Archived

Avalanche Forecast

Feb 8th, 2016–Feb 9th, 2016

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Banff Yoho Kootenay.

Major warming event for Tuesday - freezing levels to 3500m under sunny skies. Avoid avalanche terrain and DON'T CLIMB UNDER SUNNY START ZONES! Avalanche control planned for Bourgeau, Whymper and Simpson paths - no access to these areas on Tuesday.

Weather Forecast

The most significant warming event of the winter will occur on Tuesday, as freezing levels are forecast to reach 3500 m and temperatures in the high alpine could reach +5 - warmer in sheltered areas when combined with clear skies and sunshine. Strong west winds (50 km/hr) in alpine areas.

Snowpack Summary

A 50-100 cm slab now overlies the January 6 weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. Extreme warming and sunshine forecast for Tuesday will provide the necessary trigger, and slab avalanches are likely in many locations along with cornice failures and wet sluffs in gullies.

Avalanche Summary

The past 48 hours saw a widespread avalanche cycle of natural and human triggered avalanches up to size 3. Evidence of recent avalanches exists in many avalanche paths - most are slabs that failed 50-70 cm deep on the Jan 6 weak layer. Today we observed one fresh size 2 on Mt Whymper on a south facing, windloaded slope at 2400 (crown depth ~100 cm)

Confidence

Freezing levels are uncertain on Tuesday

Avalanche Problems

Persistent Slabs

Expect this problem to produce avalanches on Tuesday, and avoid exposure to avalanche terrain as these will be large avalanches with potentially significant consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Loose Wet

Expect wet snow sluffs and rockfall due to the wet snow - most problematic in low elevation gullies and all south and west facing terrain. Ice climbers should be particularly alert for this.

Avoid ice climbs exposed to steep rocky terrain on solar aspects during the middle of the day.

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

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Cornices

The big warmup will weaken cornices and they can be expected to fall off spontaneously. Avoid overhead exposure to any cornices, but if you must then consider the runout distance and minimize your exposure time.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 3