Avalanche Forecast
Issued: Mar 4th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Cornices and Loose Wet.
rbuhler,
Avalanche Canada
Lingering storm slabs may still be reactive on steep, unsupported slopes or where the storm snow overlies a weak crust/facet layer. Watch for new wind slab formation with the potential for periods of moderate northerly wind on Saturday.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.
Weather Forecast
A ridge of high pressure brings dry and sunny conditions for the weekend.Â
Friday Night: Clear, light N wind, freezing levels 800-1200 m.
Saturday: Sunny, light to moderate N wind, freezing levels reaching around 1500 m.
Sunday: Mainly sunny, moderate N wind, freezing levels potentially reaching around 2000 m in the late afternoon.
Monday: Mainly cloudy with a chance of flurries, strong NW wind, freezing levels around 1000 m.
Avalanche Summary
No new avalanches were reported on Thursday. However, widespread pinwheeling was observed on steep slopes on all aspects and elevations. Just north of the region in the Tantalus, widespread avalanche activity was observed between Wednesday afternoon and Thursday morning.Â
On Wednesday, wet loose avalanches up to size 1 were easily triggered by skiers. No new natural avalanche activity was reported.
On Tuesday, a skier triggered storm slab size 1 was reported from a northeast aspect at treeline. Wet loose avalanches were easily triggered below treeline up to size 1.Â
On Monday, several storm slabs were reported up to size 2. This followed a widespread natural storm slab avalanche cycle on Sunday. Skier-controlled storm slabs were triggering remotely and propagating widely at treeline and below as shown in this MIN report. Natural avalanche activity will likely continue through Wednesday with reactive storm slabs in the alpine and upper treeline and loose wet avalanches below treeline.
Snowpack Summary
A melt-freeze crust is now expected to be capping the snowpack on all aspects at lower elevations and on sun-exposed slopes at higher elevations. Dry surface snow may still exist on high elevation northerly aspects.Â
A weak interface from mid-February can be found 30-60 cm deep. This interface includes a sun crust, facets, and surface hoar. This interface was bonding poorly at the beginning of the storm but has become less of a problem now where the snowpack is capped by a robust crust. At higher elevations where the snowpack is not capped by a crust, the interface may still be reactive. Check out the Sea to Sky Forecast and this forecaster blog to learn more about the recent reactivity on this layer which is still reactive just north of the region.
50-80 cm below the surface, a 30 cm thick crust caps the underlying snowpack which is well settled and strong.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Cornices become weak with daytime heating or solar exposure.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Problems
Storm Slabs
Storm slabs may still be reactive to human triggering, especially in steep or convex terrain and wind-loaded areas in the alpine. These slabs may persist for longer than normal where they sit above a firm crust which potentially has weak facets above it. New wind slabs may form on Saturday with moderate northerly winds.
While we are generally not expecting the storm snow to transition to a persistent slab problem in most of the region including the North Shore, other parts of the region may be more similar to the adjacent regions. Check out the new forecaster blog for details on the persistent problem in adjacent regions.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Looming cornices have grown large during the recent storm. They could still pose a threat from above or below, and are expected to become weak when the sun is at its strongest.
Aspects: North, North East, East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
With each subsequent day of melt-freeze conditions, loose wet avalanches will become less likely. However, extra caution is still recommended on steep sun-exposed slopes during the heat of the afternoon. Where the crust is breaking down or non-existent, loose wet avalanches will be more likely.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 5th, 2022 4:00PM
