Turnagain Pass

Deep slab avalanches are the primary concern for today.  Large, dense and potentially deadly slabs continue to sit on a weak foundation.  Clear and cold weather for much of October, November and the first half of December created thick layers of weak, faceted snow.  The steady stream of moisture beginning around Christmas formed the deep slab that we are worried most about.

At this point, it is getting more and more difficult to trigger these avalanches.  But make no mistake; getting tangled up in one of these avalanches has the potential to do a lot of damage.  It is common for this type of avalanche problem to lay dormant for extended periods of time.  It has been 4 days since any natural avalanche activity and 3 days since any human or explosively triggered avalanches have been reported.  With clearing skies and good visibility it will be tempting to venture onto steep terrain.  Do not forget what is down below your feet or sled-weak rotten snow capable of producing very large avalanches.  It is unlikely that the normal warning signs of recent avalanches, shooting cracks or collapsing will be present prior to a deep slab avalanche releasing.

Pit tests over the last several days continue to illustrate this problem well.  The weak layer is hard to impact, but the outcome once it is affected translates to large avalanches propagating across wide areas.

Very small shallow (<6″) wind slabs formed yesterday in the higher elevations, where light density snow was easily transported by light to moderate winds.  We witnessed very small shooting cracks in the surface snow above treeline yesterday.  While this problem is relatively minor, it is worth paying attention to today in upper elevation starting zones.