Avalanche Forecast

Issued: Feb 15th, 2017 4:42PM

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

cam_c, Avalanche Canada

North Columbia.

Watch for conditions that change with elevation. Heavy rain at lower elevations means heavy snow up high.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

THURSDAY: 5-15 mm of precipitation with moderate southerly winds and freezing levels around 2000 m.FRIDAY: Unsettled conditions with isolated flurries, moderate becoming light southwesterly winds and freezing levels dropping to 1500 m.SATURDAY: A mix of sun and cloud with flurries possible late in the day, light winds and freezing levels around 1000 m.

Avalanche Summary

Reports from Tuesday include continued natural loose wet avalanche activity up to Size 2 on steep sun exposed slopes. A Size 2 natural storm slab and Size 1 skier triggered wind slab was also reported. On Monday a natural Size 2 wind slab was observed on a northeast aspect at 2100 m failing down 40 cm. Explosives triggered a few Size 2-3 persistent slabs failing on the early February weakness down 50-60 cm. Rain at lower elevations is expected to destabilize the upper snowpack resulting loose wet sluffing and potentially increasing the sensitivity of triggering persistent slab avalanches. In the alpine, touchy new wind slabs have the potential to step down and trigger persistent slab avalanches.

Snowpack Summary

Around 10 cm fresh snow has fallen at higher elevations accompanied by strong southerly winds, while elsewhere the snow surface has become wet, loose and cohesionless from rain and previous sun-exposure. Rapidly settling storm snow from last week is still bonding poorly to the previous snow surface from early February, which is now down 60-80 cm and includes a sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. Recent strong winds from the south and west had redistributed the recent storm snow in exposed terrain forming wind slabs. The mid and lower snowpack are generally well settled and stable in deeper snowpack areas but may be faceted and weaker in shallower areas. The mid-December surface hoar/facet persistent weakness can now be found down roughly 150 cm. This weak layer has become inactive in the south of the region, but may still be lingering in the northern part of the region near Blue River and Valemount. This layer is expected to get tested during the current period of sustained warming.

Problems

Persistent Slabs

A persistent weakness down 50-80 cm remains remains sensitive to light triggers in isolated areas. Smaller avalanches have the potential to step down to this layer.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be aware of the potential for large avalanches due to the presence of buried weak layers.Whumpfing, shooting cracks and recent avalanches are all strong indicators of unstable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Touchy fresh wind slabs are likely lurking below ridgecrests and behind terrain features at higher elevations.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.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.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Loose wet sluffs are expected in steep terrain features at lower elevation. Although generally slow moving, they can easily take you for a ride and run significant distances. They also have the potential to trigger slabs on the slopes below.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Use extra caution on solar slopes or 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, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 16th, 2017 2:00PM