Friday January 8, 2021
Persistent Slab, Wind Slab
Travel & Terrain Advice
The past storm events have delivered high amounts of snow combined with strong winds take time to plan and choose supported terrain with little to no overhead hazard.
Be cognizant of snow conditions and utilize small slopes to test and investigate the recent storm snow and its reactionary properties.
Practice patience as the snowpack is still adjusting and settling from the past storm loading.
Careful and cautious route finding when transitioning from scoured areas into areas of wind loaded snow.
Avoid traveling below and above cornice features as they are large and touchy
Reports of widespread natural avalanches over the past 48 hours mostly size two with one unconfirmed size three on a North aspects at 1400 meters.
Mt Washington Avalanche control teams reported explosives triggering size 2 avalanches on unopened north aspect terrain down 30 to 110 cm in depth.
Please respect the avalanche/patrol team and workforce at Mount Washington, at no time is uphill travel or unsanctioned use of the private property permitted. We are lucky to have one of the least busy provincial parks in British Columbia and yes it may be a little more work than walking up a ski area run, its well worth the effort!
A layer of facets 20cm thick can be found down nearly a meter in the snowpack. Currently isolated testing of this layer is not producing results. This persistent layer is a concern because when it is trigger consequences will be severe. The likelihood may be low but the consequences are high, continual loading of the snowpack with the coming forecast storm is likely to increase the magnitude and perhaps reach a tipping point where sensitivity to triggering increases.
Location: Specific to large terrain features but found on all aspects in both the Alpine and at Treeline.
Possibility of triggering: Unlikely to Possible to both natural and human triggers.
Size: If triggered expect these avalanche to be large to very large size 2 to 3
Found on predominantly North aspects, this avalanche problem is likely to persist as wind transport is forecast to continue to load a variety of surfaces that include below 1500 meters a crust and above this elevation old storm snow.
Location: Predominantly on north aspects and found in both the Alpine and at Tree line.
Possibility: Triggering of this avalanche problem is likely to very likely from light loads such as skiers. Natural avalanches are possible.
Size: If triggered expect these avalanches to be small, and on isolated terrain features large, size 2.
Over the past week a strong storm system has delivered significant quantities of snow with extreme winds from the South East. Evidence of extreme wind transport of snow to North aspects is at all elevations.
Overall settled snowpack depths have been measured from 200 cm to 400 cm.
A variety of crusts exist in the upper snowpack. These crusts are producing sudden planar results during moderate testing.
The mid snowpack has a 20cm layer of facets that can be found down 100cm plus.
|Surface||Wind affected snow scoured on exposed South aspects with deep loading on North aspects.|
|Upper||100 cm plus of storm snow is over a crust below 1500 m and over old storm snow above 1500 m.|
|Mid||A 20cm layer of facets can be found down 100cm plus.|
|Lower||Well settled and dense.|
The previous storms have delivered a variety of precipitation amounts, the west side of the island received in excess of 150mm of precipitation, all of this falling as snow above 1100 to 1200 meters elevation. Winds where sustain at strong from the South East and South West with gusts in the extreme range (110 Km/Hr ).
Friday a storm track to the north west of the forecast region will deliver to the island mountains , moderate precipitation, initially extreme winds and freezing levels to 1000 meters. Saturday looks like a cooling trend with unsettled weather. The storm track reinvigorates on Sunday with increased wind and precipitation.
Friday: 10-20 cm of snow, Winds Strong to Extreme from the South East becoming light South West, Freezing levels to 1000 meters.
Saturday: No new snow, Winds Light Moderate from the South West, Freezing levels near sea level.
Sunday: 20-30 cm of snow , Winds Moderate from the South West, Freezing levels to 1000 meters.
Posted on Friday January 8, 2021 by Jesse Percival