Our biggest concern for the Northern Wallowas is the persistent deep slab instability that is showing itself as poor structure in snowpit tests. The most obvious evidence of the deep persistent slab instability is the observance of large natural and skier triggered avalanches in the Big Sheep Basin and McCully Basin areas. These avalanches that fail on persistent grain types buried deeply in the snowpack are hard to trigger but when one is triggered the consequences can be severe.
Wind slabs that formed by recent southerly winds are now buried by the new snow deposited Tuesday into Wednesday. You now may be unable to see these wind slabs but expect them to be present, especially on leeward facing terrain at and near ridgelines.
The Northern Wallowas have a deep persistent slab problem at this time. Large and potentially dangerous avalanches have recently been observed in McCully Basin and Big Sheep Basin. Recent new snow accompanied by copious amounts of wind equals windslabs. These windslabs have added a lot of weight to an already weak snowpack. The extra weight added to the snow by a recreationalist can be just enough to trigger a large and destructive deep slab avalanche. At this time, the best way to manage this situation is to stay off of and out from underneath terrain steeper than 30 degrees. Check out the recent information that has been posted in the Observations section of this website. There you will find good information about the avalanche that occurred in McCully Basin. Also read Victor McNeil's take on this situation. Victor's write up can be found on our Observations page as well.
Dry loose avalanches were plentiful and easy to trigger in the Elkhorns yesterday on steep terrain. I would expect to see these same sluffs occurring throughout the Northern Wallowas as well. On large slopes loose snow avalanches can entrain enough snow to carry a recreationalist into a terrain trap or even bury a person in a gully. Be aware of this when recreating on slopes steeper than 35 degrees today.
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