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Avalanche Forecast

Archived

Dec 31st, 2022–Jan 1st, 2023

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

Regions

Glacier.

More new snow is making for good quality snow sliding throughout the park.

Several weak interfaces buried within the snowpack are becoming less likely to trigger, but still have the potential to produce very large avalanches. Avoid being drawn in to bigger terrain by the good conditions and lack of obvious signs of instability.

Have a happy new year!

Confidence

Moderate

Avalanche Summary

On Saturday, we observed a few natural avalanches up to size 2.5 from steep terrain in the highway corridor. These were starting as loose dry avalanches from steep unskiable terrain, with some triggering storm slabs on planar slopes below.

On Friday, a field team on Avalanche Crest triggered a small (size 1.5) storm slab near the ridge crest. We also observed two large natural avalanches in the highway corridor, from the steep North facing MacDonald gullies.

Helicopter bombing at several operations near the park boundary has produced large avalanches recently (up to size 3.0). Many of these were failing at the storm snow/facet interface which was buried on December 23rd.

Snowpack Summary

20-30cm of low density new snow has created a loose dry avalanche problem, as well as adding to the load on recently built storm slabs up to 70 cm deep.

The Dec. 23rd interface, between last weeks storm snow and the previously weak and facetted snowpack, is strengthening but has been the failure plane for large human triggered avalanches in neighboring areas recently.

The mid-snowpack Dec 05 and Dec 17th surface hoar layers have been unreactive in snowpack tests since last weeks storm.

The Nov 17 surface hoar persists down 80-110 cm, can still be easily found in the snowpack around treeline, and continues to give sudden results in snowpack tests.

Weather Summary

A building ridge of high pressure will give a clearing trend into next week.

Tonight: Isolated fluries. Alpine Low -9*C. Light SW ridgetop wind.

Sunday: Clearing through the day. Alpine High -9*C. Light West wind.

Monday: Mostly Sunny. Low -8*C, High -3*C. Light South wind.

Tuesday: Mostly Sunny. Low -12*C, High -4*C. Light SW wind.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Avoid convexities, steep unsupported terrain and rocky outcroppings.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.