Turnagain Pass Avalanche Forecast

The Northerly winds that were forecast to hit the area yesterday only bumped up slightly along most ridgelines. Stations reported averages from the North and West in the 10-15mph before settling down last night. This is good news for limited wind slab development. However, areas like Portage Valley, Seattle Ridge and Crow Pass are suspect to have seen stronger winds and subsequent new wind slabs. We had a report of two small slab avalanches (believed to be new yesterday and likely wind slabs) that released on Maynard Mountain in Portage Valley.

With plenty of loose surface snow to blow around, be on the lookout for wind slabs. Textured surface snow, rounded and pillow-like surfaces and feeling for stiffer snow over softer snow are all signs the winds have visited. Cracking in the snow around you will be a sure sign you have found a wind slab. Any fresh slabs are expected to be shallow, a foot or less thick, and could be touchy. These are most concerning if they knock you somewhere you don’t want to go, like over cliffs.

Unfortunately, the snowpack structure above 3000′ is poor. Specifically, there is a hard slab (3-8 feet thick) sitting on a variety of weak layers in the mid pack (including buried surface hoar) and old November facets near the ground. Deep persistent slab avalanches remain a concern on these upper elevation slopes. Triggering a deep slab is becoming difficult, but is still possible. The most likely trigger spots are thin areas in the snow cover, often near rocks, or where the slope rolls over. South of Turnagain Pass the snow cover is thinner, triggering a slab in this area could be more likely as well. Remember, this is a ‘low probability, high consequence’ situation and no Red Flags are likely to been seen (such as whumpfing and cracking). Remote triggering is possible and there may already be tracks on the slope. This issue can simply be avoided by sticking to terrain below 3000’ (which is a good portion of terrain at Turnagain) or choosing low-consequence terrain in the Alpine.

Snowpack structure at 3,600′ on North facing Tincan Ridge below. We found the poor structure in our pit, meaning the weak layers are there, but they were either hard to get to fail or did not want to propagate. This is a good sign, but as long as these weak layers are present, the chance a person can trigger a deadly deep slab remains despite snow pit results…

Watch your sluff. Cold temperatures are ramping up the ‘faceting process‘ in the top foot of the snowpack and sluffs are getting bigger and faster day after day. *Once we do get a new load of snow on this very weak snow, you can imagine just how hard that new snow will be to stick (today’s good riding is tomorrow’s avalanche producer…).

These skier/boarder initiated sluffs on Tincan Proper ran to valley floor in some cases with small powder clouds.

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