ACMG Mountain Conditions Summary for the Rockies and Columbia Mountains issued June 15th, 2017
It has been rainy and mostly fairly calm the past couple of days in both ranges. Freezing levels have been observed as high as 3350m(11,000 ft) and light snow has been reported as low as 2300m along the Rockies Divide and in the Bugaboos yesterday. All the rain and warm air will help settle the snowpack somewhat in the long term but it was a deep moist "slushie"of a snowpack up to at least around 2700m yesterday at Lake O'Hara. My guess would be that conditions are similar at that elevation throughout the ranges. The exception would be some of the big avalanche deposits from late winter as that snow is still very dense.
Without large triggers like solar radiation, lots of rain or cornice/serac falls it seems that natural avalanches are unlikely. In the O'Hara slush yesterday human triggered avalanches only seemed likely if you were pushing the snow around by bum sliding or skiing and triggering moist point release avalanches. These could definitely dig deep in the moist snow and be big enough to bury someone, push your over a cliff or pile you into the rocks.
We still don't really have a lot of observations from high North facing terrain except from some ski tracks and the odd climbing party, so there is still uncertainty about whether the Alpine snowpack could still produce large slab avalanches. Time will tell but I would still be somewhat conservative in the alpine in variable snowdepth areas or on warm days.
The snowline is definitely rising and sunny alpine rock routes will be coming into shape if the weather clears as forecasted for the weekend. Castle Mountain still has some big snow patches but it could probably be managed. South facing routes in the Bugaboos and Rogers Pass have been climbed. Snow conditions could be excellent IF there is a good freeze. Coming into the shortest nights of the years so it will take a clear night and cool temps up high to get a real freeze. if you are venturing into big steep snow routes like Lefroy or Sir Sandford it would be worth sticking an avalanche probe into the snow to see if it really frozen full depth or just formed a crust that will leave you hip deep in slush when it melts. Finding yourself hip deep in snow on a big face could be a really lonely kinda feeling.
Larry Stanier
ACMG Mountain Guide