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Avalanche Forecast

Archived

Dec 20th, 2022–Dec 21st, 2022

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

Regions

Glacier.

OH! OH! OH! It is frigid! Short days and brutally cold temps encourage returning to the parking lot with plenty of daylight.

Bring many warm layers and have a conservative mindset if you head into the backcountry. Small mishaps can become serious emergencies in these conditions.

Confidence

Moderate

Avalanche Summary

Settlements and whumpfing continue to be reported in previously untracked terrain.

Isolated natural sluffs and small avalanches up to size 1 were observed out of steep solar terrain on Monday.

Adjacent to Rogers Pass in less-traveled terrain, extensive whumpfing and cracking is prevalent at Tree-line elevations.

Snowpack Summary

Up to 10cm now buries the Dec 16 surface hoar (up to 10mm at tree line and below) and a crust on solar aspects.

The snowpack is thin (~110cm at 2000m) and generally facetted. The Dec 5 and Nov 17 surface hoar layers are down ~40cm and ~70cm respectively and have produced sudden results in snowpack tests.

Weather Summary

The cold continues, with a warm respite arriving on the weekend along with snow.

Wed will see the coldest temps (-30*C), with gradually warming Thurs and a marked increase on Fri (-9*C!!). Winds remain light at ridgetop, while strongly stripping away any exposed skin in the valley bottoms.

Terrain and Travel Advice

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Exercise caution on steep, unsupported slopes.
  • Uncertainty is best managed through conservative terrain choices at this time.

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.