[MCR] Powder Creek Southern Purcells

March 1^st -8^th Powder Creek lodge

Lila Orr and I guided the past week at Powder Creek lodge in the Southern Purcells across from Kaslo.  Overall we had excellent conditions and recent warmth did not affect the snow until March 7. The week saw 90cm of snow falling with gradually warming temps and settled to 55cm. Travel was challenging due to deep trail breaking for the past 2 days but the powder was deep and plentiful.  We were able to ski steep trees to 40 degrees but only very limited alpine terrain.  The week started with -25 deg temps at TL and ended with slightly above 0 deg temps.  We had light to moderate west and south-west winds all week that created windslab on lee aspects at treeline and above and built cornices.  The weather and poor visibility limited us to skiing mostly at treeline and below. We dug profiles on North and South aspects at tree line and found the Feb 10-Jan 28^th layer to be 100-140cm down.  This layer was un-reactive to compression tests, but still reacting suddenly to deep tap tests.  This lead us to avoid slopes with shallow areas where we thought this layer could be reactive and avoid exposure to overhead hazard during times of snowfall and warming.   Our suspicions were confirmed on March 5^th when we were traveling on a ridge with shallow snow and we remotely triggered a size 2.5 avalanche below us from 20m away.  The slide initiated in on a steep adjacent lee (SE) aspect that had significant loading from the winds.  The crown was 150m wide, ran 150m long and was 160cm thick at its deepest point and 20cm deep at its shallowest.  This was a good reminder that this layer is still a concern in the right place.  Although visibility was limited we saw evidence of a natural avalanche cycle out of steep lee and cross loaded features, and as the skies cleared we were able to see the crown but not all of a suspected sz 3 on a steep south alpine face at 2450m, we presently suspect the Jan 28/Feb 10 layer to be the culprit but can not confirm.  We also had one natural cornice failure on a steep SE face that triggered sz 2.5 slab just beside the crown of the remote avalanche.  The warmth that occurred  March 7^th created 5cm of moist snow on all aspects to 2100m.  The recent storm snow is well settled and bonding to the Feb 28^th interface.  Have fun and stay safe.

 

Judson Wright ACMG ASG

Lila Orr ACMG SG

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