Avalanche Forecast

Issued: Jan 14th, 2019 3:40PM

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

jfloyer, Avalanche Canada

South Rockies.

The possibility remains of triggering a deep layer of sugary facets. A diligent approach to avoiding steep, thin and/or rocky slopes is required.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY NIGHT: Clear skies. Temperatures dropping to around -14C.TUESDAY: Dry and sunny above some valley cloud. Expect cool treeline and alpine temperatures, around -4C. Light winds.WEDNESDAY: Dry with a mix of sun and cloud. Treeline temperatures around -6C. Light southwesterly winds.THURSDAY: Light snowfall, 2-4 cm. Treeline temperatures around -9C. Light easterly winds.

Avalanche Summary

On Saturday a size 2 natural deep persistent slab avalanche was observed on a south facing feature around 2100 m, more details here. There is also a great MIN report from the neighboring Lizard Range where a group of sledders share about their near miss on a steep southwest facing feature at ridgecrest.On Friday we received a great Mountain Information Network observation of natural activity on solar aspects, more details here. A size 2-2.5 natural avalanche was also reported on a north aspect at 2200 m on Friday. This avalanche was likely triggered by a rock fall, and ran on the deep persistent layer at the base of the snowpack.

Snowpack Summary

Recent warm alpine temperatures have created moist/crusty surfaces on southerly aspects. The snow appears to have remained dry on northerly aspects.Large variability in snow depths still exists in the region, ranging from almost no snow to nearly 200 cm in some areas. For average snowpack areas, expect to find weak and sugary faceted snow around 50 to 100 cm deep, which extend to the ground. This weak bottom half of the snowpack has been the culprit for large avalanches in the region over the past few weeks.

Problems

Deep Persistent Slabs

Deeply buried weak layers remain a concern, especially as temperatures rise and the sun comes out. Large loads like cornices may trigger this layer as well, and cornice failures become more likely during warm, sunny conditions.

Avoid steep slopes in areas with a thin or variable snowpack.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Wind Slabs

Small wind slabs may be triggerable from wind loaded slopes. The real danger is if a small slab stepped down to the lower weak layer.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Minimize exposure to steep slopes on warm or sunny days.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 15th, 2019 2:00PM