Avalanche Forecast

Issued: Feb 13th, 2017 6:14PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Wind Slabs, Deep Persistent Slabs and Loose Wet.

tim haggarty, Parks Canada

Banff Yoho Kootenay.

With temperatures climbing and the potential for sunny periods on Tuesday, expect both wind slabs and the deep persistent slabs to become more sensitive to natural and human triggering.

Summary

Weather Forecast

Warming temperatures are likely to be the dominant input over the next few days. We expect freezing levels to approach Treeline on Tuesday with diminishing cloud cover however West winds should also be increasing. Watch local conditions carefully and consider heating both at your level and on the slopes above you.

Snowpack Summary

30-60cm of new snow in the past 10 days with extreme winds from the SW have created new slabs over a weak snow pack comprised mostly of facets, buried wind layers, and depth hoar. Further avalanche activity can be expected on these weak facet layers over the next while as the snowpack adjusts to the load and temperatures warm up.

Avalanche Summary

The recent avalanche cycle continued into Sunday when a size 3 avalanche ran to the creek over the Bourgeau Left ice climb. Avalanche control flights Monday observed widespread natural activity and produced windslab and deep persistent slabs of size 2.5 and 3 above the Sunshine Village access road as well as a sz 3 on Vermillion Peak in Kootenay NP

Confidence

Freezing levels are uncertain on Wednesday

Problems

Wind Slabs

Strong to extreme wind on Sunday created wind-slabs and cornices that are ripe for triggering. Slabs are becoming firmer in high start zones. Give avalanche terrain a wide berth as fracture lines may extend further that you expect.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The new snow has created a touchy slab over the weak facets at all elevations. Avalanches could potentially run full path. We are seeing avalanche activity for the first time this season in many different areas.

Minimize overhead exposure; avalanches may reach the end of run out zones.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Loose Wet

With temperatures climbing, all it will take is a brief period of clear skies and calm winds to have a major impact on steep slopes. Small solar or temperature triggered events are likely as the snow becomes moist.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Minimize exposure to steep slopes on warm or sunny days.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 14th, 2017 4:00PM