Avalanche Forecast

Issued: Jan 26th, 2015 4:00PM

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

grant statham, Parks Canada

Banff Yoho Kootenay.

Although we are past the peak of the current avalanche cycle, we expect one more day of warm temperatures and have kept the BTL danger rated as HIGH. Conditions will improve dramatically with the onset of more seasonal temperatures on Thursday.

Summary

Weather Forecast

Slowly, ever so slowly, the temperatures are starting to fall.Â Overnight and Tuesday expect freezing levels to drop below treeline with lows of -4 in some areas.Â No precipitation is expected through the remainder of the week as the slow cooling continues.Â By Thursday temperatures are expected to hit -12, which should lock the snowpack down.

Snowpack Summary

Warm temperatures are having a dramatic effect on the snowpack. Below 2000m the snowpack is wet and isothermal in many areas, particularly on sun exposed terrain and around rocks. Above 2000m moist snow has been blown to smithereens by yesterdays wind and deep, drifted windslabs can be expected in alpine areas. The snowpack is in a very weak state.

Avalanche Summary

A widespread avalanche cycle occurred on Sunday with dozens of large avalanches observed on all aspects, and at all elevations with lower elevations being particularly active. Monday saw less activity, but avalanche control near Mt Wilson produced a large avalanche onto the 93N highway. Avalanches continue to be reported every few hours.

Confidence

Problems

Loose Wet

Wet avalanches will continue to occur on Tuesday at low elevations. Ice climbers should avoid avalanche terrain, in particular the gullies where wet avalanches have been running.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Wind Slabs

Very strong SW winds over the past few days have created deep windslabs above treeline. These slabs have the potential to trigger the deeper layers in the snowpack, making for a large avalanches. Avoid all windloaded terrain.

If triggered the 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 snowpack is structurally very weak - one of the weakest snowpacks seen in years - the facets and depth hoar near the base of the snowpack will produce large avalanches when triggered.

Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Valid until: Jan 27th, 2015 4:00PM