Turnagain Pass Avalanche Forecast

The storm on Monday dropped 12-15 inches of snow in some parts of Anchorage.  You can expect to find similar amounts in the Turnagain forecast region, with Girdwood getting a little more in the areas we’ve surveyed.  A notable feature of this storm was the cold temperatures.  The snow fell cold and dry, making for a light density powder with low water content.  Despite only moderate wind during the storm, the light powder was easily moved around by wind.  There are a lot of wind affected slopes, varying from scoured surfaces on one aspect, to stiff wind slab, to sheltered pockets of loose powder.  

Today, the wind slab is my greatest concern.  Yesterday we found a couple pockets of stiff supportable wind slab that collapsed with a “whoomph” when we skied across (see pit profile and description here).  Given a steep enough slope, this would probably initiate a small avalanche.  Furthermore, the problem can be even worse if it sits on top of a sun crust.  The two things I would actively try to avoid today – stiff wind slab on steep slopes, and southerly aspects where reactive sun crusts may be found.  

If you can avoid these two issues, there are still pockets of good quality loose powder to be found.

The recent stretch of sunny weather produced 2 specific weak layer concerns.  

1.  Sun crusts on south aspects.  We found at least 3 distinct buried sun crusts yesterday, with the top one being moderately weak with a tendency to propagate.  A number of smaller skier triggered avalanches have been reported in the last week, and the majority seem to be on southerly slopes, probably because of the sun crust layers.

2.  Non sun affected slopes simply got weaker in the surface snow during the 2 weeks of clear weather.  Weak snow by itself isn’t necessarily a problem, until you get stronger or stiffer snow on top of the weak snow.