Avalanche Forecast
Regions: East Island, North Island, South Island, Vancouver Island, West Island.
Amounts and reactivity of our new snow at upper treeline and especially alpine elevations remain uncertain, but the likelihood of lingering wind slab hazards will increase in step with the dry accumulations you encounter on your ascent. Expect new snow to shed eagerly from any steep slopes that see the sun on Wednesday.
Confidence
Moderate
Avalanche Summary
Numerous natural wet loose releases were observed on Monday at treeline and below as rain saturated our recent storm snow. Alpine observations are lacking, however with precipitation falling as snow, higher elevations likely experienced some degree of natural avalanche activity during the most recent storm pulse.
Looking forward, the highest elevations of the island where dry snow has accumulated remain a concern for wind slab potential. Cooling temperatures should have by now locked the snowpack in place where precipitation has instead fallen as rain.
Snowpack Summary
20-50 mm of precipitation fell in the region from Monday through Tuesday, faling mostly as rain and heavily favouring the south and west of the island. Above about 1600 m there is some uncertainty about how much dry snow actually materialized from the storm across the island. Is it 15 cm? 40?
The new snow added to (while rain saturated) as much as 70 cm accumulated above 700 m from the previous storm pulse at the end of last week.
All this snow and rain has fallen above a melt-freeze crust. The crust is up to 10 cm thick at lower elevations and tapers to 1 cm thick on shaded or high elevation terrain. Other than a few cm of softer snow recently found immediately below this crust, the remainder of the snowpack is strong and well bonded.
Weather Summary
Tuesday night
Cloudy with easing snowfall bringing a final 5 cm of new snow. Strong southwest winds, easing into the morning. Freezing levels bottoming out at around 700 m.
Wednesday
Clearing in the morning before clouding over again in the afternoon. Trace snow accumulations. Light southwest winds shifting southeast and increasing in the afternoon/evening. Treeline high temperatures around -1 with freezing levels to 1000 m.
Thursday
Cloudy with continuing snowfall from overnight bringing 15-25 mm of precipitation, including overnight snowfall but increasingly falling as rain to about 1200m. Strong to extreme south winds. Treeline high temperatures around 0 with freezing levels rising to 1400 m.
Friday
Cloudy with flurries bringing 5-10 cm of new snow. Strong south winds easing to light northeast. Treeline high temperatures around -1 with freezing levels to 1000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Make observations and assess conditions continually as you travel.
- Carefully evaluate steep lines for wind slabs.
- Brief periods of sun could quickly initiate natural avalanche activity.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Avalanche Problems
Wind Slabs
10-20 cm of new snow (or more?) from about 1500 m to the alpine likely formed wind slabs in specific leeward terrain features toward the end of the Monday-Tuesday storm. Observations of the distribution and reactivity of new slabs are lacking, so cautious approach is warranted.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Loose Wet
Sunshine is uncertain for Wednesday, but any steep slopes holding new snow that do catch a glimpse of it will be eager to shed surface snow.
Aspects: South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1.5