Observation: Chugach State Park

Location: Gordon Lyon

Route & General Observations

Arctic Valley Trailhead up Gordon Lyon to 4000′ on generally SW to East aspects

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Observer Comments

Some small mid-storm avalanches below a corniced ridge in north bowl (as previously reported) and potential small debris piles stopping mid slope in the South Fork valley. These slides all appeared to be natural, and were covered by snow at the end of last week's big storm!

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.

Clear skies with valley fog down low over Anchorage
Temps in the teens - 20s at ridgeline
Generally calm, occasional light winds from the North or SW
The next storm approacheth!

Snow surface

Surface hoar - 2-4mm - covered the entirety of our route, ridgeline to valley bottom. This generally sat on soft fist hard snow ranging from a few centimeters deep at ridgeline to basically the entire snowpack of 40-50cm below 3000' in non-wind affected areas. Ski penetration of 30cm (1') in wind protected areas; 5-20cm in places that received some wind during the storm.


A breakable, 1cm thick melt freeze crust could be found in the middle of recent storm snow, down ~20cm from the surface at the parking lot elevation (2600'). This crust got thinner and disappeared completely at 3300'. Above 3000' some mid-storm wind produced small pockets of wind slab at ridgeline and occasionally mid-slope as well, but generally these slabs were covered by soft new snow. Below 3500', the snow in the bottom 1/4 of the snowpack was moist, but otherwise it was dry.

On the SW to East slopes below 3500' that we traveled on, multiple hand pits/ski pole probes found just the recent storm snow, with no advanced facets or crusts that formed prior to last week's storm. Above 3500', spatial variability was high, but twice on SW and N aspects a concerning layer of fist hard 1-2mm facets was found at the base of the snowpack, with a 1cm thick pencil hard melt freeze crust above it and a thicker melt freeze crust below it. This layer of facets was 6cm thick at the pit location, on a slightly wind loaded N aspect a few hundred yards from the top of Gordon Lyon. As reported in the pit image below, an ECT failed with propagation after just 7 taps, and CTs failed at 9 with a very noticeable sudden collapse fracture character as well. All that said, a vast majority of ski pole probes/quick hand pits above 3500' didn't find this poor structure along our route.

Photos & Video
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