Avalanche Forecast
Issued: Mar 5th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Wind Slabs and Loose Wet.
rbuhler,
Avalanche Canada
A weak crust/facet layer remains a concern, especially in the north of the region. The layer is expected to be most reactive on shaded aspects around 1600-2000 m. Check out the recent forecaster blog for more details.
Summary
Confidence
Weather Forecast
A ridge of high pressure brings one more day of dry and sunny conditions for Sunday before conditions change on Monday.
Saturday Night: Mainly clear, light to moderate N wind, freezing levels 600-1200 m.
Sunday: Mainly sunny, light to moderate N wind, freezing levels climbing to around 2000 m.
Monday: Mainly cloudy with flurries in the afternoon, light to moderate NW wind, freezing levels reaching around 1500 m in the afternoon.
Monday night and Tuesday: Snowfall up to 10 cm, light to moderate NW wind, freezing levels around 800 m.
Avalanche Summary
On Friday, numerous loose avalanches were observed on steep sun-exposed slopes. No new slab avalanches were reported.
On Thursday, some natural wet slabs up to size 1.5 were reported in the north of the region as well as several natural wind slabs. Natural loose avalanches were also observed on steep sun-exposed slopes. In the Coquihalla, a few glide slab avalanches were observed.
This MIN report from the north of the region on Thursday describes whumpfing and shooting cracks which suggests persistent weak layer buried late-February is reactive in this part of the region.
In the neighbouring Sea to Sky region, numerous natural and human-triggered persistent avalanches have been observed between Wednesday and Friday which failed on the February crust/facet interface. The snowpack structure is expected to be similar in the north of the Inland region and the persistent slab problem should be expected until proven otherwise.
Snowpack Summary
A surface melt-freeze crust is now expected on all aspects below around 1500 m and on sun-exposed slopes into the alpine. Dry surface snow is still expected on shaded aspects at treeline and in the alpine, and recent periods of moderate northerly wind may be redistributing this old storm snow and forming wind slabs in exposed high elevation terrain.
Two weak interfaces from February are typically down 40-60 cm in the north of the region and as deep as 80 cm in the Coquihalla. In the north of the region, these layers are expected to be very close together and may be acting as a single weak layer like the neighbouring Sea to Sky. In the south of the region, there may be 30-40 cm of snow between the layers which may have resulted in the layers being less reactive compared to the north. While the layers have not produced the same widespread avalanche activity compared to the neighbouring Sea to Sky region, a persistent slab problem still remains a major concern, especially in the north of the region where the snowpack structure is expected to be quite similar. In the Sea to Sky, the interface has been most reactive on shaded aspects between 1600 and 2000 m. There were also some avalanches on southerly aspects earlier in the week but with each subsequent day of melt-freeze conditions, the persistent problem is becoming less likely on sun-exposed slopes.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Problems
Persistent Slabs
In the adjacent Sea to Sky forecast region, a persistent weak layer of facets on a crust exists 30-60 cm below the surface and has been touchy to human triggers, especially on shaded aspects around 1600-2000 m elevation.
There has been limited observations of avalanches on this layer reported in the South Coast Inland region. However, the snowpack structure is similar in the north of the region and there are observations that suggest the layer remains reactive. It should remain on your radar and a conservative approach is recommended on shaded aspects around treeline.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Watch for recent or ongoing wind slab formation on Sunday. Periods of moderate wind from the north may be enough to develop reactive new slabs in exposed terrain at higher elevations.
Lingering cornices may become weak during the heat of the afternoon. Cornices are most likely on north and east aspects in the alpine.
Aspects: East, South East, South, South West, West.
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 6th, 2022 4:00PM
