Avalanche Forecast
Issued: Mar 22nd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
dsaly,
Avalanche Canada
Assess you line for wind slabs before committing to steep terrain. Convex slopes below ridge tops are the most likely places to trigger slabs.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
MONDAY NIGHT: Partly cloudy. Light west-northwest wind, alpine low -12C, and freezing level valley bottom.
TUESDAY: Sunny breaks with patchy clouds through the day. Light to moderate northwest wind, alpine high -4C, and freezing level rising to 1500 m.
WEDNESDAY: Cloudy with flurries, 5 cm. Light southwest wind, alpine high -3C, and freezing level rising to 1500 m.
THURSDAY: Unsettled with flurries, 5 cm. Light west wind, alpine high 0C, and freezing level rising above 1500 m.
Avalanche Summary
On Sunday, dry loose avalanches failed naturally and were reactive to skiers with fresh low density snow sliding on crusts or compact surfaces.
On Saturday, several natural size 1.5 wind slabs were observed on northeasterly aspects in the alpine. Size 2 slab avalanches were reported failing naturally on steep, south slopes (MIN report and deeper snowpack here). Sluffing and dry-loose avalanches were reported in steep terrain.
A few small loose wet avalanches were reported Wednesday through Friday on solar aspects into the alpine. A small wind slab was also reported from a high elevation east facing aspect last Thursday.
Snowpack Summary
South-southwesterly winds have impacted loose snow developing slabs in immediate lees. 5-15 cm fresh snow covers dry settled snow on northerly aspects above 1800m, and crusts on solar aspects and lower elevations. Loose snow is sluffing easily on the crust. Large cornices loom over alpine ridgetops. Below 1300 m, the snowpack is moist.
A persistent weak layer of facets 40-60 cm deep that was buried in mid-February was reactive in the north of the region earlier this month but since the first week of March, only a couple of avalanches have been reported on this layer resulting from large triggers such as cornice fall. There are several other weak layers deeper in the snowpack composed of old surface hoar, facets and/or crusts, all of which have been recently unreactive.
Terrain and Travel
- Be alert to conditions that change with elevation, aspect and exposure to wind.
- Carefully evaluate steep lines for wind slabs.
- Minimize your exposure time below cornices.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Wind Slabs
Recent southwest winds and fresh snow formed wind slabs in lee terrain features. Now in a west-northwesterly flow, winds may may "reverse load" slopes, building fresh wind slabs on more south and easterly aspects. Steep, convex slopes below ridges are the most likely places to trigger these slabs.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Cornices
Where cornices exist they pose a threat both from the potential to collapse under your feet (or machine) and from the potential to send large chunks of snow far down a slope. If anything can trigger the more stubborn persistent weak layers it's a large falling cornice.
Aspects: North, North East, East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 23rd, 2021 4:00PM
