Turnagain Pass

Over the past several days, the region has experienced winds capable of transporting loose snow.  As a result, wind slabs have formed in many exposed areas of the Alpine and Treeline elevations.  Due to varying wind directions and localized geography, some areas have experienced this wind effect more than others.  Because of this it’s especially important to pay close attention to indicators of wind slab formation where you are and where you’d like to go.  These clues of wind effected snow could include: firm surface conditions, cracking, hollow or drum like sound/feel, and visual cues of recent wind activity such as pillowing and scouring.  If you find these indicators, it’s prudent to reassess the plan.

Observers from Summit Lake to Crow Pass have found hard wind effected snow along ridgelines and through valleys that channel the wind. Small natural and human triggered wind slabs have been observed and the avalanche that occurred Friday evening on the Crow Pass trail was a large hard slab avalanche involving wind effected snow.

Wind transported snow observed at Mt Adair south of the advisory area.  1.13.2020  Photo: Alex McLain

Persistent is defined as: “continuing to exist or endure over a prolonged period.”  Related and synonymous words include: dogged, insistent, patient, persevering, tenacious, assured, certain, dedicated, determined, firm, hell-bent, intent.

Whether you like it or not, persistent layers including buried surface hoar and facet layers exist within the snowpack.  These weak layers have been found 1-3′ deep and have a slab formed on top of them. It remains possible for a human to trigger a large slab avalanche.  With that said, the trend of this concern is moving toward unlikely. The confusing part is these weak layers cannot be found everywhere throughout the advisory area.  The only way to know if they exist where you’re located is to dig and test.  If this type of investigation is not within your skill-set, it’s probably sound to assume they exist.  As always, good travel practices are called for: minimizing exposure and traveling one at a time, or choosing routes with lower angles, and outside of the run out of an avalanche path.

In this non-windloaded test pit at Tincan, observers found good stability and no concerning weak layers.  1.13.2020.  Photo: CNFAIC Archive

Loose snow sluffs:  On slopes out of the wind the surface snow is becoming looser and looser by the day with the cold temperatures. Sluffs are getting larger because of this and gaining volume on longer sustained slopes. Expect sluffing in steep terrain with loose snow.  Remain mindful when traveling over cliffs and rocky outcrops.

Cornices:  Give cornices plenty of space and limit your exposure when passing beneath them.

Glide avalanches: Glide cracks continue to open but there have been no recent reports of glide avalanches. Due to their unpredictable potential to release, the travel advice remains the same: limit your exposure while traveling under glide cracks.