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Avalanche Forecast

Archived

Jan 3rd, 2023–Jan 4th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Glacier.

Natural avalanche activity has slowed, but with no new snow to refresh the slopes, folks are pushing into untouched terrain to get their own "fresh tracks".

Be very wary of moving into thinner snowpack areas, where the likelihood of triggering the deeper persistent layers is much higher. The resulting avalanches would be large, destructive, and hard to avoid.

Choose conservative, supported terrain to get to the great skiing in the Pass.

Confidence

Moderate

Avalanche Summary

On Monday a size 2 avalanche was observed off of the popular Bruins Ridge into 8812 Bowl. It was likely remotely triggered by a skier, 40-50cm deep, 60m wide and ran 200m, covering tracks down into the bowl.

On Sunday several size 2-2.5 natural storm slab avalanches were observed from steep, wind-loaded terrain, and several size 1-1.5 dry loose avalanches from steep and rocky solar aspects.

Snowpack Summary

The top 30cm of snow is low-density and provides great powder turns. The Dec 23 facet interface is down ~70cm but is rounding and gaining strength. The Dec 5 and Nov 17 surface hoar layers have been less reactive recently but had been exhibiting 'sudden' results in snowpack tests.

Weather Summary

Dry conditions reign supreme in Rogers Pass, with a high pressure ridge keeping all weather systems at bay.

Wed: sun and clouds, Alp high -8*C, light S winds

Thurs: sun and clouds, Alp high -1*C, light S winds

Fri: mix of sun/cloud with isolated flurries, trace snowfall, Alp high -3*C, light/gusty SW winds

Terrain and Travel Advice

  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Use small low consequence slopes to test the bond of the new snow.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

Problems

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.

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.