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Avalanche Forecast

Archived

Feb 9th, 2023–Feb 10th, 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 possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

North Columbia, South Columbia, Esplanade, Jordan, North Selkirk, Shuswap, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, North Okanagan, Retallack, Valhalla, Whatshan.

Continue to make conservative terrain choices and consider the consequences of a chosen slope avalanching. Avoid shallow, rocky snowpack areas where triggering the deep persistent weak layer is still possible.

Be cautious around steep openings within and near treeline elevations as active loading continues.

Confidence

Moderate

Avalanche Summary

With clearer weather on Wednesday, a widespread avalanche cycle from within the storm was observed across the region. Several persistent slab avalanches were reported between 2200 and 2400 meters on all aspects. Notable was a size 2 vehicle remote persistent slab avalanche, triggered from 70 m away on a northwest aspect. Several deep persistent slabs were reported to size 4 throughout the Selkirks and Purcells. Numerous wind slab and storm slab avalanches were reported to size 3 on all aspects at treeline and above.

On Tuesday, a few size 1 skier accidentals storm slab avalanches were reported 20-40 cm deep. Numerous natural avalanches were reported primarily on north and east aspects where storm snow and wind created deep pockets of slab. Explosive control produced numerous storm slab results to size 3.5.

On Monday, A skier accidental avalanche was observed in the Sun Peaks backcountry. The avalanche was a size 2 and is suspected to have run on a weak layer of surface hoar from late January. Several natural storm slab and wind slab avalanches were reported, size 1-2.5, on east and north aspects at treeline and alpine.

Snowpack Summary

Southwest winds have been redistributing storm snow into 20-30 cm soft slabs in exposed alpine and treeline areas. 40-90 cm of storm snow from the week sits above wind-affected surfaces and a crust that extends up to 1800 m in the northern part of the region and up to 2000 m further south. Small facets may be found above the crust.

Deeper in the snowpack two layers of surface hoar which formed in early January are 60 to 120 cm deep. These weak layers are still on our radar, although snowpack tests are indicating they may be strengthening.

Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region.

Weather Summary

Thursday Night

Partly cloudy clear periods and isolated flurries, trace accumulation. Southwesterly ridge wind 40-60 km/h. Alpine temperature low of -5 °C. Freezing level 500 m.

Friday

Cloudy with sunny periods and isolated flurries, 3-7 cm accumulation. Southwesterly ridge wind 40 km/h easing to 20 km/h in the afternoon. Alpine temperature high of -3 °C. Freezing level 1200 m.

Saturday

Cloudy with sunny periods and isolated flurries, trace accumulation. Westerley ridge wind 20 km/h. Alpine temperature high of -4 °C. Freezing level 1000 m.

Sunday

Cloudy with isolated flurries, 5-10 cm accumulation. Southwesterly ridge wind 40 km/h in the afternoon. Alpine temperature high of -2 °C. Freezing level 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.
  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

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.

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.