Avalanche Forecast

Issued: Feb 15th, 2018 4:46PM

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

shorton, Avalanche Canada

South Coast Inland.

Heavy snowfall in the southern part of the region on Friday will make conditions more dangerous than in the north.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

FRIDAY: Flurries easing throughout the day with 10-20 cm of new snow in the south and trace amounts in the north, moderate west wind, alpine high temperatures around -6 C in the north and -3 C in the south.SATURDAY: Moderate snowfall with 10 cm throughout the day in the north and 30 cm in the south, strong southwest wind, alpine high temperatures around -6 C in the north and -2 C in the south.SUNDAY: Clearing and cooling with strong northeast wind and alpine high temperatures around -18 C in the north and -8 in the south.

Avalanche Summary

No new avalanches were reported on Thursday. On Wednesday, several size 2 wind slabs (40 cm thick) were triggered with explosives on south-facing slopes in the Duffey area. Wind slab activity has been reported in the northern part of the region over the past week, including some small (size 1) skier triggered slabs and some larger (size 2-3) naturally triggered slabs on a range of aspects in alpine terrain (some of which were triggered by cornices).Expect the incoming snow to form fresh slabs, particularly in wind-affected terrain.

Snowpack Summary

Southern parts of the region are expecting heavy snowfall on Friday and Saturday, likely forming fresh storm slabs as snow accumulates. Northern parts of the region are getting lighter amounts, so fresh slab development will primarily occur in wind-affected terrain.A few interfaces buried 10-20 cm below the most recent snow could potentially support wide propagations in the fresh storm/wind slabs. These include scoured crusty surfaces on south-facing alpine slopes, a melt-freeze crust up to about 1900 m, and old wind slabs on a range of aspects at high elevations. The mid-January crust is now buried beneath 80-150 cm of settled snow and may remain sensitive to large triggers - especially in thinner snowpack areas in the north part of the region. Large, looming cornices exist, they are fragile, and they demand respect. Cornice falls are very effective triggers for avalanches on the slopes below them.

Problems

Wind Slabs

The Coquihalla may get 20 cm of new snow on Friday, which will result in touchy slabs in wind-affected terrain. Northern parts of the region have older wind slabs on a wide range of aspects.

Approach steep lee and cross-loaded slopes with caution.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Minimize exposure during periods of heavy loading from new snow and wind.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Large, looming cornices have formed along ridgelines. They need to be given an extra wide berth from above and below. A large cornice collapse in the north of the region may have the ability to trigger a deeply buried weak layer.

Firm cornices can pull back into flat terrain at ridgetop if they fail.Falling cornices may trigger large avalanches on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Valid until: Feb 16th, 2018 2:00PM