Avalanche Forecast

Archived

Jan 5th, 2023–Jan 6th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Glacier.

We have an unusually weak and faceted snowpack at Rogers Pass.

Sticking to lower angled, supported slopes, and avoiding shallow rocky areas, will reduce your chances of triggering the deeper persistent weak layers.

Confidence

Moderate

Avalanche Summary

The steep terrain of the Macdonald gullies continue to spit out large natural avalanches daily. Notably, gully #6 produced a size 3 slab avalanches during a brief wind spike Thursday Morning.

There was a skier triggered slab avalanche on Avalanche Crest on Wednesday.

On Monday a size 2 avalanche was remotely triggered from a shallow snowpack area on Bruins Ridge. These types of spooky avalanches continue to be reported in nearby areas, and are causing anxiety amongst avalanche forecasters! Stay away from thin, rocky areas, and ensure no other skiers are below you before entering your line.

Snowpack Summary

The top 30cm of snow is low-density and provides great powder turns. Steeper SW and W aspects have a thin sun crust on the surface. Brief moderate Northerly winds on Friday may have created some wind effect in exposed areas at upper elevations.

The December 23rd facet interface, down ~70cm, is gaining strength, but remains a concern in shallow snowpack areas.

The November 17th facet/crust/surface hoar layer is still active in snowpack tests, exhibiting 'sudden collapse' or 'sudden planar' results, and producing isolated large avalanches in neighboring areas.

Weather Summary

Low pressure off the coast is trying to push some weather our way - but only barely succeeding. Sporadic light flurries could give us 5-10cm of accumulated snowfall by Sunday.

Tonight: Isolated flurries, Alpine Low -6*C. Light/gusty SW ridgetop wind.

Friday: Cloudy with isolated flurries. High -6*C. Light SW winds.

Saturday: Scattered flurries (5cm). Low -8*C, High -4*C. Light SW winds.

Sunday: Isolated flurries. Low -10*C, High -6*C. Light/gusty South wind.

Terrain and Travel Advice

Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

Problems

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.