Soldier & Wood River Valley Mtns

Triggering large, destructive avalanches isn't out of the question. You can greatly reduce your risk by avoiding rocky and wind-affected slopes. You could trigger slides remotely—from flat terrain below, above, and to the sides of steep slopes. 

You could trigger an avalanche where yesterday's strong winds may have formed fresh, thin wind slabs near ridgelines in alpine terrain. While these slides should not be large enough to bury people, they could knock you off your feet or carry you where you don't want to go. Additionally, winds may have transported snow into steep terrain on the south half of the compass. Extended periods of sunshine today may produce loose snow avalanches (sluffs) in very steep terrain. Pay attention to the terrain above you, and minimize the time you spend below large cliffs and couloirs. Wind slab avalanches or sluffs could step down and trigger larger, more dangerous, Persistent Slab avalanches.

Triggering 2-5 foot thick persistent slab avalanches is not out of the question. These avalanches can fail larger than expected and be triggered remotely from flat terrain below, above, and to the sides of steep slopes. Over 100 avalanches have been reported since the post-Christmas storm. Recent events—both natural and human-triggered—highlight a pattern: NW, N, NE, E, and SE-facing terrain above 8,500' is the most concerning. Don't rule out triggering a large avalanche on solar slopes, especially where recent winds have built thick drifts. You are more likely to trigger an avalanche in areas where the snowpack is shallow. Shallow snowpacks exist in the eastern and southern mountains, OR in areas where the wind has redistributed snow, creating thinner spots where a skier or rider could more easily trigger an avalanche. Avalanches could be remotely triggered from these thinner areas, resulting in larger, thicker avalanches that could break above you. 

When we look back over the last week, we remain cautious about stepping into steep, consequential terrain:

• On Tuesday, Sun Valley Ski Patrol remotely triggered an avalanche while conducting mitigation work in closed terrain. This slope was artificially loaded by snow making equipment. 
• On Sunday, a group in the Frenchman Ck drainage reported remotely triggering an avalanche (2-3 feet thick, near 9000' on a NW-W aspect) while skiing in safe, gentle terrain nearby. The slide appeared to release in a wind-affected clearing a couple hundred feet below a lightly corniced, treed ridgeline. 
• On Saturday:
  • Jan 4th,  snowmobilers in the Salmon River headwaters remotely-triggered a very large avalanche from several hundred feet below where the avalanche originated. The resulting slide caught, carried, and fully buried one of the riders. The rider deployed his airbag and was carried through trees. The other riders located the buried rider and extricated him from the debris in approximately 15 minutes. He was alert when he was evacuated to a local hospital for evaluation. The avalanche occurred on a NE aspect near 9500’ in elevation, was about 900 feet wide, and averaged 4 feet thick. 
  • Riders in Pole Creek triggered a small slide at a road cut (D1) and observed several other larger avalanches during their ride. They referred to the snowpack as "Very touchy" in shallow areas. 
• On Friday, skiers noted a large avalanche below the Spring-Cherry Ridge that was likely triggered remotely from the nearby skin track. The avalanche occurred on a NW aspect near 9200'. 

Conditions can be tricky as signs of instability like cracking or collapsing and recent avalanches become less obvious. Don't be lulled into a false sense of stability, and approach steeps slopes with a degree of suspicion. If you choose to enter avalanche terrain, you can stack the odds in your favor by avoiding areas with wind-affected snow and terrain peppered with rocks. You can further stack the odds in your favor by avoiding large avalanche paths and those with terrain traps (creeks, trees, or gullies where you would be carried or buried).