Avalanche Forecast

Issued: Jan 24th, 2017 4:02PM

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

triley, Avalanche Canada

Northwest Inland.

The deep persistent slab problem is more likely in shallow snowpack areas that have developed a slab over basal facets.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Overcast with a chance of flurries and moderate southwest winds overnight and freezing at valley bottoms. Overcast with a couple of cm on Wednesday combined with moderate-strong southwest winds and freezing at valley bottoms. Strong southwest winds combined with 3-5 cm of new snow on Thursday as the freezing level rises to about 1000 metres. Strong southwest winds combined with 5-10 cm of new snow on Friday with freezing levels climbing up to about 1500 metres; uncertainty with the forecast for Friday, this may be limited to the north and west of the region.

Avalanche Summary

A few large avalanches up to size 3.0 were remotely triggered in the Kispiox area on Monday on south thru west aspects at 1700-1800 metres. These avalanches were about 80 cm deep and are suspected to have released on the December 25th surface hoar.

Snowpack Summary

5-20 cm of settled storm snow sits above a widespread rain crust up to about 1300 m. Recent winds have likely formed wind slabs on lee and cross loaded features. Several buried surface hoar layers have been reported 40-80 cm deep and have given variable results in snowpack tests. Many areas have hard slabs in the upper snowpack above weak sugary snow near the ground. Triggering a deep persistent slab above this sugary snow will remain a low probability high consequence scenario for some time.

Problems

Deep Persistent Slabs

Weak sugary snow exists at the bottom of the snowpack, creating the potential for full depth avalanches. This problem may be more likely in shallow snowpack areas near Kispiox and in the north of the region.

Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.Assess start zones carefully and use safe travel techniques.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Wind Slabs

Wind slabs are likely lingering at higher elevations. If triggered, they have the potential to 'step down' and trigger large deep persistent slab avalanches.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 25th, 2017 2:00PM