ALPTRUTH Avalanches in the area in the last

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.

Avalanches ALPTRUTH 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 report

Photo Peter Thurston

Photo Peter Thurston

Photo Evan Howe

Loading ALPTRUTH 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

Loading: amplified by wind From The Avalanche Handbook, Mc. Clung and Schaerer

Loading windward Safe Leeward Scary! T. Leonard Photo

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

Path anatomy

Trim line, flag trees

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

Terrain Traps: Is there an escape route?

Photo Don Sharaf

Photo Brad Sawtell

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

Rating ALPTRUTH

ALPTRUTH Unstable Snow Collapsing or Whumphing Shooting cracks Heavy over weak

Photo Don Sharaf

What sound does this make when weighted?

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

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

Thaw Instability: rapid warming

OW SN N AI RR TE PA CK AVALANCHE TRIANGLE WEATHER

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 -Q 1 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

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.