Archived

Avalanche Forecast

Dec 27th, 2019–Dec 28th, 2019

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: Lizard-Flathead.

Triggering large deep persistent slab avalanches remains a concern. Travel with caution and avoid steep rocky terrain.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

FRIDAY NIGHT: Clear with cloudy periods, light wind from the northwest, alpine temperatures drop to -12 C.

SATURDAY: Mix of sun and cloud, light wind from the west, alpine high temperatures around -8 C.

SUNDAY: Cloudy with some light flurries and 2-5 cm of snow, light wind from the north, alpine high temperatures around -8 C.

MONDAY: Mix of sun and cloud, light wind, alpine high temperatures around -8 C.

Avalanche Summary

Avalanche activity is on the decline following the intense storm and avalanche cycle last weekend. During the storm very large (size 3) avalanches occurred naturally and with explosive triggers. On Monday and Tuesday more large avalanches (size 2-2.5) were triggered with explosives, and then on Wednesday and Thursday only smaller (size 1-2) avalanches were reported. Some smaller (size 1) wind slab avalanches have also been triggered by riders over the past few days.

While the likelihood of triggering a deep persistent slab avalanche is on the decline, there is still a fair bit of uncertainty about this problem, and the consequences of triggering such a large avalanche are severe.

Snowpack Summary

Fresh wind slabs are forming at higher elevations while sheltered areas have 10-30 cm of low density snow. The loose snow overlies a hard rain crust below 1700 m. Weak snow and decomposing crust layers can be found near the bottom of the snowpack (80-140 cm below the surface). Intense loading from last weekend's storm resulted in very large (size 3) avalanches on these layers. Although the strength of these layers has improved to some degree since then, a complex deep persistent slab avalanche problem persist (check out latest forecaster blog here).

Terrain and Travel

Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Choose slopes that are well supported and have limited consequence.
Conditions may have improved, but be mindful that deep instabilities are still present.
Be carefull around freshly wind loaded features.