Avalanche Forecast
Issued: Feb 4th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Storm Slabs.
swerner,
Avalanche Canada
Strong winds from the northwest will likely redistribute recent storm snow to leeward slopes building reactive wind slabs. Natural avalanche activity may taper on Friday but skier and rider triggering is likely.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations. Forecast snowfall amounts are uncertain.
Weather Forecast
Friday: A mix of sun, cloud, and flurries accompanied by a strong northwest wind. Alpine temperatures near -10 and freezing levels in the valley bottom.
Saturday: Snow 5-10 cm. Moderate westerly wind. Alpine temperatures low at -23 and a high of -10.
Sunday: Snow 5-10 cm. Ridgetop wind switching to the East and blowing in the light values. Alpine temperatures low of -30 and high of -20.
Avalanche Summary
No recent reports on Thursday. On Wednesday, numerous loose-dry natural avalanches were reported up to size 1.Â
With forecast strong wind, fresh wind slabs, and recent storm slabs will likely remain reactive Friday. Loose-dry avalanches may occur from steep terrain features.
Snowpack Summary
Up to 35 cm of new snow fell by Thursday morning. The new snow accompanied by a strong west-northwest wind will likely redistribute some of this snow to leeward slopes and terrain features building fresh storm and wind slabs. A surface crust may exist at lower elevations. This additional snow brings up to 60 cm of storm snow (over the past week) that sits above a plethora of old snow surfaces. In the alpine and at treeline the buried surfaces consist of stiff wind affected snow, surface facets, sastrugi, pockets of soft snow, surface hoar in isolated areas sheltered by the wind, and a sun crust on steep solar aspects. Below 1900 m a thick crust can be found underneath the recent snow.Â
A solid mid-pack sits above deeply buried decomposing crust and facet layers near the bottom of the snowpack (80-150 cm deep). Though unreactive under the current conditions, steep rocky slopes and shallow snowpacks should still be carefully assessed and approached with caution.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Avoid terrain traps where the consequence of any avalanche could be serious.
- Be carefull with sluffing in steep terrain, especially above cliffs and terrain traps.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Moderate to strong northwest wind will continue to redistribute the new snow building wind slabs in lee terrain features in the alpine and at exposed treeline. They may have a poor bond with old snow surfaces, for example, hard wind affected layers and pockets of surface hoar or surface facets. If the bond is poor, the wind slabs will be more reactive.
Looming cornices may be large and fragile. With respect, give them a wide berth from above and below.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Up to 30 cm of new snow fell by Wednesday morning. Storm slabs may continue to be reactive on Friday, especially in localized areas that received higher snowfall amounts.
Loose dry avalanches may occur from steep terrain features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 5th, 2021 4:00PM
