Avalanche Forecast

Issued: Jan 28th, 2019 4:42PM

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

ghelgeson, Avalanche Canada

Cariboos.

Manage wind slabs by paying attention to how the snow feels underneath your skis/track, and backing off where it feels stiff. Increase your caution at and below treeline, buried surface hoar is well preserved, especially between 1500 & 1800 m.

Summary

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

High pressure, cold temperatures and clear skies should allow for great travel and visibility Tuesday. Storm clouds build back in Wednesday opening the door to snowfall that should continue through the weekend. MONDAY NIGHT: Freezing level at valley bottom, light northerly wind, no precipitation expected.TUESDAY: Clear skies, freezing level at valley bottom, light variable wind, no precipitation expected.WEDNESDAY: Overcast, freezing level at valley bottom, mostly light variable wind with strong northwest wind at ridgetop, 1 to 5 cm of snow possible.THURSDAY: Overcast, freezing level at valley bottom, light to moderate west/southwest wind, 1 to 5 cm of snow possible.

Avalanche Summary

On Sunday cornice failures to size 1.5 were observed on north through east facing terrain around 2000 m. Small natural wind slab avalanches to size 1 were reported on east and northeast facing terrain between 2000 and 2300 m.On Saturday a skier triggered a small persistent slab avalanche on an east facing feature at 2000 m, failing on the mid-January surface hoar.On Friday numerous small wind slabs 15 to 20 cm in depth were observed on small north facing rolls around 2000 m. There was also a report of a natural avalanche underneath a large cornice, photos here.

Snowpack Summary

Saturday delivered warmth and wind to the region, followed by 10 to 15 cm of new snow and a very strong wind event on Sunday. This MIN report provides a good description along with some photos that encompass conditions Sunday. The weekend weather left a crust on steep south facing aspects and redistributed quite a bit of snow into potentially deep wind slabs in lee features at and above treeline. 15 to 45 cm of snow continues to consolidate above the mid-January persistent weak layer (PWL). This PWL is made up of large surface hoar that is most prevalent at and below treeline, with enhanced reactivity noted between 1500 and 1800 m. On steep solar aspects this interface presents as a crust, there may be locations where the surface hoar actually sits on the crust.The middle and lower portions of the snowpack are generally well-settled and strong.

Problems

Persistent Slabs

15 to 45 cm of snow sits above a weak interface of surface hoar and crust. The recent warm to cold temperature transition has allowed a more cohesive slab to form above the surface hoar which is most prevalent at and below treeline.

Use extra caution around steep open terrain features, such as cutblocks, gullies and cutbanks.Avoid convex rolls at and below treeline where buried surface hoar may be preserved.Take heed of obvious signs of instability such as whumpfing, shooting cracks and recent avalanches.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Wind Slabs

Variable wind over the weekend has formed widespread wind slabs. These wind slabs may rest on a crust, or perhaps even buried surface hoar near treeline.

Carefully evaluate bigger terrain features on an individual basis before committing to them.Avoid areas where the snow feels stiff and/or slabby.Be careful around freshly wind loaded features, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Jan 29th, 2019 2:00PM