Turnagain Pass Avalanche Forecast

A quick tour to treeline on Tincan yesterday found significant avalanche carnage from the much publicized weekend storm.  Unfortunate for surface conditions, we found a breakable crust entombing 2 feet of settled storm snow up to 2,000 feet.  This crust appeared on the tail end of the storm as temperatures dropped Sunday night, and is acting to promote more stable snow in the mid-elevations (at treeline).  In the alpine however, soft, surface snow is abundant and will be ripe for transport today with winds forecasted in the 20 to 45 mph range.  Fresh wind slabs are likely to form on south and west aspects and may be 1-3 feet deep.  If travelling in the alpine, pay attention to changing surface conditions and drum-like or hollow sounding snow as this is indicative that you’ve found a wind slab. 

With limited visibility yesterday and no observations from the alpine since before the quick-hitting weekend storm, confidence is low that the storm snow is settling without incident.  Careful snowpack evaluation will be essential today if moving through the upper elevations to ensure you are managing terrain appropriately.

Storm slab/ wind slab just lookers left of Tincan proper looks to have avalanched at the tail end of the weekend storm.

Again, visibility hampered a good look into alpine start zones yesterday but given the state of cornices (large and mature) before this storm, you can bet that 4+ inches of water weight from the weekend and winds averaging in the 30’s mph have brought these backcountry bombs ever closer to their tipping point.  Avoid time spent below cornices and keep a healthy distance (and then some) away from the edge if travelling along a corniced ridge today.  Cornices now are as large as we’ve seen all season and have a tendency to break much further back than one might anticipate.  Given the sheer size and weight of any cornice failure today, it’s quite possible a cornice fall will initiate a slab on the slope below.  

I spotted one new glide crack that appeared to have released mid-storm and maybe a hundred others that ‘disappeared’ during the storm.  Unfortunately glides are going to be difficult to see right now due to last weekends fresh snow, but make no mistake, these cracks are still scattered about in the backcountry, mainly in the 1500 – 2500’ elevation band in popular ski/ snowmachine terrain such as Seattle ridge, Main bowl, Tincan and others.  Glide cracks are growing larger by the day but still prove very difficult to forecast for.  Your best bet continues to be to map out where these cracks exist and limit you exposure time below. 

Pre-storm and post-storm photo of Seattle ridge from the motorized parking lot.  Notice the glide cracks in the upper image have all been buried with the subsequent storm.  Make no mistake, glide cracks do still exist and threaten a lot of well-travelled terrain on both the motorized and non-motorized side of the highway.