Avalanche Forecast

Issued: Feb 5th, 2017 4:28PM

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

Avalanche Canada cgarritty, Avalanche Canada

Wind slabs have been either resupplied or thinly covered, depending on local winds. Our persistent slab problems remain slow to heal.

Summary

Confidence

Moderate -

Weather Forecast

Monday: Cloudy with sunny periods and isolated flurries bringing a trace of new snow. Winds light from the northeast. Alpine temperatures of -23.Tuesday: A mix of sun and cloud. Winds light from the east. Alpine temperatures of -17.Wednesday: A mix of sun and cloud. Winds light from the southeast. Alpine temperatures of -15.

Avalanche Summary

Recent reports include details of a remote triggered size 2.5 avalanche that occurred in the south of the region on Thursday. The slide took place on a roughly 30 degree south-facing slope at 2100 m in elevation. The remote trigger, a depth of 80 cm, and a failure plane attributed to our January 15 surface hoar all reinforce enduring concerns for persistent slab problems in the region. On Monday, several natural wind slab and storm slab avalanches up to size 2.5 were reported. These slabs were typically 30-50 cm thick and failed on a variety of aspects at treeline and in the alpine. Fresh wind slabs have since been (and may remain) sensitive to light triggers, especially on steep and unsupported (convex) slopes.Persistent slab avalanches remain a serious concern for the region. Late January saw people triggering numerous large avalanches, several of which resulted in multiple burials. These avalanches all released on, or stepped down to, the mid-December persistent weakness down 1-1.5 m in the snowpack. Check out this list of recent near misses which includes many in the Cariboo region.

Snowpack Summary

Light snowfall over the past few days (mainly in the south of the region) has given a thin cover to wind slabs that currently exist on a variety of aspects in wind-exposed terrain. In more sheltered areas, the new snow has also begun burying both faceted surface snow as well as surface hoar that exists on sheltered open slopes. The persistent weakness buried mid-January is now down 50-100 cm and consists of buried surface hoar in sheltered areas, and/or widespread faceted old snow. It has generally stabilized but may remain sensitive to human triggers in isolated areas, especially where buried surface hoar is preserved. Another surface hoar/facet weakness was buried mid-December and can now be found down 70 cm in shallow snowpack areas, or as much as 1.5 m in deeper snowpack areas. It woke up during the last storm and has remained reactive to human triggers. This weak layer is responsible for several large human-triggered avalanches, including some with multiple burials, and the layer may remain reactive for the foreseeable future. Click here for a new blog post with more details.

Problems

Wind Slabs

An icon showing Wind Slabs
Variable winds have formed wind slabs on a wide range of aspects over the past week. Light snowfall and gusty winds over the past couple of days have contributed to the problem, especially in the south of the region.
Avoid areas where the surface snow feels stiff or slabby.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered in thin areas, wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
The persistent weakness buried mid-December has been responsible for several large human-triggered slab avalanches and subsequent burials in late January. These deeper weaknesses will be slow to heal and must be considered in your terrain selection.
Avoid shallow snowpack areas where triggering is more likely.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Feb 6th, 2017 2:00PM

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