factors, or conditions, will cause snow to strengthen? Why?

7. Is layer hardness an important factor to look at in the snowpack? If so, why? If not, why not?

8. List all the weather factors you can think of which would tend to increase the instability of the snowpack and say why.

9. As you travel across a snow slope, you hear a "whumphing" noise beneath your feet. What is happening and why? 10. You are approaching a snow-covered slope from the top with the intention of descending. What factors do you consider important in judging its stability?

Safe Winter Travel Prework – (Bruce Tremper)

1. Name four parameters you use to judge the danger of avalanche terrain.

2. Name four essential safe travel protocols you should always practice in avalanche terrain. 3. Having the right equipment is an important part of safe travel techniques. Besides a beacon, shovel and

probe, name three other important pieces of equipment or equipment considerations that can help keep you alive.

4. Describe how to manage the terrain with various levels of snow instability. In other words, what kinds of terrain can you cross or cross beneath in red light, yellow light and green light situations.

Avalanche Protection Fundamentals Prework (Paul Baugher) 1. You and your control team partner are traveling one at a time in an avalanche path. The

visibility conditions are poor. You are about to lose sight of your partner. How will you manage this situation?

2. You are responsible for the avalanche protection of a section of new highway. The starting

zones are very difficult to access.

(a) Give two examples of engineered protection that could be used. (b) List two methods for artificial release that could be used.

3. Snow removal maintenance crews are opening a road that has been closed all winter.

(a) Give an example of risk to the crew. (b) How would you manage that risk?

4. Your control team has thrown hand charges in the 3 previous paths with no results other than

craters. You are now preparing to control a north-facing slope. The top of this path appears much more wind scoured than the previous paths. Unfortunately, poor visibility restricts your view to the very top of the path only.

Weather for the past 24 hrs: Old Surface Hard Crust New Snow 6” Wind SW 40-60 mph Temp range 5° - 10° F Discuss the following: (a) Explosives placement and method of delivery (b) Do you expect to see an avalanche?

(c) If so, what type?

(d) What are some possible effects of the wind

(e) What is the effect of visibility

(f) What is your interpretation of your control results so far?

5. Give examples of control techniques for wet snow: 6. You are at the top of a starting zone about to make your first ski cut of the new season. List three mistakes you could make.

Avalanche Rescue Fundamentals Prework (Craig Sterbenz)

Additional Reading: Located under the Rescue Fundamentals section of your course materials (USB drive) are articles and other additional reading materials relating to this topic. Although they are not “required” reading, these documents have been included to bring you the most recent information or innovation on the subject and I would suggest your familiarize yourself with them. Incident Command System (ICS) Training; FEMA Online Course Rationale and Models for Transition of Management of Avalanche Rescues from the Three Stage Model to the Inci-

dent Command System by Drew Davis and Dale Atkins Incident Command System (ICS) - Glossary Avalanche Rescue Paradigm Shift: From Individual Tools to an Integrated System by Dale Atkins Telluride Ski & Golf Resort - Avalanche Rescue Plan Time to Change Rescue Attitudes for a New Generation by Dale Atkins Sidecountry Rescue: Who is Responsible? By Don Shockey, Chip Morrill, and David Immeker Improving K-9 Avalanche Team Performance and Communication in Backcountry Avalanche Missions: A Collabora-

tive Approach Between Ski Patrol and K-9 Search and Rescue (SAR) Teams by Susan Purvis and Patti Burnett Avalanche Survival Strategies for Different Parts of a Flowing Avalanche by Karl Birkeland, Theo Meiners, and Perry

Bartelt How Effective are Avalanche Airbags? Field Tests of Avalanche Safety Equipment by Lorenz Meier and Stephan

Harvery Strategic Shoveling: The Next Frontier in Companion Rescue by Bruce Edgerly and Dale Atkins V-Shaped Conveyor-Belt Approach to Snow Transport by Manuel Genswein and Ragnhild Eide Avalanche Rescue Dogs by Dean Cardinale Resuscitation of the Avalanche Victim: An Evidence-Based Guideline by Jeff Boyd, Hermann Brugger, Fidel Elsensohn, Peter Paal, Giacomo Strapazzon, Eveline Winterberger, Ken Zafren

In 2011, the National Ski Patrol published the second edition of “Avalanche Rescue Funda-mentals,” written by Dale Atkins and Lin Ballard. This notebook is “required” reading for any serious student of Avalanche Rescue. If you are a NSP member, please go to http://www.nsp.org and log into the NSP store to purchase a copy for your library. Copies will also be available for purchase from the registration desk at The School.