Avalanche Forecast

Issued: Jan 29th, 2016 7:48AM

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

ccampbell, Avalanche Canada

Purcells.

Patience and diligence may be required to resist venturing into complex terrain as the snowpack settles and adjusts to the recent load and warming.

Summary

Confidence

High

Weather Forecast

SATURDAY: A mix of sun and cloud with isolated light flurries. Freezing levels around 1200m and light southwesterly winds. SUNDAY: A mix of sun and cloud and mainly dry with freezing levels dropping below valley bottoms and light variable winds. MONDAY: A mix of sun and cloud with isolated light flurries. Freezing levels in valley bottoms and light southwesterly winds.

Avalanche Summary

Reports from Thursday include several natural and human triggered 50-60cm thick persistent slab avalanches up to Size 2 running on surface hoar buried at the beginning of January. Some were remotely triggered by as much as 30m away. Explosives control also produced relatively harmless loose wet and storm slab avalanches

Snowpack Summary

Weakness linger within and under the 30-60cm of rapidly settling recent storm snow with reports of moderate sudden results in snowpack tests. Southwesterly winds have continued to build fresh wind slabs on the leeward side of ridgecrests and behind terrain features on cross-loaded slopes. The persistent weak layer of surface hoar buried early-January is now typically down 40-70 cm and appears to be quite touchy in some parts of the region. In general, the lower snowpack is well settled and strong.

Problems

Wind Slabs

Fresh wind slabs lurking below ridge crests and behind terrain features are sensitive to human triggers. Cornices are also large and fragile.

Be cautious as you transition into wind affected terrain. >Use ridges or ribs to avoid pockets of wind loaded snow. >Avoid freshly wind loaded features. >

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Surface hoar buried at the beginning on January remains a concern for human triggers. The potential for widespread propagation and remote triggering makes this persistent slab particularly tricky to manage.

Be aware of the potential for remote triggers and wide propagations due to a layer of buried surface hoar. >Avoid open slopes and convex rolls at and below treeline, and north-facing alpine slopes, where buried surface hoar may be preserved. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Jan 30th, 2016 2:00PM