Conditions Summary for Spearhead and Duffy Lake Areas of the South Coast Ranges

South Coast Backcountry Sea to Sky

Darek Glowacki , Sunday 7th February, 2021 5:45PM

The following weather and avalanche conditions summary is brought to You by the participants of the ACMG Training and Assessment Ski Touring Program which took place in the Spearhead and Duffy Lake regions during the week of Jan 31 to Feb 6th.

WEATHER SUMMARY

Throughout the past week there was a storm system that produced 50cm to 70cm of settled snow in the Spearhead area. Daytime temperatures averaged around -6 at tree line for the majority of the week and freezing levels hovered around 1200m. The sun came out on Feb 3 and created a thin sun crust on solar aspects. On Feb 5th, skies were clear and solar radiation was quite strong. Both days solar input created point releases on steep solar aspects. Winds were strong on feb 1 from the north east and tapered to consistent northerly winds until feb 6 affecting the snow in a variety of ways. For more info, see notables below.

Spearhead and Duffy Lakes Snowpack summary

Within the top 10cm of this recent storm snow there is a recently buried surface hoar layer. The recent storm snow was accompanied by strong winds in the Alpine and at Treeline from variable directions that has redistributed the storm snow into wind slabs in lee terrain, ridge tops and cross loaded gullies. At ridge top the winds have also been building fresh cornices that require caution. After the storms the mid winter sun came out and created a breakable crust on steep solar aspects. This all sits on top of old wind affected surfaces that are composed of weak surgery crystal, also know as facets, crusts on solar aspect and lower elevations, and surface hoar in protected areas. Below this is a well settled snow pack with a lingering faceting crust layer that is not currently producing avalanches, but given a very large trigger like a cornice, could be reactive.

The Duffey Lake area received similar weather and changes to its snowpack as the Spreadhead area, however the recent storm snow is 40-50cm deep. Other than that, there is no direct observations with regards to the recently buried surface hoar that was noted in the Spearhead area, so distribution is uncertain. Though we suspect it would be there as well.

NOTABLES:

On February 4th there was a skier remote avalanche on the south east aspect of Spearhead Col that produced a size 1.5 avalanche within a windslab interface at 2300m. Later in the day a Skier Accidental avalanche occurred on a SE aspect again. The crown was 10m wide and 10-15cm deep. The slope was over 35 degrees. No injuries were sustained.

On February 5th there was a Skier Accidental size 1 on the approach to the Armchair Glacier. South east Aspect at 2050m. Width was 40m and length 30m. Depth 10cm. No injuries were reported.

Also on the lower slopes of the Armchair Glacier we found a compression test moderate (14) sudden planar shear down 50cm on decomposing surface hoar on a NE aspect at 1800m. This caused us to change our route choice for the end of the day ski run.

Overall great ski conditions at treeline and below with some notable wind effect in the alpine areas.

ACMG TAP Guide Training Students and Instructors.

Source: Mountain Conditions