Friday February 8, 2019
Wind Slab, Loose Dry
Travel & Terrain Advice
Exercise caution if you are choosing to travel at treeline and Alpine elevation bands this weekend. Southerly Aspects will receive a substantial amount of wind driven snow load and create wind slabs. Given the wind speeds forecasted for Friday and Saturday, size 2 avalanches could likely be initiated on terrain below ridges, in depressions and at mountaintop below cornices. Keep your eyes peeled for cornice development in an atypical (reverse loading) format and expect south aspects to produce avalanches. Beware of snow cracking underfoot or under your snowmobile and take this as a clear indication of unstable snow. Find supportive and well anchored terrain in the trees, away from open wind exposed slopes. If you are travelling at higher elevation bands, cautious route finding and careful decision making and terrain selection will make for a successful outing.
A relatively calm period of weather and lower avalanche hazard will shift on Friday February 8th as moderate winds will begin to move snow from North slopes onto southerly aspects. Saturday’s strong forecasted winds could create wind slabs up to size 2+ on southerly aspects. This trend of wind slabs will continue foir the duration of the weekend as strong winds will persist throughout Saturday. In wind protected areas, loose unconsolidated ‘sloughs’ (size 1) can be initiated on steep unsupported terrain.
Moderate snow transport begins Friday February 8th. More substantial snow transport will begin Saturday on the North end of the Island around Mt Cain where strong sustained winds are predicted throughout much of Saturday. Given the approximate 30+cm of light dry powder snow currently available for transport, we could expect likely triggering of avalanches (size 2+) on southerly aspects where wind slabs will linger throughout the weekend.
Loose dry ‘sloughs’ could pose a threat to recreational users travelling on steep unsupported terrain. There is currently 30 cm of unconsolidated snow that sits atop a firm melt freeze crust. Expect ‘sloughing’ and small size 1 avalanches as a result of this unconsolidated snow on steep unsupported terrain.
The snowpack is extremely well bonded. There remains 10 - 30 cm of light dry powder snow sitting on a very consolidated snowpack that is composed of a number of melt freeze and ice crusts. If the cold temperatures continue to persist, we may begin to see surface faceting due to these cold temperatures. However at this time the snowpack remains very well bonded.
|Surface||10cm - 30 cm of light, fluffy dry snow and is bonding poorly to crust below|
|Upper||thick 10cm melt freeze crust at treeline and a 3cm thick melt freeze crust above treeline|
|Mid||Well bonded mid-pack that does include two weaker (PWL) layers that are currently un-reactive (Facet layer and Surface hoar layer)|
Cold temperatures and clear weather has persisted throughout the week.
Friday: 3 to 5 cm of new snow, Temperature -1 to -17 degrees, Strong Winds from the North beginning late morning, Freezing Level 300M
Saturday: no new snow, Temperature -8 to -21 degrees, Strong to moderate Winds from the North, Freezing Level 0M
Sunday: no new snow, Temperature -5 to -17, Light to Moderate Winds from the North, Freezing Level 0M
Posted on Friday February 8, 2019 by Ryan Shelly