Turnagain Pass

Another warm, wet and windy storm is impacting the Eastern Turnagain Arm region once again. This system moved in yesterday afternoon and will be exiting today. So far we have seen just under an inch of rain up to 2,500′ with heavy wet snow above this. The rain has likely melted most surface crusts up to 2,500′, and possibly higher, and will continue to saturate the snowpack. This will create wet loose avalanche potential along with an increased glide avalanche potential.

Since the pack has already adjusted to rain up to 2,500′ from the last storm, it is not prime to produce significant natural wet avalanche activity. Yet, at the upper elevaitons we may see some shallow wet loose avalanches in the new snow as temperature climb slightly today. That said, human triggered wet loose snow avalanche will be possible on steep slopes where loose, unconsolidated and soggy snow exists. On sustained steep slopes these could be quite large. Avoiding steep terrain with unsupportable wet snow is recommended. 

Glide Avalanches:
We are currently in a “glide cycle” of sorts. We have seen widespread glide crack development through Turnagain Pass and Girdwood Valley during the past 3 days. Only a handful of these cracks have actually avalanched. Check out the comparison photo below put together by Heather Thamm. This shows that not all glide avalanches are preceded by a slowly opening crack. Something to keep in mind if you are headed out in the backcountry. This can make avoiding being under a glide avalanche more tricky, but most of the time they do have glide cracks present which are easy to recognize.

While it has been raining up to 2,500′, it has been snowing above this. I think it is safe to say that around 5-8″ of heavy to medium density snow exists and covers essentially the top 500-1,000′ or so of the ridgelines around Turnagain Pass. The new snow has come in with strong Easterly winds which has likely built wind slabs up to 8-16″ in depth. Another 2-4″ of snow is expected with moderate Easterly winds today which, if this is the case, add to the slabs from the past 24-hours. These will be sitting on a hard pre-existing crust and bonding of the new slabs to the older crust is uncertain. However, I’d expect with the warm temperatures, that these slabs should settle out rather quickly and be somewhat stubborn to trigger. 

If you are headed out in search of new snow at the high elevations, watching for red flags (recent avalanches, collapsing and cracking in the new snow) will be essential. Quick hand pits are an additional great way to see how the new snow is bonding.