Avalanche Forecast
Issued: Jan 29th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
Friday's observations show storm slabs a bit tougher to initiate, but they're still releasing with light triggers. Keep your guard up at all elevations. This is a widespread, reactive avalanche problem.
Summary
Confidence
Weather Forecast
FRIDAY NIGHT: Cloudy with scattered flurries bringing up to 5 cm of new snow. Light to moderate southwest winds, increasing into the morning.
SATURDAY: Cloudy with continuing scattered flurries and up to 5 cm of new snow, increasing overnight. Light to moderate southwest wind, increasing over the day and becoming strong overnight. Alpine high temperatures around -7.
SUNDAY: Continuing snowfall bringing 10-20 cm of new snow, with new snow totals reaching about 20-40 cm, continuing overnight. Moderate to strong south winds. Alpine high temperatures around -4 with freezing levels rising to about 1400 metres.
MONDAY: Cloudy With continuing snowfall bringing 15-20 cm of new snow and 3-day snow totals to around 50-80 cm, easing overnight. Moderate to strong south winds, easing overnight. Alpine higfh temperatures around -4 with freezing levels to about 1400 metres.
Avalanche Summary
Preliminary reports from Friday show storm slabs reacting to skier traffic a bit more stubbornly, but still producing 40-50 cm-deep avalanches. This pattern will likely persist through Saturday before forecast weather takes things up a notch.
Observations from Thursday included numerous storm slab releases in the size 1-2 range (small to large). These included recent natural avalanches as well as ski cut and explosives results. All aspects and elevations were well represented, with our latest weak layer of surface hoar from late January, about 20-45 cm deep in reports, identified as a primary failure plane. Observations of the alpine are still limited.
With a bit more new snow adding to the avalanche problem discussed above, thick storm slabs are expected to remain sensitive to human triggering on Saturday.
Snowpack Summary
About 10 cm of new snow is expected to accumulate by the end of the day on Saturday. This will add to 25-50 cm of snow from a midweek storm which sits on firm wind slabs in exposed areas, on a melt-freeze crust in many areas around treeline and below treeline, on a sun crust on steep south-facing slopes, and on large surface hoar in sheltered areas.
There are potentially several more layers of surface hoar in the upper snowpack, with the most notable one down about 50-70 cm. This layer was buried in early January.
A couple of crusts surrounded by weak faceted grains are buried deep within the snowpack. The upper layer is 80 to 130 cm deep and the lower one is near the ground.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
Problems
Storm Slabs
25-50 cm of recent snow has formed reactive storm slabs in many areas and a bit more new snow may add to their sensitivity on Saturday. Slabs will probably be the most reactive in wind loaded areas, but sheltered terrain is equally concerning - here, slabs may be teetering on a fragile layer of surface hoar.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A deeper weak layer of surface hoar that was buried in early January may become reactive as loading from snow and wind continues.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Jan 30th, 2021 4:00PM
