Chilkat Pass

The road has finally re-opened however, new snowfall and lack of access brings a high uncertainty of conditions. An assessment mindset will be needed to safely gather information about recent storm snow and winds that have affected this area. Please see the Transtional Zone forecast for more current and verified information.

The pass did not stay cold enough to fully avoid the "end of year" (EOY) melt-freeze crust. Three Guardsman weather station on December 30th temperatures got above freezing. Nearby in the Transitional Zone, the crust has been confirmed up to 4000'.  When we re-enter the Chilkat Pass, the end of year crust is one of the things we will need to be on the look out for.

From Transitional Zone: Weak angular snow grains known as facets are present above and below the EOY crust and could increase propogation potential. Although triggering a slide below the crust remains unlikely, cold temperatures slow the healing process and drive faceting, or the weakening of these layers around the crust and that's what we have happening now.  This can occur at a microscopic level due to temperature gradients being so small they are only detectible by infrared around a melt-freeze crust. We should treat these layers as guilty until proven innocent and continue to monitor, track, and assess stability on a slope-by-slope basis. Melt-freeze crusts have played a role in avalanche accidents across our forecast zones and our state. Use safe travel techniques by only exposing one person to a slope at a time, avoid grouping up in run-out zones and re-consider islands of safety to truly limit your group's exposure.

What we know about the EOY crust is that above freezing temperatures up to 4,000' due to an inversion at the end of the storm on Decemer 30th in the Transitional zone, caused the formation of a thick ( 1" +/-), widespread EOY melt-freeze crust.  The strength of this layer, thick and thiness is variable due to  duration and intensity of the EOY event and is elevation dependent due to a cooling trend that followed the increase in temperature at elevation.

Other layers to note are from earlier this season, and are now more than a meter deep. These include a few melt-freeze layers that are present throughout the snowpack at all elevations and aspects. These layers formed during other warming, or rain on-snow events and have mostly been found to be healing but could fail and produce a very unlikely though larger avalanche. Our overall warm and wet temperature regime through the season has helped slow the development of persistent weak layers (PWL's) in the snowpack. However at higher elevations and further inland these grain types can exist, and will require continued assessment. 

The people you go out with, the way you communicate, and the way you practice risk reduction as a team throughout the day is equally important as the conditions.

Help us gather information about weather, snowpack, and avalanche activity by reading and submitting field observations. Useful observations can be anonymous and include: 

• Natural or human-triggered avalanche activity
• Signs of instability: Cracking, collapsing, or whumphing
• Red Flag Weather: Precipitation, wind loading, warming temperatures and rain-on-snow
• Surface hoar growth, snow depth, persistent weak layers, etc
• Snow stability tests, or pit result and location, elevation, aspect, etc 

Were you caught, carried, injured or buried in a slide? We are all human and can benefit from lessons learned, please report incidents to Haines Avalanche Center staff confidentially.