Turnagain Pass

During a 60-hour period, ending last night, sustained ridge top Easterly winds averaged in the mid 40’s mph with gusts as high as 88mph. We estimate snow totals to be around 12-16” in upper elevations, but unfortunately it is impossible to calculate since much of this snow has been blown away. Yesterday visibility was poor and conditions were too dangerous to access the alpine thus we don’t have much information about how the snow was loading on large steep terrain. We suspect wind slabs could be as thick as 4-5’ on leeward terrain features and below ridge tops. It is uncertain how easily a wind slab could be triggered in the Alpine today.

At mid elevations (2000 – 2800’) we did find wind slab pockets up to 2’ deep alongside large scoured slopes. We did observe these pockets to be loading low on features and well below scoured ridges. 

The storm’s predominant wind direction was from the East, but due to variable terrain features and very high mid-slope winds all aspects are suspect of wind slabs. You will most likely find isolated pockets at mid elevations and larger pockets on leeward aspects at higher elevations. Safe travel can be found on wind scoured slopes and ridges – which will be obvious, based on their rough texture and signs of old eroded ski tracks.

If you venture into the Alpine stay on scoured ridges and avoid steep terrain with hard, smooth, pillow-like features. Listen for hollow sounds and look for shooting cracks, but realize that wind slabs have a tendency to break once you are well onto the slab. It is best to avoid steep slopes that could be wind loaded until the snow has a chance to stabilize. 

Luckily, this is the type of snow condition that heals quickly as long as temperatures are cool and we don’t see any additional precipitation and wind loading. Cooler temps could also help improve the quality of the riding. Yesterday was quite variable above 2000’. 

We have been tracking a buried surface hoar layer since Dec.18^th when a skier triggered a large avalanche on Sunburst.  There has also been some recent concern of weak faceted snow in thinner areas of our snowpack in Girdwood and Summit Lake. As of the last 48 hours, we do not know of any recent natural avalanche activity occurring on old buried weak layers. There is just enough concern that a human could tip the balance or if a wind slab could step down to keep persistent slabs in the forefront of our minds. We suspect a slab if triggered at this layer could be as deep as 4-6’ in some upper elevation locations. It is best to avoid steep slopes today and let buried weak layers adjust to its new load.