Avalanche Forecast
Issued: Mar 16th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Wind Slabs and Deep Persistent Slabs.
shorton,
Avalanche Canada
Avalanches will become more likely as the snow heats up. Be very cautious around cornices and large slopes getting hit by the sun.
Summary
Confidence
High - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
A ridge of high pressure brings clear dry conditions for the week.
MONDAY NIGHT: Clear skies, light northwest wind, freezing level drops to valley bottom with alpine temperatures dropping to -10 C
TUESDAY: Sunny with a few clouds, light northeast wind, freezing level climbing to 1500 m in the afternoon, alpine high temperatures around -3 C.
WEDNESDAY: Clear skies, light north wind, freezing level climbing to 1500 m, alpine high temperatures around -3 C.
THURSDAY: Sunny with a few clouds, light wind, freezing level climbing to 1500 m, alpine high temperatures around -3 C.
Avalanche Summary
Over the weekend a few small (size 1) wind slab avalanches were triggered by riders in northern parts of the region, while small loose wet avalanches were reported around the Coquihalla.
Looking forward, the warming trend poses a number of avalanche concerns including loose wet avalanches, cornice falls, and in northern parts of the region an increasing potential for the deep persistent slab problem to reawaken. The potential for triggering wind slab avalanches also remains possible in steep alpine terrain.
Snowpack Summary
Surface conditions are highly variable with a mix of crusts, moist snow, and hard wind slabs. The surface will become moist on sun-exposed slopes and at lower elevations throughout the day. The warm air coupled with strong radiation from the sun has potential to rapidly weaken the upper snowpack and cornices.
In the alpine, hard wind slabs may be found on all aspects due to variable wind directions. Recent wind has blown from the northeast, forming wind slabs in south to southwest terrain features. In sheltered terrain, about 30 cm of settled snow may overly a melt-freeze crust and potentially small surface hoar crystals.
In the northern part of the region (i.e. Duffey/Hurley/Gold Bridge), a deep instability may linger at the base of the snowpack. It has not produced an avalanche since Feb 17. If one were to trigger the layer, it would likely be in a thin, shallow, rocky spot. A cornice fall could also trigger it. The likelihood of triggering this layer may increase during this warming trend.Â
Terrain and Travel
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
- Carefully evaluate steep lines for wind slabs.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Problems
Loose Wet
Another day of warm weather will destabilize surface snow. The most warming will occur on sun-exposed slopes during the heat of the day, but be suspect of any steep slope that may be heating up, especially if you notice moist snow. Cornices will also weaken with the warming trend.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Triggering wind slab avalanches remains possible after strong northeast wind formed slabs in atypical terrain features last week. These slabs could remain touchy, as they may overly a weak layer of surface hoar.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
In the north of the region (e.g. Duffey, Hurley, Goldbridge), a deep persistent weak layer of faceted grains near the ground presents a lingering concern on steep, shallow slopes in the alpine. The likelihood of triggering this layer may increase over the coming days as the snowpack warms from warm air temperature and sunny skies.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 17th, 2020 4:00PM
