Avalanche Forecast

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.

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.

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.

• 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.