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Avalanche Forecast

Archived

Dec 29th, 2022–Dec 30th, 2022

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

Regions

Glacier.

The recent storm snow is making for good quality skiing throughout the park.

Keep a watch out for whumpfing, hollow sounds and shooting cracks that would indicate the snowpack is weak and possible to rider triggering.

Confidence

Moderate

Avalanche Summary

On Thursday we observed two natural avalanches, size 2-2.5 along the highway corridor from steep terrain on N and SE asp.

Skiers were triggering avalanches in neighboring operations just outside the park on Wednesday, these accidentally triggered avalanches were up to size 3.0 in size, and primarily failing at the storm snow/facet interface.

Artillery control on Xmas and Boxing Day had good results, with many avalanches observed in the sz 2.5-3.5 range. There was evidence of step-down avalanches on the persistent weak layers.

Snowpack Summary

Recently built storm slabs, 55-65cm deep, sit on top of a weak and faceted snowpack. This interface will likely persistent as a weak layer for awhile.

Nov 17 SH down 100-120 cm, while still obvious in the snowpack, has mostly been unreactive in stability tests over the past three days. The Dec 05 and Dec 17th SH have been unreactive in tests since the storm.

Weather Summary

A weakening front affecting the Coast will give unsettled weather into the weekend.

Friday: Flurries, up to 5cm of snow. Alpine low -10*C, high -5*C, 1300m freezing level (FZL). Light SW ridgetop wind.

Sat: Flurries, up to 10cm snow. Alpine low -9*C, High -7*C, 1200m FZL. Light SW wind.

Sun: Clearing. Alpine low -13*C, High -9*C. Light W wind.

Terrain and Travel Advice

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Exercise caution on steep, unsupported slopes.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.