Turnagain Pass

A slow and steady spring time shed cycle persists. This is where above freezing temperatures cause the snowpack to loose its strength and becomes wet and saturated releasing naturally or with the weight of a person/snowmachine. The last two nights we’ve seen temperatures dip below freezing again in the upper elevations – causing a crust to form. Unfortunately this re-freeze is superficial and clouds have kept some heat in and mid elevations temps are still above freezing. Today and tomorrow it will be important to monitor this crust and pay attention to how much the sun and/or rain showers break it down. This is the time of year when avalanches from above can catch you by surprise. Solar aspects in the afternoon and evening are most vulnerable. Be aware that steep rocky areas with thin snow coverage heat up fast and natural activity will be more likely in these areas – including slopes that have already seen lots of avalanche activity. For Friday: If skies remain cloudy overnight and temperatures remain above freezing in the alpine a surface crust on Northern aspects may start to melt, making wet avalanches possible on all aspects.  

WET SLAB, WET LOOSE and CORNICE FALLS:
Things to keep in mind if you are headed out: 

1. Is the snowpack frozen or wet and soggy? A hard frozen snowpack is stable, a soft mushy snowpack is dangerous.
2. Are you punching through a shallow crust into wet soggy snow? A shallow re-freeze is still weak and could avalanche.
3. Are you seeing recent avalanches?
4. Are you in a runout zone? Can an avalanche releasing above wash debris over your location? Avalanches can run into valley bottoms.
5. Buried weak layers in the pack can make a small avalanche or sluff larger by propagating across the slope and/or stepping down.
6. Wet avalanches are hard to escape if you get caught. A small slide can be deadly if it pushes you into a terrain trap.

Similar to the wet issues above, glide avalanches are also occurring with the springtime melt-down. Glide cracks are opening up and releasing on many slopes in the region – steer clear of any slopes harboring glide cracks. Check out the photo below from the motorized up-track. This slope is notorious for producing glide avalanches. Additional glide avalanche activity is expected today and through the week.

There are several buried persistent weak layers in the snowpack; ranging from buried surface hoar 2-6′ deep, mid-pack facets and facets near the ground. Shallow snowpack zones such as the Summit Lake area harbor depth hoar near the ground. On upper elevation North, West and Easterly aspects these weak layers could re-activate if the surface crust starts to melt and become wet on these aspects. If this melting occurrs triggering a larger natural slab avalanche may be possible.