Avalanche Forecast

Issued: Jan 4th, 2017 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

While the danger rating is moderate by definition, forecasters still have low confidence in certain areas of the forecast region (Lake Louise). Exercise restraint and make conservative terrain choices for a few days yet.

Summary

Weather Forecast

Finally, some respite from the cold temps with increases warming to the -10 range through Thursday. Increased cloud cover and small amounts of precip up to 5mm. Wind will shift from North to West and decrease in velocity late on Thursday.

Snowpack Summary

20-30 cm of last weeks storm snow sits over top of the Dec 19 layer facet layer which in turn sits on the Nov 12 crust. Winds over the past week have created wind slabs in exposed areas. In many places these wind slabs sit on a weak snowpack comprised of facets and depth hoar.

Avalanche Summary

No natural activity was reported or observed today. However, Lake Louise and Sunshine Village patrollers/forecasters were able to trigger a few wind slabs with explosives up to size 2.

Confidence

Wind effect is extremely variable

Problems

Wind Slabs

Wind slabs up to 40 cm thick exist in the alpine and some treeline locations. Even a small wind slab has the potential to step down into the weak facetted mid-pack resulting in a bigger avalanche.

Be careful with wind loaded pockets while approaching and climbing ice routes.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

The mid and lower pack is weak and facetted, and will remain this way for the foreseeable future. This layer is most concerning in areas where a cohesive slab overlies this weak foundation.

Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Jan 5th, 2017 4:00PM