Northwest Mountains

The streak of triggered persistent slabs continues.  Yesterday, several unintentional and explosive triggered persistent slabs were reported on the heels of two large remotely triggered slides on Thursday.  The snowpack is tricky and dangerous right now.  Conservative mindset and terrain selection are essential today.  Carefully manage for the threat of triggering a persistent slab, even from below the slope remotely.  Rumbling collapses and shooting cracks are signs of danger warning you to choose lower slope angles.

A few of my favorite quotes from recent observations:

• “Nearly pant altering”  after a sizeable collapse in Washington Gulch yesterday.  
• "Things out there are being described as touchy; unpredictable and scary..." CBMR, after continued explosive persistent slab results yesterday in closed terrain. Thank your local ski patrollers for their hard work mitigating avalanche risks. Respect their terrain closures.  
• "I like to think I've experienced a wide range of conditions in a continental snowpack but today expanded that continuum. Truly wild."  Eric, after remotely triggering a large avalanche from a collapse that ran hundreds of feet through mature aspens.  

Scroll through our observations page and read our weekly summary for highlights from a large natural cycle on Monday night. This aerial observation has lots of avalanche eye candy.  You don't have to be an expert to realize that our snowpack is challenging and dangerous: collapses, shooting cracks, and triggered slides fill the calendar since December 10th, the date that our horrid weak layer was first buried.  As our snowpack distances itself from Monday night's storm, the danger will continue to very slowly trend down.  The trend comes from an increasing number of exceptions to the general rule that anything steep will avalanche.  Finding those exceptions requires thoughtful terrain and snowpack assessments.  The sunniest aspects (south, southwest, and lower elevation southeast) are generally lacking persistent slab structures on steep terrain and recent storm instabilities have largely healed.  Paths that have shed their persistent slab structure from previous avalanche activity are safer.  In the shallowest parts of the Southeast Mountains, the slabs are still very thin and faceting away now.   And in the deepest snowpack of the Northwest Mountains, weak layers are starting to gain strength and slabs are becoming more stubborn to trigger.  Although the likelihood of triggering a persistent slab is decreasing in the Northwest Mountains, we are still urging conservative travel advice given the unusual behavior, large size, and some forecaster uncertainty.   Riding low angle terrain is always the most reliable choice for handling uncertainty. Circling back to quotes that started this discussion: when conditions are tricky, expect surprises.  Prepare for those surprises by giving yourself a wide margin for error and practicing tight travel protocols.  That means carrying all the rescue gear, keeping close visuals on your partners, spacing out for even small clearings or terrain features, and choosing routes that minimize your exposure to remote triggering.  Make that your New Year's resolution for the rest of this winter.  

Winds are increasing today ahead of a weak disturbance.  If you see winds transporting snow, expect thin wind slabs to be forming near ridgelines and beware of the threat of a few naturals from wind drifted slopes.