Archived

Avalanche Forecast

Feb 12th, 2016–Feb 13th, 2016

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

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

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Columbia.

Avalanche conditions could vary dramatically between aspects and elevations Decision making may be more tricky than the Moderate danger rating implies.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Saturday

Weather Forecast

SATURDAY: Mainly cloudy with continued light snowfall bringing another 1-3cm of accumulation. Freezing levels around 1300m and winds are expected to be light from the southwest. SUNDAY: Another 5-10cm possible overnight before continued light snowfall brings1-3cm of accumulation throughout the day. Freezing levels rising throughout the day to as high as 1500m and winds are expected to be light from the southwest. MONDAY: Moderate rain/snow with freeing levels around 1800m.

Avalanche Summary

Reports from Wednesday include limited results with explosives control producing only one Size 2.5 persistent slab avalanche releasing on the early-January surface hoar down 100cm in a lower elevation start zone where previous surface hoar growth was prevalent. Reports from Thursday include more evidence of recent persistent slab avalanche activity running on the early January surface hoar, with a two-day old 60cm deep Size 2.5 observed on a south facing alpine slope.

Snowpack Summary

A supportive near surface crust is likely in most places aside from shaded aspects at treeline elevations, and lower elevations that are under melt-freeze conditions. This crust and perhaps new surface hoar (where it survived the heat, rain and sun) could be buried by as much as 15-20cm of fresh snow or deeper wind slabs. Avalanche professionals are still monitoring the persistent weakness buried early January, which is now down 80-120 cm. In most places it is no longer sensitive to light triggers. However, in specific locations it still produces hard, but sudden results in snowpack tests.

Avalanche Problems

Wind Slabs

Touchy fresh pockets of wind-deposited snow are lurking on the downwind side of ridgecrests and terrain features. Expect them to get bigger and touchier throughout the weekend.

Use ridges or ribs to avoid wind loaded slopes.>Be cautious as you transition into wind affected terrain.>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 - 3

Deep Persistent Slabs

A deeply buried weak layer can still be triggered in some places, creating very large avalanches.

Be cautious of open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 5