Avalanche Forecast

Archived

Apr 22nd, 2023–Apr 23rd, 2023

Alpine

Natural avalanches possible, human triggered probable.

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Kitimat, Seven Sisters, Howson.

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

Concern for triggering large persistent slab avalanches remains. Avoid steep, rocky, and wind affected areas where triggering slabs is more likely.

Confidence

Low

Avalanche Summary

No avalanches were reported on Friday. However, observations in this region are currently very limited.

A few naturally triggered size 2 wind slab avalanches were reported on steep, northerly aspects in the alpine on Thursday.

Most professional operations are now closed which means we have very little snowpack or avalanche observation data. Please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.

Snowpack Summary

New snow and strong southerly wind may have formed wind slabs on lee aspects at treeline and above.

A crust exists up to ridgetop on south-facing slopes and on all aspects up to approximately 1300 m.

A weak layer buried in late March is down 40-60 cm and exists as surface hoar and facets on north-facing slopes and a crust elsewhere.

The mid and lower snowpack is considered generally strong and well-bonded.

Weather Summary

Saturday Night

Cloudy with flurries; 3-20 cm (rain below 900 m) / 40 km/h south ridgetop wind / Temperature at treeline around -2 C / Freezing level 1000 m

Sunday

Cloudy with isolated flurries; 0-10 cm (rain below 1000 m) / 40 km/h south ridgetop wind / Temperature at treeline around -1 C / Freezing level 1200 m

Monday

Cloudy with isolated flurries; 3-5 cm / 50 km/h southwest ridgetop wind / Temperature at treeline around -2 C / Freezing level 1100 m

Tuesday

Cloudy with isolated flurries; 0-3 cm / 40 km/h southwest ridgetop wind / Temperature at treeline around -3 C / Freezing level 1000 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

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.

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.