Avalanche Forecast
Issued: Jan 18th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Conditions may be tricker than what meets the eye. Riders could be drawn to sheltered areas around treeline to avoid wind slabs at upper elevation. Buried surface hoar has been active in treeline terrain in recent days, and has the potential to produce large and surprising avalanches. Avoid steep treeline openings and don't let powder hunting draw you into dangerous terrain.
Summary
Confidence
Moderate
Avalanche Summary
Earlier in the week, several size 1 to 2 avalanches were reported at Hankin, Ashman, and the Babines. These avalanches were easily triggered by the weight of a rider. They were sliding on a layer of weak, feathery surface hoar crystals, 20 to 30 cm below the snow surface. One of these slabs stepped down to a layer of weak, sugary, facetted crystals that were buried on December 23rd.
Looking forward to Thursday, pockets of wind slabs at upper elevations and persistent slabs in sheltered treeline openings should be your main concern.
Snowpack Summary
Southwest winds are redistributing 20 to 30 cm of low-density surface snow into fresh wind slabs in the alpine and treeline. Yesterday's sun and warm temperatures formed a sun crust on steep solar aspects and on all aspects at lower elevations.
A weak layer of surface hoar formed in early January is now down 30-40 cm. This layer is most prevalent in shaded and sheltered areas at treeline.
A weak layer of facets that formed during the arctic outbreak in December is buried 50 to 80 cm deep. Observations suggest it is fairly widespread, but rounding and gaining strength, and is unlikely to be triggered under the current conditions.
Weather Summary
Wednesday night
Clear periods, isolated flurries. Alpine temperature drop to a low of -8 °C. Ridge wind west 20 km/h gusting to 60 km/h. Freezing level at valley bottom.
Thursday
Mainly cloudy, light flurries. Alpine temperatures reach a high of -4 °C. Ridge wind west 20 km/h gusting to 60 km/h. Freezing level 800 metres.
FridayCloudy with snowfall, 2-10 cm accumulation. Alpine temperatures reach a high of -1 °C. Ridge wind southwest 20 km/h gusting to 80 km/h. Freezing level 1500 metres.
SaturdayA mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -4 °C. Ridge wind west 30 km/h gusting to 65 km/h. Freezing level 1100 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Problems
Wind Slabs
Southwest winds will continue to redistribute the surface snow into fresh wind slabs in the alpine and treeline.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Previous storm snow has shown evidence of settling into a more cohesive slab over a layer of weak, feathery surface hoar crystals. Be particularly cautious in open areas at treeline, where this weak layer of surface hoar is most likely to be preserved below these slabs.
This MIN Report does a great job of explaining how the avalanche problem might present itself.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 19th, 2023 4:00PM
