Avalanche Forecast
Issued: Mar 22nd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Deep Persistent Slabs and Cornices.
rbuhler,
Avalanche Canada
Solar-triggered loose wet avalanches and cornice releases remain a concern. Use extra caution around sun-exposed slopes during the heat of the afternoon.
Human triggering of the lingering deep persistent layer still remains possible in thin, rocky snowpack areas.
Summary
Confidence
Avalanche Summary
On Tuesday, numerous natural loose wet avalanches up to size 2.5 were reported between 2000 and 2700 m elevation. One of these triggered a size 3 deep persistent avalanche at 2600 m elevation which failed down 100-200 cm on the November basal layer. A couple of other natural size 2.5 slab avalanches were also reported. One natural cornice release was reported on a SE aspect at 2300 m and several other cornices were triggered with explosives. None of these cornice releases triggered slabs.
On Monday, numerous naturally triggered wet loose avalanches up to size 3 (very large) were reported on steep sunny aspects in the alpine. A helicopter landing on a ridge remotely triggered a size 2 wind slab on the steep northerly alpine slope below. A couple of human-triggered size 1 wind slab avalanches were also reported on northerly aspects in the alpine.
Snowpack Summary
Expect to find a melt-freeze crust on the surface of all aspects at treeline and below, and on sunny aspects in the alpine. Depending on the timing of the incoming cloud cover, solar radiation may break down the crust on sunny slopes throughout the day on Thursday.
30-50 cm down there is a sun crust on sunny aspects and surface hoar (3-10 mm) on isolated shady and sheltered slopes.
The mid-snowpack is generally strong but the lower snowpack is a different story.
The November facets are still prominent at the base of the snowpack. They are showing signs of improving but this layer remains a significant concern for human triggering in rocky, shallow, or thin-to-thick snowpack areas at treeline and above. Small avalanches and cornice falls also have the potential to trigger this deep layer.
Weather Summary
Wednesday Night
Clear, ridgetop winds southwest 10-20 km/h, treeline low around -10 °C.
Thursday
A mix of sun and cloud, ridgetop winds southwest 10-20 km/h, freezing level reaching around 1800 m.
Friday
Light snowfall up to 10 cm, ridgetop winds southwest 10-25 km/h, freezing level reaching around 1400 m.
Saturday
A chance of light flurries, ridgetop winds northwest 10-20 km/h, freezing level reaching around 1300 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Cornice failure may trigger large avalanches.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Loose Wet
Depending on the timing of the incoming cloud cover on Thursday, strong March solar radiation still has the potential to increase the likelihood of wet loose avalanches on sunny aspects in the alpine.
Aspects: South East, South, South West, West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth, but large triggers such as cornice failures or smaller avalanches in motion have the potential to produce very large avalanches with surprisingly wide propagation. Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices may become weak during the heat of the afternoon. Use extra caution when travelling on ridges and avoid slopes with large cornices overhead during the heat of the afternoon.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 23rd, 2023 4:00PM
