Avalanche Forecast
Issued: Feb 25th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
kdevine,
Avalanche Canada
New snow and wind will mean that storm slabs are to be expected, and will likely be reactive to human triggering in many areas.
The potential exists to trigger deeper weak layers, resulting in large avalanches. Choose conservative terrain.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Forecast snowfall amounts are uncertain.
Weather Forecast
THURSDAY NIGHT - Flurries, 5-15 cm / moderate to strong southwest wind / alpine low temperature near -10Â
FRIDAY - Mainy cloudy with flurries, 5 cm / moderate northwest wind / alpine high temperature near -8
SATURDAY - A mix of sun and cloud with a few flurries / moderate west wind / alpine high temperature near -13
SUNDAY - Mainly cloudy with scattered flurries, 5 cm / strong southwest wind / alpine high temperature near -5 / freezing level 1500 m
Avalanche Summary
On Wednesday there were two size 3 persistent slab avalanches reported on east to southeast aspects around treeline. These were notable as they failed on the late January persistent weak layer.Â
The Selkirks were the hotspot for avalanche activity over the weekend and into Monday, with widespread size 2-3 natural storm slab avalanches and size 3-4 explosives-triggered avalanches.
Reports from the Monashees indicate a natural avalanche cycle up to size 2.5 over the weekend. Explosives work on Tuesday in the northern Monashees produced limited results including a few size 1, and one size 2 cornice triggered storm slab.
Snowpack Summary
5-15 cm is expected overnight on Thursday with another 5 cm on Friday. This will add to the 60-100 cm of recent storm snow. Deep wind deposits may be found in lee terrain features in the alpine and open treeline areas, and will likely remain reactive to human triggers. All of this new snow sits over weak, faceted snow from the recent cold snap.Â
There is now 70-120 cm of snow above the late January persistent weak layer which is composed of surface hoar in sheltered areas in the trees and/ or a crust on steep solar aspects.Â
Terrain and Travel
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Be carefull around freshly wind loaded features.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
Problems
Storm Slabs
Fresh snow combined with moderate to strong winds will likely continue to form fresh and reactive storm slabs, especially in wind-loaded areas. A change in wind direction on Friday may mean wind loading can be found on all aspects.
Cornices are experiencing rapid growth with strong west to southwest winds, use caution on ridgelines, and in terrain with cornices above.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
There are several persistent weak layers in the snowpack. The most recent is down 40-80 cm and was formed during the recent cold snap.
The late January persistent weak layer is down 70-120 cm. Though avalanches on this layer have been sporadic, they have been large.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 26th, 2021 4:00PM
