Turnagain Pass

We got limited information from the field yesterday and did not hear of any human triggered avalanches. The only avalanche reported was a glide release on Seattle Ridge on the ‘Repeat Offender’ slide path. This path is a major hazard for motorized folks heading up Seattle Ridge and it is a relief that it released without any known human involvement. Unfortunately there are multiple glide cracks in this area, so just because one released does not necessarily mean the glide problem is resolved for the Seattle uptrack.

Glide release on ‘Repeat Offender’, which is the avalanche path that looms over the Seattle Ridge uptrack. Photo Brian Murphy 1.5.24

Today is looking like an ‘early bird gets the worm’ kind of day, with a brief calm period expected through midday before a strong storm front moves into the area. Winds will start off light, averaging 5-10 mph from the east, and gradually increase throughout the day. By this evening we are expecting east winds to average 40-60 mph with gusts of 80 mph+. Snowfall is expected to start around 3 pm today and continue throughout Sunday, with 15-30″ of new snow above 1000′ from Saturday afternoon through Sunday evening.

Our main concerns before the storm arrives are wind slabs at upper elevations and the lingering potential for a storm slab to release at the interface with the old snow surface. Yesterday’s windy weather likely formed wind slabs about 1′ deep along ridgelines at upper elevations. The increasing winds today will create a fresh batch of wind slabs 1-2′ deep. To monitor the development of fresh wind slabs keep an eye out for active wind transport along ridgelines and check for shooting cracks by getting off the skin track or trail in wind affected areas to get a feel for the snow.

The snow surface that was buried during Wednesday’s storm consisted of weak snow grains, like facets and surface hoar, which means it is still possible to trigger an avalanche at the interface between the storm layers. This interface is buried about 1.5-2′ deep in Turnagain Pass and Girdwood and closer to 2-3′ deep in Portage and Placer. Field observations the past few days have showed mixed results on whether this layer is still concerning or not, but since there is the potential to trigger a large avalanche on this layer we recommend a cautious approach to avalanche terrain today. You can use small, steep test slopes to check how well the new snow is bonding to the old snow surface and dig into the snow using hand pits or snow pits to get a little more information about this layer in the area you are travelling. If you want to avoid the problem entirely you can always stick to lower angle terrain.

Snowpit test that failed at the interface with the old snow surface about 2′ deep. Photo 1.4.24

The glide avalanche mayhem continues, with a fresh release reported above the Seattle Ridge uptrack yesterday. It is important to be vigilant and continuously assess the terrain above you to identify glide cracks. We recommend avoiding spending time underneath glide cracks altogether, but if it is unavoidable you can spread out your group and move as quickly as possible. When these avalanches release they take the whole snowpack, which results in a very large and destructive avalanche.

Large glide crack lurking under the Tincan Library. Photo 1.4.24