Avalanche Forecast

Issued: Jan 7th, 2018 5:27PM

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

Avalanche Canada mbender, Avalanche Canada

We are beginning to sound like a broken record, but the load on persistent weak layers continues to build and consolidate. Newly formed storm slabs increase the potential for small avalanches to step down and trigger those deeper persistent layers.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

MONDAY: Flurries, accumulation 5-10cm / Light to moderate southwest wind / Alpine temperature -2 TUESDAY: Flurries, accumulation 5-10cm / Light to moderate southwest wind / Alpine temperature 3 WEDNESDAY: Cloudy with isolated flurries / Light southwest wind / Alpine temperature -8

Avalanche Summary

There is no recent avalanche activity to report, however there have been some serious incidents the past week. Although several days old, the following descriptions are indicative of the current avalanche problem. On Thursday a skier triggered a size 3 avalanche just after entering the east face of Evening Ridge at 2000m near Nelson. The avalanche released to ground and the late November crust was likely involved. The avalanche caught and carried the skier for over 300 m, resulting in significant injuries. Subsequent avalanche control in the area produced 2 additional size 2.5 avalanches. On Monday another avalanche failing on the mid-December interface was triggered remotely from 10 m away as a skier approached a rocky outcropping on an east/southeast facing feature around 1900 m. A skier also triggered a small storm slab on a west facing feature around 2200 m Monday which was suspected to have failed on the late December surface hoar. On New Years Eve a skier was involved on in a size 3 avalanche on an east facing treeline feature at Kootenay Pass. A recent crown profile has shown that this avalanche failed on the late November crust. Click here to see the Mountain Information Network report for this incident.

Snowpack Summary

10-20cm of new snow now sits on a crust on steep southerly aspects and/or on a newly formed layer of surface hoar that was buried January 5th. A series of storms last week produced 25 to 50 cm of low density snow. This means that a surface hoar layer buried late in December is now buried 35-60cm approximately. Dig a bit deeper, you may find yet another surface hoar layer between 60 and 110cm below the surface. This layer was buried buried mid-December and is most pronounced at tree line, but is present below tree line also. The overlying slab is now deep and is gaining cohesion with time and continued warm temperatures, as evidenced by recent avalanche activity listed above.Two laminated crusts created by twin rain events in late November lay just below the mid-December interface, 70 to 110 cm below the surface. Facets may be found sandwiched between the two crusts and have been observed above the uppermost crust too. In shallow rocky terrain the mid-December surface hoar and the late November crust seem to be reacting together which is a volatile combination.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Surface hoar is now buried up to 100 cm deep and has recently produced large human triggered avalanches. This slab appears to be most sensitive at tree line, but it is present below tree line too.
Avoid convexities, steep features and slopes with rocky outcroppings.It's critical to stay disciplined and choose only well supported, low consequence lines.Any steep opening in the trees should be treated as suspect right now

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Storm Slabs

An icon showing Storm Slabs
New snow is slowly accumulating on top of a recently buried layer of weak feathery surface hoar. The snow has been accompanied by south and west winds so expect to see wind slab development in the lee of features at tree line and in the alpine.
Be cautious as you transition into wind affected terrain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 8th, 2018 2:00PM