Aspect: Most likely on SW-S-SE-E-NE

Elevation: Most likely Above Treeline and Near Treeline

The Bottom Line: Extreme arctic outflow has blasted the slopes for the last 6 days. Wind loading has slowed down now that there is less snow available for wind transport. But…recently wind loaded areas are still harboring layers of slab that are possible to be triggered by a human. Avoid stiff wind slab in specific areas prone to slide, such as be wind loaded rollovers, chutes, and gullies steeper than 30 degrees. 

Another note: Some very large cornices have formed on SW, S,  and SE aspects. As always, be sure to give cornices the proper respect: stay WAY back. When they fail, they always break further back than you would expect.

Travel Advice: Watch for red flags (shooting cracks, collapsing or recent natural avalanche activity). Stay away from slopes below top loaded ridgelines, roll-overs, or cross loaded gullies and other features steep enough to slide >30 degrees. Look for stiff, hallow, dense, drum-like slabs. Avoid terrain traps where snow could pile up quickly, or the consequences of a slide could cause injury or death.

Note: Surface avalanches could step down to weaker buried layers, see Persistent Slab problem.

Aspect: Mainly on wind-protected and wind loaded slopes, most likely beneath terrain features on S, SE, and E aspects

Elevation: All elevations, mainly at and above treeline.

Bottom Line: Small surface wind slabs could step down to deeper slabs that have wide propagation.  Identify and avoid features of concern, such as trigger points, sheltered slopes, thin areas in the snowpack and steep wind loaded slopes below terrain features.

Travel advice: Consider any possible slopes harboring buried surface hoar, or other weak snow as guilty until proven innocent. Always use safe travel techniques such as only exposing one person at a time both on the way up and down. Identify and avoid thin areas where weak layers are more likely to trigger a slide from. Group up in safe zones that are out of harms way. Have good communication, including radios and a set plan in case of an emergency. Be practiced at companion rescue..

The persistent slab danger is not going away, it is standing by waiting for the right trigger. We have not had a crush and flush cycle, or stabilizing event.

• Surface hoar from Dec 18th may have been preserved in wind-protected areas. It is now buried by about a foot of snow.
• Recent observations from Old Faithful found a thin crust with weak snow down 60-70cm near 3,200′ and below
• This bathtub ring effect, from lower-elevations to mid-elevation, where freezing levels are more likely to cause crusts and weak layers – should be carefully evaluated.
• Weaker snow (buried facets) forming between wind slabs in the top of the pack

It is still possible that any surface avalanches could step down to deeper weak layers, the October rain crust, or even the ground in alpine areas. 

Buried surface hoar layer (thin grey line) in an opening below treeline in the Transitional zone. This layer is now about 12″ deep. It exists in isolated wind protected areas.