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Avalanche Forecast

Jan 26th, 2019–Jan 27th, 2019
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
1: Low
The avalanche danger rating in the alpine will be low
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Cariboos.

Fresh wind slab formation is expected Sunday in the alpine, but our main concern is still the surface hoar down 15 to 40 cm which is most prevalent between 1500 and 1800 m, this interface likely remains sensitive to human triggering.

Confidence

Moderate -

Weather Forecast

Sunday marks the start of a pronounced ridge of high pressure that is expected to be with us through at least Tuesday. This period is marked by clearer skies, cooler temperatures and a lack of precipitation.SATURDAY NIGHT: Freezing level returning to valley bottom overnight, strong to extreme west wind, 2 to 10 cm of snow possible.SUNDAY: Scattered cloud cover initially, clearing in the afternoon, freezing level at valley bottom, moderate to strong northwest wind, trace of snow possible.MONDAY: Mostly clear skies in the morning with cloud cover increasing throughout the day, freezing level at valley bottom, light northwest wind, no precipitation expected.TUESDAY: Clear skies, freezing level at valley bottom, light variable wind, no precipitation expected.

Avalanche Summary

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. A few natural wind slabs, storm slabs and dry loose avalanches up to size 2.5 were reported on Wednesday and Thursday on steep slopes on a variety of aspects at treeline and alpine elevations.

Snowpack Summary

15 to 40 cm of snow sits above a layer of large surface hoar crystals and sun crust. In areas that have had wind effect the recent snow has been settling into a thin but reactive slab above this weak layer, with enhanced reactivity noted at elevations between 1500 and 1800 m. In sheltered areas the snow is faceting and lacks cohesion above this layer which is only reactive as dry loose sluffing. Slightly warmer temperatures are starting to consolidate the upper snowpack which will likely make slab avalanches more sensitive to human triggering. The middle and lower portions of the snowpack are generally well-settled and strong.

Avalanche Problems

Persistent Slabs

15 to 40 cm of snow rests above a weak layer comprised of surface hoar and sun crust. Where the snow has formed a cohesive slab, such as in windy areas, it is reactive to human triggering, especially between 1500 and 1800 m.
Be cautious around open terrain features, such as cutblocks, gullies, and cutbanks.Watch for signs of instability such as whumpfing, cracking and recent avalanches.Expect to find deeper pockets of wind loaded snow in wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Wind Slabs

Northwest wind is expected to pick up Saturday night and should continue through the day Sunday. Watch for fresh wind slab formation which is expected to be most prevalent in the alpine.
Be aware of the potential for wide propagations due to a reactive weak layer under fresh wind slabs.Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.Carefully evaluate steep lines for wind slabs.

Aspects: North East, East, South East, South, South West.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 2