Avalanche Forecast
Issued: Dec 19th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Dry and Deep Persistent Slabs.
Benjamin Firth,
A series of storms will enter the region over the next few days. The more snow and wind we receive the higher the avalanche danger. Avalanche control forecasted on 93N between Sunday morning and Tuesday afternoon. Check 511 for up to date information
Summary
Weather Forecast
Saturday night: Up to 25cm of new snow with continued moderate SW winds
Sunday: Periods of snow. Accumulation: 16 cm. Alp tmp: Low -9 C, High -3 C. Mostly light ridge wind occasionally gusting to 40 km/h. Freezing level: 1700 metres.
Mon and Tues: Accumulation: Up to 30cm.
Snowpack Summary
Up to 30cm of storm snow over last few days. SW winds continue to build wind slabs in the alpine and open treeline. Surface hoar down ~35cm in sheltered locations treeline and below. The midpack is generally supportive with a weaker base consisting of facets and some locations depth hoar. Avg depth is 65cm - 160cm depending on region and elevation.
Avalanche Summary
Road patrol south today no new avalanches observed. One recent wind slab size 2.5 avalanche was observed Friday that was out of a East facing alpine feature in the Mount Wilson area otherwise nothing else was observed. Over the last four days compression tests in the ice fields treeline and below produced no results.
Confidence
Intensity of incoming weather systems is uncertain on Saturday
Problems
Wind Slabs
New snow and moderate to strong winds forming wind slabs on leeward and cross-loaded terrain features.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Minimize overhead exposure during periods of heavy loading from new snow, wind.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
New snow may be reactive on the Dec 14th layer
- Carefully assess open slopes at and below treeline where buried surface hoar may be preserved.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Be cautious of thick to thin snowpack areas being likely trigger locations. The new windslabs forming have the potential to step down to the weakness at the base of the snowpack.
- Use caution in thin snowpack areas.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 20th, 2020 4:00PM
