Avalanche Forecast
Regions: South Coast.
There is uncertainty with what this major warming will do to the snowpack, but it could cause an avalanche cycle. Treat the hazard as HIGH and avoid avalanche terrain and overhead exposure if you observe natural avalanche activity.
Confidence
High - Confidence is due to a stable weather pattern; little change is expected for several days.
Weather Forecast
SUNDAY NIGHT: Clear skies, light northeast wind, treeline temperature 0 C, freezing level 2000 m.
MONDAY: Clear skies, light northeast wind, treeline temperature 4 C, freezing level 2300 m.
TUESDAY: Mix of sun and cloud, light to moderate northeast wind, treeline temperature 3 C, freezing level 2000 m.
WEDNESDAY: Clear skies, light northeast wind, treeline temperature 3 C, freezing level 2000 m.
Avalanche Summary
On Saturday, a small wind slab avalanche was triggered by a rider, as described in this MIN.
Looking forward, loose wet avalanche activity and cornice falls could be triggered with the warming trend. The potential of triggering wind slab avalanches remains possible in steep, alpine terrain.
Snowpack Summary
An intense warming trend will raise the freezing level to above the mountain tops.The warm air, coupled with strong radiation from the sun with clear skies, may rapidly weaken the snowpack and cornices. Expect to find moist or wet snow during the day, which could freeze into a melt-freeze crust overnight.
In the alpine, hard wind slabs may be found on all aspects due to variable wind directions. Recent wind has blown from the northeast, forming wind slabs in south to southwest terrain features. In sheltered terrain, about 30 cm of snow may overly a melt-freeze crust and potentially small surface hoar crystals.
The remainder of the snowpack is well-settled. The snowpack depth varies from around 300 to 400 cm around 1200 to 1400 m and tapers rapidly with elevation, with no snow below 700 m.
Terrain and Travel
- Extra caution for areas experiencing rapidly warming temperatures for the first time.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
- Carefully evaluate steep lines for wind slabs.
- Be aware of highly variable recent wind loading patterns.
Avalanche Problems
Loose Wet
The snowpack will undergo a rapid change as the freezing level rises and clear skies prevail. The most warming will occur on sun-exposed slopes during the heat of the day. However, the freezing level will be above the mountain tops, meaning that all aspects should be treated as suspect, particularly if you find moist or wet snow. Back off and avoid avalanche terrain if you start to notice natural avalanche activity.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2.5
Wind Slabs
An atypical loading pattern with wind from the northeast has formed wind slabs on terrain features that may not often have them. Use extra caution as you approach steep slopes in exposed terrain, particularly near ridge lines.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Cornices
Cornices are large at this time of year and they will undergo rapid weakening during this warming trend. Avoid travelling close to them while on ridges and limit your exposure on slopes beneath them.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 2.5 - 3.5