Avalanche Forecast
Issued: Nov 19th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Deep Persistent Slabs and Loose Dry.
Stephen Holeczi,
New snow, wind, and a weak layer of crust and facets are making the snowpack more complex. Time to dial back terrain choices. Good ski conditions in sheltered areas that are deep enough to cover the rocks! SH
Summary
Weather Forecast
5-10cm expected on Friday, with increasing winds at upper elevations to strong from the S/SW. Temperatures -10 in the valley warming to -5C, and -12 to -15C in the alpine.
Snowpack Summary
15-30 cm snow over the last few days with new and buried windslabs existing in alpine and treeline. The Nov. 5 Facets/crust combo is 20-40 cm off the ground and is buried 40-70cm producing variable test results. It extends up to 2400m on shady aspects and higher on solar aspects. Total snow depths at treeline are 50-100 cm.
Avalanche Summary
Avalanche control on 93S yesterday produced a few slides up to size 2. Lake Louise ski patrol were able to trigger a size 2 wind slab in N facing terrain that hadn't had previous control. Skier remote report sz 1.5 today on facets to ground (40cm deep) at 2000m, 80m wide near Watermelon peak. Other audible avalanches heard but poor visibility.
Confidence
Due to the number and quality of field observations
Problems
Wind Slabs
Wind slabs are forming at treeline and alpine elevations from recent storm snow and increased winds. Whumpfing noted Thursday and ski hills reporting explosive triggered slabs. Expect these to continue growing with increased winds Friday.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The Nov.5 crust/ facet layer exists up to 2500m on shady aspects, and higher on solar aspects. Where there is a dense slab overlying this layer, it is starting to become reactive to skier traffic. This will be a layer of concern for a long time.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
Up to 30cm over the past few days which will be prone to sluffing in steep terrain, especially for climbers and steep gully skiers. This will be less of a problem in areas that don't receive as much snow.
- Use caution above cliffs where small avalanches may have severe consequences.
- Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Nov 20th, 2020 4:00PM
