1. ALPTRUTH Avalanches in the area in the last 48 hours Loading by snow, wind or rain in the last 48 hours Paths, Avalanche paths Terrain Traps Rating, considerable or higher on the current avalanche bulletin Unstable snow: Collapsing or cracking Thaw instability, recent warming of the snow surface 92% of all accidents happen when 3 or more of these things are present.

2. A A valanches Signs of recent slides –Natural slides within the last 48 hrs –Teton Pass is closed –Debris on the roads –In www.jhsnowobs.org or on the BT reportwww.jhsnowobs.org ALPTRUTH

3. Photo Peter Thurston

5. Photo Evan Howe

6. L oading Snow or rain in the last 48 hours An inch an hour for 6 or more hours, making 8” total or more Amplified by terrain features Amplified by high winds ALPTRUTH

7. Loading: amplified by wind From The Avalanche Handbook, McClung and Schaerer

8. T. Leonard Photo LoadingwindwardLeeward SafeScary!

9. P aths : Avalanche Paths Large and small Recognizable by a novice Funnels and fans What are the clues? ALPTRUTH

10. Path anatomy

12. Trim line, flag trees

14. Terrain Traps Often near creekbeds, roadcuts Often not as obvoius Consequences of being caught are amplified “nowhere to run” ALPTRUTH

15. Terrain Traps : Is there an escape route?

16. Photo Don Sharaf

17. Photo Brad Sawtell

18. Rating: what does the avalanche report say? www.jhavalanche.org 307-733-2664 Caution if it is Considerable, High, or Extreme ALPTRUTH

19. Rating ALPTRUTH

20. Unstable Snow Collapsing or Whumphing Shooting cracks Heavy over weak ALPTRUTH

21. Shooting Cracks

22. Photo Don Sharaf

23. What sound does this make when weighted?

24. Th Th aw Instability Rapid temperature rise: The FIRST time the temp rises 12-15 degrees F in 12 hours or less after a long cold spell ALPTRUTH

25. Effects of Temperature on a Slab Cold temps = frozen and hard slab  Rapid warming and skier triggering  General warm temps and settlement  Wet snow and the Melt-freeze regime

26. Thaw Instability: rapid warming

27. AVALANCHE TRIANGLE WEATHER TERRAIN SNOWPACK

28. Red Light Factors Weather: –Recent strong winds –Recent heavy snow or rain –Sudden warming ( +12 to 15F over 12 hrs)

29. Red Light Factors Snowpack: –Shooting cracks, “whumphing”, recent avalanches –“heavy over weak” layering, especially with a persistent weak layer under a heavy well- bonded slab –Low scores or Q1 shears in tests

30. Red Light Factors Terrain: –Slopes steeper than 30, or in the runout of those slopes –Avalanche paths marked by scarred, missing, or sparse trees –Terrain traps such as gullies, cliffs, trees, crevasses, lakes –Recently wind loaded slopes –Localized areas of convexity, especially with thin snowpack and rocks underneath

31. Red Yellow Green Light Red Yellow Green Light Decision Making Red Light Terrain -30-45 degrees -Leeward -Loaded Snowpack -Natural Avalanches -Collapsing -Shooting Cracks -Heavy over Light -Easy test scores -Q1 Shears Weather -1” an hour for 6 + hours -<12” in 24-48 hours -Wind -Rapid Warming Don’t forget the Human Factor - Risk Tolerance -Experience -Group Size -Powder -Male

32. ALPTRUTH Avalanches in the area in the last 48 hours Loading by snow, wind or rain in the last 48 hours Paths, Avalanche paths Terrain Traps Rating, considerable or higher on the current avalanche bulletin Unstable snow: Collapsing or cracking Thaw instability, recent warming of the snow surface 92% of all accidents happen when 3 or more of these things are present.