Archived

Avalanche Forecast

Jan 19th, 2014–Jan 20th, 2014

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Cariboos.

Confidence

Fair - Due to the number of field observations

Weather Forecast

A ridge of high pressure will continue to dominate the region bringing dry conditions for the forecast period. An inversion is likely on Monday with valley cloud, clear skies above and alpine temperatures hovering at about 0.0. On Tuesday and Wednesday expect increasing high cloud and freezing levels at about 1400m. Winds should remain light out of the west/northwest for the forecast period. No significant precipitation is expected for at least a week.

Avalanche Summary

Recent explosives avalanche control in the region produced 2 size 3 slab avalanches which failed at ground level. They occurred on a northeast aspect, likely on upper elevation slopes.On Saturday, a size 2.5 deep persistent slab avalanche was reported to have failed naturally on a southeast facing slope at about 2300m. The avalanche failed on basal facets. On the same day, a snowmobiler triggered what appears to be at least a size 2 slab avalanche form a rocky alpine slope in the Allen Creek area. Little is known about the avalanche.

Snowpack Summary

Snowpack depths vary, but in general there is now 200 to 250cm of snow at tree line and as much as 300 cm in select places in the alpine. In some areas we're still dealing with a relatively thin snowpack. Roughly 100cm of well settled storm snow exists as a stubborn hard wind slab in many areas. Heavy wind scouring is reported to have occurred on many exposed windward slopes. Steep, sun exposed features are most likely seeing a daily melt-freeze cycle while surface hoar has been growing in shaded terrain. Below the recently formed storm slab you may find surface hoar buried around January 8th. Its distribution and reactivity seems highly variable. Where it exists, reactivity seems most likely below treeline.A basal facet/crust combo (weak sugary snow above and below a crust) near the ground is still a concern in some areas, and was the culprit with some of the very large recent avalanches. Likely triggers at this interface would include cornice fall, rapid temperature changes or thin spot triggering on an unsupported alpine or treeline elevation slope.

Avalanche Problems

Deep Persistent Slabs

Although deep persistent slab avalanches may become less likely over the next few days, the consequences of a release would be severe. Possible triggers include cornice fall, rapid temperature change or a heavy load over a thin spot.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Avoid convexities or areas with a thin or variable snowpack.>Conditions have greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6

Wind Slabs

Some operators are still expressing concern for wind slabs that were formed last week. Although they may have gained considerable strength, triggering may still be possible in steep, unsupported terrain.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 4