Turnagain Pass

A glorious sunny Saturday coupled with 20″ of new low-density snow two days prior and it was no surprise many folks were out enjoying themselves in the mountains yesterday. With many people on the slopes it is not big surprise many there were 8 reported avalanches at Turnagain Pass and one in the Girdwood Valley. As far as we know, no one was caught in any of these and many were remotely triggered. They ranged in size from very small to just large enough to bury a person and did not propagate very wide. They were all soft slabs 1-2.5′ thick, less than 100′ wide and composed of Thursday’s new snow. Please see the list of observations sent into us HERE as well as highlighted photos below – a huge thanks to all the folks taking the time to send us their photos and reports! 

The new snow is sitting on a layer of buried surface hoar that is inhibiting bonding to the old snow surface. This is creating a new persistent slab avalanche problem for our mountains that could linger for some time. The reason these slabs have not been propagating into larger avalanches is the slab is still very soft and generally non-cohesive. The areas the slab is cohesive is where triggering is possible, such as where winds have loaded/stiffened the snow, where the slab has settled and become cohesive on it’s own and it’s that time of year where the sun can create a slab by warming steep South aspects. Hence, if you are headed out today, and this week, keep these points in mind:

– Are the winds picking up enough to transport snow? This will be a big question moving forward for slab development!
– Quick hand pits are great ways to assess changes in the new snow character
– Watch for cracking and whumpfing – this was prevalent yesterday
– These avalanches may seem small now, but could start to propagate wider with passing time and/or fresh wind loading 

*Remember your safe travel protocol – expose one person at time, watch your partners, have escape routes planned

 
Fourth skier on slope triggered this slab avalanche on Max’s Mountain  pictured below, SW face at 3,000′. 

Two skier remote triggerd slabs on the upper SW face of Eddies Ridge  (Photo: Joe Engel)

 Snowmachine triggered wind slabs in Main Bowl (1st Bowl) of Seattle Ck drainage near the Widowmaker slide path (Photo: Bryan Pfaender)

Skier triggered slab with a ski cut on Tincan Proper, 1-2.5′ thick and 30′ wide (Photo: Meg Smith)

Small wind slab human triggered in Hippy Bowl on Tincan Ridge, westerly facing rollover (Photo: Heather Thamm)

–

Loose snow avalanches ‘sluffing’ is possible on steep terrain features protected from wind. Small slabs may entrain loose snow below and could run faster and farther than expected. 

Triggering a deep slab is becoming difficult, but is still possible above 3000′ where a hard slab is sitting on a variety of weak layers in the mid pack and near the ground. The most likely trigger spots are in thin areas in the snow cover, often near rocks, or where the slope rolls over. The Southern end of Turnagain Pass to Johnson Pass is more suspect due to a thinner snowpack. Remember, this is a ‘low probability, high consequence’ situation. 

*** There is very little info in the Johnson Pass and Lynx Creek zone. If you’re headed to either of these areas and you observe any signs of instability: recent avalanches, shooting cracks, or whumpfing please send us an observations HERE.