Avalanche Forecast
Issued: Nov 25th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
dsaly,
Avalanche Canada
Keep your head up as you gain elevation and exposure to the wind. Forecast snowfall amounts vary through the region, expect slabs to be more reactive as snow stacks up.
Summary
Confidence
Weather Forecast
Thursday night: Flurries and snow, 5-30 cm. Southwest winds, 35-45 km/hr. Alpine temperature low -6C. Freezing level 1000 m.
As this system tracks through the Purcells forecast snowfall amounts fall quickly west to east. The western peaks and areas around the Bugaboos may accumulate over 30 cm overnight and into Friday with significantly less reaching the Rocky Mountain Trench.
Friday: Snow and flurries, 5-20 cm. Southwest winds, 45-50 km/hr. Alpine temperature high -3C. Freezing level 1400m.
Saturday: Mostly cloudy with sunny breaks. Southwest winds 15-30 km/hr. Alpine temperature high -1C. Freezing level 1400 m and rising.
Sunday: Wet Flurries and snow, 10-25 cm. Southwest winds 45-60 km/hr. Alpine temperature high 1C. Freezing level 2100 m.
Avalanche Summary
On Tuesday, November 23, explosives triggered a large (size 2) avalanche which failed on facets at the bottom of the snowpack. This was a reloaded slope (already avalanched this season) and occurred on a north aspect at 2270 m.
On Monday, November 22, explosives triggered a few small (size 1) wind slab avalanches in immediate lee features.
Snowpack Summary
10-25 cm of recent snow is being transported by wind and developing slabs in lee features. The mid-November rain crust is down 30-50 cm, and has been reported up 2100 m.
A couple of crusts are found in the lower snowpack: A thin rain crust from early November is found 40 cm above the ground in deeper snowpacks and at the ground in shallower areas, it likely does not exist above 2300 m. A melt-freeze crust and facets from October is at the base of the snowpack, and possibly only exists above 1900 m.
Snowpack depths range from 50-140 cm at treeline elevations, and exceed 200 cm in the high alpine. Deeper snowpacks are found around the Bugaboos and northern parts of the forecast region. Snowpack depths decrease rapidly below 1700 m.
Early season hazards are very real right now, be wary of thin/shallow snowpacks, rocks, stumps, creeks, and other sharks hidden under a dusting of snow.
Terrain and Travel
- Be alert to conditions that change with elevation and wind exposure.
- Avoid areas where the snow feels stiff and/or slabby.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.
Problems
Storm Slabs
Storm slabs will form with new snow and wind. The most reactive deposits will be around ridgelines and in lee-ward terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak snow at the base of the snowpack has produced a few recent avalanches. We need more information on the distribution of this layer but we suspect it only exists at high treeline elevations and into the alpine.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Nov 26th, 2021 4:00PM
