Archived

Avalanche Forecast

Mar 21st, 2017–Mar 22nd, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

Unsettled spring weather for the next week... Watch for wind slabs sitting above a rain crust and continue to be cautious around slopes with shallow snow.

Confidence

High -

Weather Forecast

WENDESDAY: Flurries starting overnight with 3-8 cm of new snow, moderate south winds, alpine temperatures around -5 C. THURSDAY: Isolated flurries with trace accumulations, moderate southwest winds, alpine temperatures around -7 C.FRIDAY: Cloudy with scattered flurries, moderate south winds, alpine temperatures around -5 C.

Avalanche Summary

On Monday, a size 3 slab avalanche was triggered by a cornice fall on a north aspect at 1700 m north of Kispiox. Over the weekend, several reports describe reactive wind slabs above the March 14 crust, including a size 2.5 snowmobile-triggered avalanche in the Telkwas and a size 2 skier-triggered wind slab north of Kispiox. Additional MIN reports also describe recent natural activity in the size 2-3 range, one of which was triggered by a cornice fall.The recent activity should draw attention to the extent of recent wind transport as well as the March 14 crust's excellent performance as a sliding layer.

Snowpack Summary

Incoming winds and light flurries will transport snow in exposed terrain to form fresh wind slabs. Recent snow continues to settle, with amounts tapering with elevation. At lower elevations, the recent snow sits above a supportive rain crust (March 14). This crust has also been observed at higher elevations in the Telkwa area, and wind slabs have proven especially reactive where they sit above it. At higher elevations, wind has incrementally loaded a weak interface that was buried in late February. The interface is composed of facets, crusts, and surface hoar and may be 40-60 cm deep. There's still some uncertainty around the distribution and reactivity of this interface, but it has been reactive under skier traffic in the north of the region. Weak, sugary snow near the ground continues to be a concern in thin rocky areas.

Avalanche Problems

Wind Slabs

Unsettled weather will build fresh wind slabs in the lee of exposed terrain. Be aware of a rain crust that may be 20-60 cm deep and has recently been a touchy sliding layer.

Be increasingly cautious as you transition into wind affected terrain.Be alert to conditions that change with elevation and aspect.If triggered, wind slabs may step down to deeper layers and result in large avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Deep Persistent Slabs

Even if it isn't making regular appearances, the lingering weakness at the bottom of our snowpack is here to stay. This layer will be most reactive in thin rocky start zones and in shallow snowpack locations.

Avoid steep convexities or areas with a thin, rocky, or variable snowpack.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3