House of cards under foot

Today we rode the machines into the northern Swan Range.

• As was the case in the valley, it was raining at the trailhead when we left in the morning.  The rain turned to snow at roughly 5000'
• Our first pit was on the road at the snow line and we found a reactive slab 20 cm thick that was failing below the 1/13 crust in small facets.
• With increased snow and wind we opted to assess some test slopes before going into any bigger terrain.  The first steps off the machines near the convexity of a ridge and we heard the collapse, saw shooting cracks and watched as a remotely triggered avalanche munched its way through a snag patch for a few hundred feet below us.  Further investigation reveled 2-3 mm buried surface hoar above the 1/13 crust as the culprit.  Stage now set for the day.  
• We dialed back terrain selection and spent the rest of the day hunting for this layer on different aspects and elevations.  We found the buried surface hoar on all aspects and up to 6500' (we did not go any higher than this today).  It was consistently failing with easy force in all of our test pits, down approx 20 cm.  
• The 1/13 crust abounds but did not seem to be as touchy as the surface hoar layer.  In most cases the surface hoar was above the crust a few cm.  
• We remotely triggered 3 separate avalanches throughout the day, all of them on protected N/NW slopes.  All of these were triggered from well back on the ridge lines and after making sure there were no people below.  Depths ranged from 6'' to 16'' with crowns of 100-200' wide and wrapping around ridges.
• It was snowing all day with periods of up to 1 inch/hour.  Total accumulation was probably 3-4 inches in the higher elevations.

The greatest observation of the day was made well before we started the sleds, however.  Our plans as of last night had been a ride into larger terrain.  Based upon the weather we saw this morning and our conversations at the trail head we opted for a ride that allowed us to make decisions along the way that would keep us off of bigger slopes and out from under larger terrain.  A goal oriented day in conditions such as these may have turned out differently for us.