Avalanche Forecast
Issued: Mar 23rd, 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.
bchristie,
Avalanche Canada
Continually evaluate conditions as you travel through terrain. Avalanche danger is improving, but temperatures remain warm and riders have recently triggered avalanches on a persistent weak layer.
Summary
Confidence
Weather Forecast
WEDNESDAY NIGHT: Variable cloud cover across the region. Light rain/snow expected, possible heavier on the western side of the region. Light southwest ridgetop winds trending to strong in the high alpine. Freezing level falling to around 1400 m.
THURSDAY: Mostly Sunny. No new rain/snow expected. Light variable winds, with some periods of strong northwest in the high alpine. Freezing level rising to around 1750 m.
FRIDAY: Partly cloudy with light rain/snow. Light southwest ridgetop winds, trending to moderate northwest in the high alpine. Freezing level around 750 m overnight, rising to 2000 m through the day.
SATURDAY: Mostly cloudy. Possible light rain/snow. Freezing level around 2200 m. Light southwest ridgetop wind trending to strong in the high alpine.
Avalanche Summary
On Tuesday and Wednesday, widespread loose wet avalanches were reported due to warm temperatures and/or sunshine (mostly size 1-2, a couple size 2.5 or 3). East of Kaslo, a naturally triggered size 2.5 windslab was reported on a north aspect in the alpine.
Several natural and one human-triggered wind slab occurred on Sunday and Monday in the alpine and treeline (size 1-2).
Several notable human-triggered slab avalanches occurred last week, suggesting that the recent snow is bonding poorly to the underlying layers. These occurred on a range of aspects above 2000 m, with the most notable reactivity observed on south-facing aspects. Most slabs were small in the top 20 to 30 cm of snow (size 1), but one larger 70 cm thick slab was remotely triggered from below by a group of skiers (size 2). This avalanche occurred on a south aspect at 2250 m. (read more in this blog).
Snowpack Summary
30-70 cm of settling storm snow exists at higher elevations. Snow depths taper significantly with elevation, with moist and crusty surfaces below 2000 m and on south aspects into the alpine.
In some areas, last week's snow is well bonded to old crust layers, while in other areas the snow has settled into a reactive slab above weak layers around the crusts. At this point, it appears persistent slab problems may exist in the deeper snowpack areas along the western side of the range. The lower snowpack is generally well bonded.
Terrain and Travel
- If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Be alert to conditions that change with elevation.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
- Avoid steep slopes when air temperatures are warm, it is raining, or solar radiation is strong.
Problems
Persistent Slabs
This is mainly a concern in the western part of the region that received greater snowfall amounts last week. 30 to 70 cm of settled storm snow has shown evidence of forming a persistent slab above weak layers. The most reactivity has been observed on south-facing aspects, with reports of a poor bond to underlying sun crust layers. Weak surface hoar crystals may also exist in isolated areas on north-facing slopes.
This layer is getting harder for riders to trigger, but it is possible that it could still produce large, surprising avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Westerly winds are expected to continue redistributing available snow into wind slabs in lee features in the alpine and treeline.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Freezing levels are falling overnight, but the surface snow may not solidly refreeze at lower elevations. Paying close attention to how thick and supportive the surface crust is throughout the day will help you avoid any lingering wet loose avalanche problems below treeline.
Also be cautious on and under alpine avalanche terrain when the sun is cooking it.
Aspects: All aspects.
Elevations: Alpine, Below Treeline.
Likelihood
Expected Size
Valid until: Mar 24th, 2022 4:00PM
