Avalanche Forecast

Archived

Jan 24th, 2023–Jan 25th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

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.

Regions

Northwest Coastal, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson, Ningunsaw.

Seek conservative terrain choices that avoid avalanche terrain during this period of high hazard.

New snow and a buried weak layer combined have the potential to produce very large avalanches.

Confidence

Moderate

Avalanche Summary

Monday: A widespread natural avalanche cycle occurred during yesterday's storm event. A variety of avalanche sizes were observed from small (size 1) to very large (size 3). Even during limited visibility, the extent of the activity was notably high.

Sunday: A relatively quiet day for avalanche observations and reporting. Explosive control produced limited small (size 1 to 1.5) results.

Saturday: Numerous large (size 2) wind slab and storm slab avalanches have been reported. These avalanches were located on north aspect terrain between the elevation bands of 1400 to 1600 m. A few of them were naturally initiated with most being either explosive or ski-cut triggered.

Friday: Another round of ongoing avalanche occurrences has been reported, as visibility has been limited these reports suggest that many more have been occurring. Numerous both natural and explosive triggered large (size 2-2.5) have been reported. These avalanches have all initiated within the 1500 - 1600 m range just below ridgetop features. One very large (size 3) avalanche ran 1000 m in length and the common theme of running far and fast due to firm surface conditions has been a common theme. A rain-on-snow event triggered loose wet avalanches 1300 m and below.

Riders should exercise restraint and patience as the new and past storm instability requires time to settle and bond. Choose simple non-avalanche terrain that is low-angle and well-supported. Avoid steep and wind-loaded areas at upper elevations. Keep in mind the potential for deeper instabilities to produce large and surprising avalanches that will run far and fast.

Snowpack Summary

Past storm snow amounts between 30 to 40 cm and has been redistributed by strong to extreme south wind. Expect at upper elevations, these southerly winds have scoured windward areas and redistributed this storm snow into wind slabs in lee areas. New storm snow now overlies the past 50 to 70 cm. Below 1000 m moist snow or a crust can be found at or near the surface.

A weak layer of surface hoar buried in early January is now down 30-60 cm. This layer is spotty in its distribution and is of greatest concern in sheltered and shaded openings at treeline.

Weak layers that were reactive over the Christmas and New Year's period have shown signs of bonding and gaining strength. These include a surface hoar layer buried on Dec 28 found 50 to 100 cm deep and a facet layer buried on Dec 23 found 70 to 120 cm deep.

Weather Summary

Tuesday night

Cloudy with light snowfall, 1 to 5 cm of accumulation. Alpine temperatures are 1 °C. Ridge wind west 40 km/h. The freezing level rises to 1500 m.

Wednesday

Cloudy with rain and snowfall, 5 cm of accumulation. Alpine temperatures 2 °C. Ridge wind southwest 50 km/h. Freezing level 1800 m.

Thursday

Cloudy with very light rain and snowfall, trace amounts of accumulation. Alpine temperatures 1 °C. Ridge wind west 50 km/h. The freezing level of 1800 m descends to 1000 m.

Friday

Cloudy with very light rain and snowfall, trace amounts of accumulation. Alpine temperatures -2 °C. Ridge wind northwest 50 km/h. The freezing level 500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Minimize your exposure time below cornices.
Extra caution for areas experiencing rapidly warming temperatures for the first time.

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 Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.