Avalanche Forecast

Issued: Feb 10th, 2015 6:08PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Touchy avalanche conditions right now. Explosives continue to trigger large avalanches with 95% of the shots. It is a good time for conservative terrain choices!

Summary

Weather Forecast

The warm weather continues. Freezing levels will be rising to ~1900m during the days with light freezes overnight. Little precipitation in the forecast period with partially cloudy skies. Winds have been light but will be picking up to moderate from the West starting on Wednesday.

Snowpack Summary

45 - 70 cm of recent storm overlies a crust from January 30th. The recent heavy precipitation, and warmer temperatures have created very touchy storm slabs over top of the January 30th crust interface. Despite a weak freeze last night isothermal conditions persist at treeline and below.

Avalanche Summary

Avalanche control over the past four days in Banff, Yoho Park and Kootenay Park have produced numerous avalanches up to size 3. Most of the avalanches started dry and turned wet at lower elevations. Also, evidence of a widespread cycle up to size 3.5 throughout the forecast region. Some avalanches running close to full path.

Confidence

Due to the number and quality of field observations

Problems

Storm Slabs

Fifty to 90 cm of storm snow exist on the January 30th crust interface. A poor bond exists at this interface and large avalanches have been observed running on this layer. Huge propagations are still possible.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Avoid freshly wind loaded features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Loose Wet

A weak temperature crust overlies isothermal conditions at treeline and below elevations. Many loose wet avalanches that have gouged down to ground have been observed in past 48 hours.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Deep Persistent Slabs

The base of the snowpack remains weak due to basal depth hoar/facets. Additional snow load, or a storm slab failure may trigger large to very large avalanches in thin snowpack areas.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Feb 11th, 2015 4:00PM