Avalanche Forecast

Archived

Feb 1st, 2024–Feb 2nd, 2024

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.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Coastal, Northwest Inland, Boundary, Stewart, Kispiox, Ningunsaw, Ningunsaw, Ningunsaw.

Continue to make conservative terrain choices as you gather information after a period of rapid change.

Colder temperatures should increase the strength of the snowpack in the short term.

Confidence

Moderate

Avalanche Summary

On Thursday, north of Stewart, a small, natural loose wet avalanche and widespread pinwheeling were reported below treeline. We expect this wet instability to be less likely as temperatures drop overnight into Friday.

On Wednesday, large (size 2.5) natural wind slab avalanches were reported in alpine terrain.

Snowpack Summary

The upper snowpack is a mix of wind slabs, moist snow, dry snow, and a frozen crust that exists up to 1800 m.

Around 60-100 cm below the snow surface, a thick crust buried in early January exists up to 1600 m. At higher elevations, this same layer is weak, sugary faceted snow. More weak layers of facets and feathery surface hoar (formed up until mid-January) sit on top of this layer. The recent storm snow/rain and warm temperatures triggered large avalanches on these layers during the height of the storm. It is expected that they will strengthen as the temperature drops.

Below treeline, the majority of the snowpack is rain-soaked and starting to freeze. It diminishes rapidly to dirt below 500 m.

Weather Summary

Thursday Night

Cloudy. Light rain. 5-15 cm of snow above 1000 m. Moderate south ridgetop wind. Freezing level drops from 1000 m to valley bottom.

Friday

Cloudy, possibly clearing in the afternoon. 5-10 cm of snow expected to valley bottom. Moderate to strong southwest ridgetop wind shifting to west. Freezing level at valley bottom. Treeline low around -11 °C.

Saturday

Mostly sunny. Trace of snow expected. Moderate southwest or west ridgetop wind. Treeline temperature around -11°C. Freezing level at valley bottom.

Sunday

Sunny. Trace of snow expected. Moderate southwest or west ridgetop wind. Treeline temperature around -7 °C. Freezing level at valley bottom.

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.
Make observations and assess conditions continually as you travel.

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.