Avalanche Forecast
Issued: Apr 16th, 2021 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Cornices and Deep Persistent Slabs.
jcoulter,
Avalanche Canada
No overnight freeze combined with 3000m freezing levels means less window for safe travel, even early in the morning. Steer clear of steep slopes when they are moist or wet and give cornices a wide birth. Check out the Forecaster's Blog for information on spring conditions.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
FRIDAY NIGHT: Clear / light, southwest ridgetop wind / alpine high temperature +3 / Freezing level 3000 m.
SATURDAY: Sunny / light, northwest ridgetop wind / alpine high temperature +8 / Freezing level 3000 m.
SUNDAY: Partly cloudy, clearing in the afternoon / strong east ridgetop wind / alpine high temperature 0 / freezing level 1700 m.
MONDAY: Sunny / moderate easing to light southeast wind / alpine high +7 / freezing level 2400 m.
Avalanche Summary
We don't have a lot of information coming in for this region, but there have been reports of wet loose avalanches on south-facing slopes at all elevations and a few size 2-2.5 cornice failures on north and east facing slopes.Â
The lower snowpack has been strong and settled over the past month, however, the dramatic warming this week could potentially wake up weak facets at the bottom of the snowpack. This is particularly a concern on steep, rocky slopes with a shallow or thin to thick snowpack. Cornice failures or a rider hitting a thin spot in the snowpack are the most likely ways to trigger these weak layers.
Snowpack Summary
Lingering wind slabs may still be reactive in isolated locations on steep northerly aspects in the alpine that still have dry snow. All other terrain has been undergoing a melt-freeze cycle with successive days of warm sunny weather. Things will be "more melt, less freeze" on Saturday as we do not expect a good overnight recovery.Â
Strong solar radiation and warming will trigger more wet loose avalanches on Saturday as the snow loses cohesion. Cornices are large and fragile. Cornice falls could trigger large avalanches on the slopes below.
The snowpack is overall strong and settled in most areas, however, sustained warming can increase the likelihood of large avalanches failing on deeply buried weak layers.This is most likely to occur on steep, rocky alpine slopes with a shallow or thin to thick snowpack.
Terrain and Travel
- Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
- Extra caution is needed around cornices under the current conditions.
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Problems
Loose Wet
With multiple nights of no overnight refreeze, expect natural and human triggered wet loose avalanches on a variety of aspects and elevations. Danger will be greatest on steep sun exposed slopes.
The more the snowpack warms-up and weakens, the more conservative you'll want to be with your terrain selection. Wet loose avalanches can entrain a lot of snow and cross elevation bands.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Strong solar radiation and warming will likely trigger the large cornices that hang over ridge lines. Cornice falls are a hazard on their own, but could also trigger large avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
Prolonged warming could increase the sensitivity of deeply buried layers in the snowpack. While these layers have not been reactive lately, you should practice increasing caution during this period of warm weather. Steep rocky terrain with a shallow or thin to thick snowpack are most suspect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 17th, 2021 3:00PM
