Northwest Mountains

You can trigger a slab avalanche in the recent storm snow several feet deep.  The most concerning slopes are well-drifted from strong winds during the storm.  Weaker snow exists beneath the recent snow on many slopes which may maintain the threat of triggered avalanches even in sheltered terrain. Carefully assess recent wind-loading patterns to avoid the most drifted slopes and investigate the bonding between the recent storm snow and old surfaces before committing to terrain steeper than 35 degrees.  Warming temperatures today may produce natural loose avalanches from features that are steep, sunny, and rocky.

Northwest Mountains:  A few changes were made to products today.  The first is a transition from the Storm Slab problem due to snowfall from 1/27 through 1/30 to a Persistent Slab problem.  The lingering threat of triggered avalanches due to lightly faceted snow grains, and crusts on some features, beneath the recent storm snow, required a change in the problem name.  A good example can be found in this observation of a skier-triggered slide on a  roller below Red Lady Bowl on Mount Emmons.  The small roller was described as "fairly loaded up" and "my track was the 5th or 6th track on the feature before it went".  Carefully read wind-drifting patterns and avoid terrain that appears to be loaded.  Upper snowpack problems may last through this weekend.

The second change in the Northwest Mountains forecast was the removal of the Deep Persistent Slab problem.  It has been several weeks since the last natural deep failing avalanche and a week since explosive control work at Irwin produced an avalanche on basal weak layers.  The chance for you to trigger an avalanche on deep layers is not zero, but very unlikely.  Consider this outside chance if you choose to travel in abnormally shallow or highly variable depth terrain with many trigger points like cliffs, rocks, or vegetation.

Southeast Mountains:  The Storm Slab problem has been removed and issues with the recent storm snow have been placed with the Persistent Slab problem.  The greatest concern with the recent storm snow resides in terrain drifted by the wind and less concern in sheltered areas where slabs are softer and thinner.  Much like in the Northwest Mountains, carefully assess loading patterns and be cautious of well-drifted features.

Forecast products continue to reference the threat of avalanches failing at the bottom of the snowpack in areas with below-average depths.  Depths in the range of 90 to 130 (3 to 4 feet) are the most concerning as weak layers are well within the reach of the weight of a person.  Yesterday, an observation near Taylor Reservoir (outside the CBAC forecast area but similar snowpack depth to areas near Mount CB, Whetstone, lower Brush Creek, and lower Cement Creek) reported a skier-triggered avalanche that broke near the ground in basal facets.  The snowpack was around 4 feet deep; the ideal depth for triggering a dangerous avalanche on basal weak layers.  We are not out of the woods yet for deep breaking avalanches in the Southeast Mountains, particularly in portions of the zone with shallower snowpack depths.  If you think the snowpack is capable of failing near the ground, then choose slopes with angles around 30 degrees that are not connected to steeper terrain.

Your observations are especially helpful as skies clear and we assess how the multiple weak layers in our snowpack responded to the most recent storm.  You can submit observations here, or by texting photos to 970-444-2170.