Avalanche Forecast

Issued: Feb 14th, 2017 4:02PM

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.

grant statham, Parks Canada

Banff Yoho Kootenay.

Very tricky conditions. Many large avalanches have occurred in the past 72-hours. Although we are past the peak of the cycle, conditions remain ripe for human triggering and natural avalanches. Slopes that have not yet released should be avoided.

Summary

Weather Forecast

Another day of warm temperatures is expected on Wednesday, but this time with a bit more cloud cover and maybe a few flakes of snow. Expect treeline temperatures to reach 5 degrees, and the winds will return to SW 75-100 km/hr. The temperatures will begin to drop again on Thursday, accompanied by some more new snow (5 cm probably).

Snowpack Summary

45 cm of settled snow has formed a cohesive slab overlying a series of weak layers. Test results indicate "sudden" shear failures on these layers, which indicates that they are primed for triggering. Recent strong winds and warm temperatures have tipped the balance, and most slopes that have not avalanche should be considered highly suspect.

Avalanche Summary

Went to Sunshine Village today and was impressed by the widespread avalanche cycle that occurred the last 48-hours - many big, deep avalanches. Avalanche control on Tuesday produced an impressive size 3 avalanche on Vermillion Peak. Patrol up the Icefields Parkway today showed nothing new in the last 24-hr, but lots of large avalanches last 72-hr.

Confidence

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.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.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

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 run full path. We are seeing avalanche activity for the first time this season in many different areas.

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

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.

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

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 15th, 2017 4:00PM