Avalanche Forecast

Issued: Apr 1st, 2017 3:43PM

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

cgarritty, Avalanche Canada

North Columbia.

The snowpack still hasn't adjusted to spring weather at high elevations. Keep your guard up and an eye on overhead hazards while persistent slab problems are still in play.

Summary

Confidence

Moderate -

Weather Forecast

Saturday night: Scattered flurries bringing up to 5 cm of new snow. Light southwest winds.Sunday: A mix of sun and cloud with scattered flurries and about 5 cm of new snow. Light west winds. Freezing level to 1400 metres with alpine temperatures around -7.Monday: A mix of sun and cloud. Light northwest winds. Freezing level to 1500 metres with alpine temperatures around -6.Tuesday: Cloudy with sunny periods. Light southeast winds. Freezing level to 1800 metres with alpine temperatures aroundÂ -4.

Avalanche Summary

Reports from Friday showed several deep persistent slab releases to Size 3.5 having occurred within the previous 24 hours with natural, cornice fall, and rider triggers. One of these featured a crown fracture of up to 3 metres in depth. Numerous wind slabs were also observed releasing naturally to Size 2.5 while natural loose wet and loose dry slides ranged from Size 1.5-2.Reports from Thursday include numerous observations of storm slabs releasing naturally from Size 1-2.5 throughout the region. Natural triggers (including natural cornice fall) featured prominently in reports. Crown fractures generally ranged from 30-40 cm and northeast to northwest aspects were the most active.On Wednesday, numerous storm slabs up to Size 2.5 were observed. Several Size 1 storm and wind slabs were also reactive to rider triggering.

Snowpack Summary

About 10 cm of new snow fell over Friday night and Saturday morning, burying a temperature crust at about 1900 metres and below as well as sun crust all the way into the alpine on most solar aspects. The new snow brings recent storm snow totals at upper elevations to 40-60 cm. This storm snow is dry up high and moist at 1800 m and below. 90-130 cm of accumulated snow now overlies a rain crust below 2000 m and sun crust on solar aspects at higher elevations. New wind slabs are developing on leeward slopes and behind terrain features and large, fragile cornices exist along ridgelines. At higher elevations, the February weak layers are down 150-190 cm and woke up during last week's storm with many avalanches stepping down to them. The deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack and a few avalanches and cornice falls have also stepped down to these layers last week resulting in some very large full depth avalanches. These layers remain a real concern while touchier wind slabs and cornices continue to present the risk of acting as a trigger for deeper weaknesses.

Problems

Storm Slabs

Recent snow and wind have formed storm slabs that may remain reactive to human triggering on Sunday. This problem is more pronounced in wind affected areas at higher elevations, so be vigilant for signs of recent wind loading.

Be especially careful with wind loaded pockets near ridge crests and roll-overs.Minimize exposure to sun exposed slopes if the sun comes out.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Persistent Slabs

Large, destructive avalanches have recently been reported running on deeply buried weak layers. Cornice fall and smaller storm slab avalanches have been common triggers for these slides, which have the potential to reach the end of runout zones.

If triggered, slab avalanches or cornices may step down to deeper layers.Avoid lingering in runout zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

Loose Wet

Daytime warming and/or solar radiation may deteriorate the surface of the snowpack at lower elevations and on solar aspects. Snow that becomes moist will have the tendency to sluff from steep terrain, either naturally or with a human trigger.

Use extra caution on slopes if the snow is moist or wet.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 2nd, 2017 2:00PM