Turnagain Pass

The storm ended yesterday, and left a blanket of fresh snow across all elevations and aspects of the mountains.  This is good news for backcountry quality, but makes it difficult to identify the areas of greatest concern.  Wind during the storm was trending from the east, so westerly aspects may be harboring wind pockets and larger cornices. 

A big piece of information came in yesterday from Seward highway/AKRR crews when they triggered a large avalanche near Kern creek.  The avalanche below was larger than anything we’ve seen in quite some time.  This begs the question – Is it still possible for a person to trigger a larger avalanche today?  It seems unlikely, but perhaps not impossible.  We think that areas closer to Girdwood may be somewhat less stable than Turnagain Pass.  This is due to greater snowfall in the recent storm cycles, and a more prominent crust/weak layer combination that has shown it can cause big avalanches.

Other storm related issues to think about –

1.  Wind loading up high – few people have ventured above 2500 feet in the last week due to poor visibility and stormy weather.  Watch for wind slabs in steep terrain.  This is a wild card, for which we currently don’t have a lot of information.

2.  Cornices – are likely to be large and unstable.  We found very small cornices to be easily triggered on Thursday.

3.  Loose sluffs – Steep terrain may have enough loose powder to entrain and pick up volume.

In Turnagain Pass, we have seen occasional pits that indicate avalanche propagation is possible on a melt/freeze crust that typically varies from 1-3 feet in depth.  This problem is not evident everywhere…  The most reactive elevation seems to be between ~1900 and ~2900 feet.  It has shown itself to be worse in Girdwood than Turnagain Pass.

The video in this link illustrates the nature of the crust problem.  It isn’t easy to initiate, but when it does it may propagate into deeper layers.