Avalanche Forecast

Issued: Mar 26th, 2017 4:15PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Wind Slabs.

Avalanche Canada mgrist, Avalanche Canada

A persistent slab above a crust will take time to stabilize. Wind slabs are also lurking in the alpine: Evaluate the terrain and snowpack carefully before committing to steeper terrain.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

We're looking at a series of small systems impacting the region throughout the forecast period. The winter weather train keeps rolling into town! MONDAY: Snow in the afternoon (5cm). Strong south wind, freezing level around 1200 m with alpine temperatures around -3 C.TUESDAY: 5-10 cm Monday overnight into Tuesday afternoon, strong southwest wind, freezing levels 1300m.WEDNESDAY: Lingering flurries (5cm possible) moderate south wind, freezing levels 1200m, alpine temperatures around -4 C.

Avalanche Summary

On Saturday, several wind slabs to Size 1.5 were reported on (east) northeast aspects in the north of the region. On Friday, loose snow avalanches were reported at treeline in steep terrain in the south of the region. Reports from Wednesday are limited to several Size 1 loose wet avalanches running on a sun crust at lower elevations. On Tuesday, a skier near Hazelton remotely triggered a Size 1 avalanche that subsequently triggered two other Size 2 avalanches on a persistent weak layer (30 cm deep). The avalanches occurred on northeast aspects at 1400 m.Last Monday, a Size 3 slab avalanche was triggered by a cornice fall on a north aspect at 1700 m north of Kispiox. The cooling weather should help stabilize the persistent slab, but human triggering is still possible in steep or unsupported terrain.

Snowpack Summary

Variable and unsettled weather has given 5-15cm of new snow in the past few days. Winds have been moderate southerly, and sufficient to transport snow in exposed terrain. Recent warming and sun have likely left a crust on solar aspects and below 1300 m (reportedly breakable crust below 1000m). Snow from the past week or so has settled into a 20-60 cm thick slab above an older crust interface. Reports suggest the bond to the crust is poor and has resulted in a reactive slab, in addition to weaknesses down 30-35cm within the storm snow itself (giving sudden planar results in snowpack tests). Weak sugary snow near the ground has been a dormant instability, but it may still be possible to trigger in steep rocky terrain.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A 20-60 cm thick slab above a rain crust has been reactive to human triggers over the past week. Most activity has been in wind-affected terrain. Persistent slabs also have the potential to step down to deep basal weaknesses near the ground.
Choose well supported terrain without convexities.Avoid steep convexities or areas with a thin or variable snowpack.If triggered the persistent slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

An icon showing Wind Slabs
Recent moderate south through west winds have created wind slabs on north through east aspects in the alpine, especially in the north of the region.
Be aware of thin areas that may propogate to deeper instabilites.Be careful with wind loaded pockets. Be aware of wide variation in snowpack depthUse caution in lee areas. Recent wind loading have created wind slabs.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 27th, 2017 2:00PM

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