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Avalanche Forecast

Archived

Dec 28th, 2022–Dec 29th, 2022

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

Regions

Coquihalla, Harrison-Fraser, Manning, Skagit.

With limited field observations, forecasters have uncertainty about how storm snow is bonding to old surfaces at higher elevations. Approach this time of uncertainty with skepticism and asses conditions as you travel through the terrain. If you see signs of instability, natural avalanches, whumpfing, and shooting cracks, consider a higher danger rating.

Confidence

Moderate

Avalanche Summary

On Tuesday, a size 1.5 wet slab avalanche was reported at 1450 m.

On Monday, natural wet slab avalanches, up to size 2.5, were observed at 1800 m and below. Slab depths were 40-60 cm.

On Sunday, a size 2.5 natural storm slab avalanche was observed on an east aspect in the alpine.

Please continue to post your observations and photos to the Mountain Information Network.

Snowpack Summary

Since December 30-50 cm of storm snow has accumulated in the alpine. Variable southerly winds have built cohesive slabs in lees. We suspect a thin rain crust exists down 20 within the storm snow. Below 1600 m the snowpack shrank from the heavy rainfall and is now refrozen and very firm.

At higher elevations storm snow covered a layer of facetted and unconsolidated snow that formed during the mid-December cold weather. Snowpack depths reach 140-180 cm at treeline and higher.

Weather Summary

Wednesday Night

Isolated flurries, trace accumulation. Southwesterly wind 20 km/h gusting 30 km/h. Ridgetop low temperature -6 C. Freezing levels 300-500 m.

Thursday

Mostly cloudy with isolated flurries, trace accumulation. Southerly wind 20 km/h gusting 40 km/h. Ridgetop high temperature -1 C. Freezing levels rise from 500m to 1000 m by the end of the day.

Friday

Cloudy with isolated flurries, 5-10 mm. Southerly wind 40 km/h. Ridgetop high temperature -1 C. Freezing levels hover from 700 m to 1000 m.

Saturday

Mostly cloudy with isolated flurries, 2-5 mm. 20-40 km/h southwesterly wind. Ridgetop high temperature -1 C. Freezing levels hover near 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • In times of uncertainty conservative terrain choices are our best defense.
  • Investigate the bond of the recent snow before committing to your line.
  • Be alert to conditions that change with aspect and elevation.

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.