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AVALANCHE AWARENESS. for Snowmobilers. climbers. 138. bc skiers. 130. lift skiers (ob). 58. lift skiers (ia). 24. snowboarders. 27. snowmobilers. 95. misc. recreation. 57. U.S. Avalanche Fatalities by Activity 1950/51 to 2000/01. climbers. 29. bc skiers. 31. lift skiers (ob).
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AVALANCHE AWARENESS for Snowmobilers
climbers 138 bc skiers 130 lift skiers (ob) 58 lift skiers (ia) 24 snowboarders 27 snowmobilers 95 misc. recreation 57 U.S. Avalanche Fatalities by Activity1950/51 to 2000/01
climbers 29 bc skiers 31 lift skiers (ob) 14 lift skiers (ia) 1 snowboarders 22 snowmobilers 73 misc. recreation 23 U.S. Avalanche Fatalities by Activity1993/94 to 2000/01
TYPE OF RESCUE (US) 1950/51-1998/99
With avalanches you have three choices… • Avoid avalanche terrain • Learn about avalanches, minimize your risks • Roll the dice (or pull the lever!)…
SLAB AVALANCHE Starting zone Track Runout zone
Slab Avalanche: • Crown face • Bed surface • Flanks • Stauchwall
KEY FACTORS • Terrain • Weather • Snowpack • “Human Factors”
TERRAIN Is the terrain capable of producing an avalanche?
RECOGNIZING AVALANCHE TERRAIN Factors to consider: • Slope angle • Slope size and consequences • Slope shape • Vegetation/trees • Runout • Aspect w/respect to wind • Elevation
60 deg Slope Angles 45 deg 30 deg 15 deg 0 deg
Slope Shape convexity concavity
Vegetation damage is a sure-fire indicator of avalanche terrain!
38° 36° 40° Trigger Point Burial Point
500 FOOT FRACTURE TRIGGER POINT 800 FOOT RUNNING DISTANCE BURIAL
CROWN FACE PROFILE DEPTH IN INCHES 43 32 6 4 0 NEW SNOW WIND SLAB NEAR-SURFACE FACETS CRUST RELATIVE HARDNESS
WEATHER Is the weather affecting the snow stability? • Snow and Rain • Wind • Temperature