Avalanche Forecast
Issued: Feb 28th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
ahanna,
Avalanche Canada
Watch for signs of instability in wind affected areas and steep openings in the trees where surface hoar may exist under the recent snow.
Summary
Confidence
High - The snowpack structure is mostly striaghtforward and not unusually variable.
Weather Forecast
Sunday night: Flurries bringing a trace of snow. Freezing level 800 m. Wind moderate below 2000 m, strong southwest ridgetop wind.
Monday: Flurries bringing a trace of snow. Freezing level 1600 m. Wind moderate below 2000 m, strong southwest ridgetop wind.
Tuesday: Flurries bringing a trace of snow. Freezing level 1500 m. Moderate southwest wind.
Wednesday: Sunny. Freezing level 1700 m. Light to moderate southwest wind.
Avalanche Summary
On Saturday, wind/storm slabs were mainly stubborn to human triggers, with one report of a size 1.5 ski cut. Large explosive loads produced size 2-3 results at Kootenay Pass. A few of these large avalanches are suspected to have stepped down to the January layer described in the snowpack summary.
Snowpack Summary
At upper elevations, 20-40 cm of recent snow is likely undergoing continued transport by strong southwest wind. Recent wind direction has been predominantly westerly with some southerly or northerly components, depending on elevation. This recent snow may sit over a layer of small surface hoar crystals in isolated areas around treeline.
A couple of persistent layers exist 60-80 cm and 80-150 cm below the surface, having formed in mid-February and late January, respectively. These are composed of combinations of surface hoar, crusts and facets. The depth of these layers mean that they require very large loads to trigger, but when triggered they produce large, destructive avalanches. This has been demonstrated this weekend in Kootenay Pass. So while they are currently difficult to trigger in a recreational context under the current conditions, these layers remain on our radar.
Shallow snowpack areas in the east of the region may harbor a facetted basal snowpack as described in this MIN report. This structure is often a constant for thin snowpacks and can be managed with good travel habits of avoiding shallow rocky areas where the snowpack transitions from thick to thin.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Start on smaller terrain features and gather information before committing to bigger terrain.
Problems
Wind Slabs
Reactive wind slabs may be found in atypical terrain features. Wind direction has been predominantly westerly but may also may have southerly or northerly components, depending on elevation.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 1st, 2021 4:00PM
