Pockets of wind slab may linger on various aspects in exposed terrain and around ridgelines.
There is some evidence that the persistent avalanche problem may still be rider triggered especially in north facing terrain at treeline.
Watch for lingering pockets of wind slab on various aspects in exposed terrain and around ridgelines. Northeast winds from earlier in the week reverse loaded features building slabs in less common places.
These slabs have formed on top of old crusts and hard wind-pressed snow and there is uncertainty about how quickly they will bond to old surfaces.
Surface hoar layers buried in January have been implicated in two recent size 2 avalanches in the region. Various combinations of crusts above and below these layers have made the distribution and sensitivity of this problem difficult to pin down.
Be cautious on northerly steep open slopes around treeline where these layers are most likely to have been preserved and linger.
THURSDAY: Clear, light westerly winds and alpine low of -16.
FRIDAY: Partly cloudy, light westerly wind, and high of -8.
SATURDAY: Mostly sunny, moderate southwest winds, alpine high of -4.
SUNDAY: Cloudy, moderate southerly winds, alpine high of -4.
This week there have been several skier-controlled and accidentally triggered wind slabs near ridge crests, mostly in the size 1-1.5 range. Surface hoar layers buried in January have also been implicated in two recent size 2 avalanches in the region.
Recent northeast winds have scoured and wind-affected open areas forming wind slabs in lee terrain. This reverse loading means there may be wind slabs lingering in unusual places. In sheltered locations, there is likely around 20-40 cm of snow over an old February drought layer interface that consists of various melt-freeze crusts and old wind-pressed snow depending on your elevation and aspect.
Two layers of buried surface hoar sit in the upper snowpack and are likely most reactive in sheltered areas at treeline. These are now down around 40-70 cm deep. Though improving, these layers remain reactive in some snowpack tests and have been responsible for sporadic avalanches, including a size 2 that was triggered remotely by a skier walking on a ridge on Monday.
The lower snowpack is well consolidated, with a crust/facet layer found 100 to 200 cm deep. It is currently considered dormant, but could become active later this season. Check out the forecaster blog for more information.
