Avalanche Forecast

Issued: Feb 1st, 2019 6:12PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Loose Dry and Deep Persistent Slabs.

Conrad Janzen, Parks Canada

Banff Yoho Kootenay.

The avalanche hazard will rise overnight and into Saturday with additional snow and wind. Northern areas will receive the greatest amounts. Stick to conservative lines and avoid steep overhead terrain until the new snow has a chance to bond.

Summary

Weather Forecast

Snow through Saturday with another 10-25 cm at treeline. Northern areas will see the highest amounts. Winds remain in the moderate range with strong gusts out of the SE to SW depending on how the cold front behaves. Temperatures remain in the -5 to -15 range before plummeting Saturday night. Flurries and very cold temps on Sunday.

Snowpack Summary

15-35 cm of new snow with moderate SW-SE winds is building slabs in lee areas of the alpine. The mid-pack is quite dense above the Dec 10 interface down 70-140 cm. In shallower snowpack areas weak facets exist below the Dec 10 interface, with moderate-hard test results in the facets. In deeper snowpack this basal weaknesses is less pronounced

Avalanche Summary

Local ski hills reported ski cutting small loose dry and wind slabs up to size 1.5 on Friday in steep lee areas. No reports or avalanche observations from the back-country, but we expect an increase in avalanche activity over the next 36 hrs.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Storm Slabs

We expect 20-50 cm of storm snow by Sunday with moderate-strong SW-SE winds. Storm slabs will form in many areas. Natural avalanches are expected in steep terrain and human triggering will be likely in deeper storm snow areas.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas in the alpine and treeline. Storm snow is forming reactive slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Loose Dry

Loose dry avalanches are expected in steep terrain and gullies. Climbers and skiers should avoid overhead hazard until the new snow has a chance to bond.

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

Elevations: Alpine.

Likelihood

Very Likely

Expected Size

1 - 2

Deep Persistent Slabs

The new snow load may start waking up the Dec 10th deep persistent facet weakness down 60-140 cm. This is of greatest concern in shallow snowpack areas where the basal facets are weakest.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Avoid thin, rocky or unsupported slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 2nd, 2019 4:00PM