Avalanche Forecast
Issued: Feb 3rd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
William Lawson,
Parks Canada
Though natural avalanche activity has tapered, the potential to trigger very large avalanches still exists.
Travel cautiously in areas with overhead hazard, forecasted winds could initiate another avalanche cycle.
Summary
Weather Forecast
Increased cloud cover will begin Tuesday afternoon as another small system brings precipe to the region. Forecasted snow amounts vary between 5cm to 15cm by end of day Wednesday. A gradual increase in winds will start Monday night with peak values of 70km/h by mid day Tuesday.
Snowpack Summary
30 to 70 cm of recent storm snow at higher elevations, with a rain crust up to 1800m. Wind slabs exist in the alpine and exposed areas at tree line. The Dec 31 layer of facets, surface hoar and sun crust is currently down 50-100cm. The deep persistent basal layer sits 20 to 40cm above the ground and is more developed in shallow snowpack areas.
Avalanche Summary
No new natural avalanche activity was observed Monday, though evidence of a widespread natural cycle is still visible throughout the region. Explosive control in Yoho produce numerous results to size 2.5, triggering mostly storm snow. The snowpack appeared to be less reactive Monday compared to the avalanche control done over the weekend.
Confidence
Problems
Wind Slabs
Wind slabs developed rapidly along with fragile cornice growth from consistently strong Southwest winds. Despite the cooling trend, expect these slabs to remain sensitive to failure over the short term.
- 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
Persistent Slabs
This layer of surface hoar, facets and crusts is down 50 to 100cm and produces sudden pop/drop results in snowpack tests.
- Dig down to find and test weak layers before committing to a line.
Aspects: All aspects.
Elevations: Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
With start zones loaded, avalanches can easily scrub to ground and entrain mass as they move through the track and into the run out zone.
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 4th, 2020 4:00PM
