Northern Wallowas

Wind-drifted snow 1-3 feet thick has created unstable snow.  This further overloads weak layers from January, creating a problem that is difficult to manage on all aspects and elevations.  You could trigger an avalanche large enough to bury, injure or kill you.  Avoiding slopes greater than 30 degrees is your best travel tool, but if you choose to enter avalanche terrain, relentlessly think about the consequences of your route choices.  

This forecast is sponsored by SUP, Kayak & Tube Rentals - The Trailhead (thetrailheadbakercity.com) 

A persistent slab needs two ingredients: a weak or soft layer below (the facets we've been finding and discussing for weeks) and a stronger or harder layer above (the new snow this week).   As the name suggests, the persisting layer will stick around and be slow to strengthen.  The slab above it gained a major load on Tuesday night, tipping the scales and triggering natural avalanches on some slopes.  Although we've had minimal precipitation since then, an inch here and there adds up, as does wind amplifying the slab's load.  Slopes that didn't avalanche already are closer to the breaking point.  

• On shady and wind-sheltered northerly aspects, February's snow will not bond well to the 10-12" of weak, sugary facets and/or surface hoar. 
• On solar aspects, a buried melt-freeze crust may provide a slick bed surface and certainly harbors weak sugary snow below it.  We have had one confirmation from the S Wallowas of a persistent slab triggering below the 1/31 melt-freeze crust.  

What to do:   A persistent slab avalanche needs two more ingredients: a slope greater than 30 degrees to initiate, and a natural or human trigger.  With uncertainty about which slopes have the right combination of slab ingredients to be unstable enough, you can hedge your bets by choosing low-angle terrain or, at the least, inconsequential pieces of avalanche terrain. 

As always, be on the lookout for the freebie signs of unstable snow: recent natural avalanches, shooting cracks, and whumphing of the snowpack.   With a persistent slab problem, the absence of these clues does not mean that a slope is safe to ride, and careful evaluation should be used moving forward.   If you're not in avalanche terrain, you can't get caught in an avalanche.  

Observations:   Northern Wallowas and Southern Wallowas reports from yesterday, Feb 5, highlight surface wind effect and concerning test results down 1.5' on a mid-storm layer and 2.5' down on the 1/31 crust, including one column so weak that it failed on isolation.  Caleb in the Wing Ridge zone was able to intentionally trigger small windslabs and observe numerous previous avalanches.  A ski guide nearby also found similar propagating tests on the same two layers at NW 7100'.  

A ski guide in the southern Wallowas reported many natural slab and loose avalanches releasing on Tuesday night's cycle Near Treeline on E and W aspects, with large slides (D2's) triggering below the 1/31 melt-freeze crust and depositing up to 4.5' of debris on the road.

 Here are Southern/Western Wallowas reports on 2/4 from a current and a former forecaster.   There have been no observed persistent slab avalanches in the Burger Butte/Taylor Green area yet, with two nearby suspect northerly mid elevation slopes producing wind slabs instead.  

Add value to your avalanche forecast.  Help us reduce uncertainty.   If you get out today, please submit an observation sharing where you traveled and if you saw avalanches or signs of instability.  How deep your boots sink into the snow is an easy gauge for how much snow the wind might transport.