Avalanche Forecast
Issued: Feb 26th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
swerner,
Avalanche Canada
Reactive wind slabs will be the primary concern on Saturday. The natural avalanche cycle may have tapered off, however; slopes may continue to be primed and waiting for skier and rider triggering.
Summary
Confidence
Weather Forecast
Yet another approaching Pacific warm front will unleash Saturday through Monday. This will bring strong to extreme wind, rising freezing levels, and some fresh snow.
Saturday: Flurries in the afternoon. Ridgetop wind strong from the southwest and alpine temperatures near -2. Freezing levels rising 900 m.
Sunday: Snow 5-20 cm. Ridgetop wind extreme. Freezing levels 1000-1200 m.
Monday: Mix of sun and cloud with some flurries. Ridgetop wind moderate from the southwest and alpine temperatures near -5. Freezing levels valley bottom.
Avalanche Summary
On Friday, fresh natural reactive wind slabs up to size 2 were reported from the alpine on E-NE aspects.
On Thursday, numerous audible avalanches were reported in the southwestern part of the region, and an ongoing avalanche cycle was noted. This area received heavier snowfall amounts up to 30 cm so a lot of variability across the region. Sluffing of the new snow occurred in steep terrain features.
For the weekend, I suspect wind slabs to be the primary concern, however; in parts of the region that receive more than 20 cm of fresh snow, storm slabs may also be a factor. Natural avalanche activity may taper but skier and rider triggering is likely.
Snowpack Summary
20-30 cm of new snow fell Thursday. This arrived with strong to extreme southwest to northwest wind building fresh and reactive wind slabs and storm slabs on wind-sheltered slopes.
This brings 40 to 60 cm of snow which overlies a variety of old snow surfaces consisting of hard wind-affected snow in exposed terrain and weak, faceted snow or surface hoar crystals in sheltered terrain, suggesting it may take some time for the snow to bond to these surfaces.
Basal faceted snow remains part of the snowpack structure in much of the region. Once we see a substantial warm-up, we'll be thinking about the potential for the reactivation of basal layers.
Terrain and Travel
- Choose conservative terrain and watch for clues of instability.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Cranking southwest wind and new snow have formed fresh new wind slabs. Changing winds from the northwest on Friday will add to the complex loading pattern. Wind slabs may be found on most aspects at upper elevations and may be more reactive where they overlie weak surfaces formed mid-February, potentially including weak surface hoar and/or faceted grains.
Large looming cornices exist. Be diligent and give them a wide berth from above and below. Cornices may fail due to extreme wind and warming tempertures on Sunday.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 27th, 2021 4:00PM
