Archived

Avalanche Forecast

Feb 9th, 2016–Feb 10th, 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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Avalanche hazard will decrease as the temperature cools, however the timing of how this will happen is difficult to forecast.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Wednesday

Weather Forecast

A strong temperature inversion persist with an above freezing layer in the alpine. Valley cloud will linger bellow 1500 to 1800m. WEDNESDAY: sunny with scattered clouds, a freezing level of 2800m, light westerly winds. THURSDAY: mainly cloudy, light westerly winds, freezing level of 2500m. FRIDAY: up to 6mm of light rain or wet snow overnight becoming isolated showers and flurries, light southerly winds, freezing level between 1500m and 2000m.

Avalanche Summary

Monday and tuesday saw lots of loose wet avalanche activity up to size 2. Near Rossland, three size 1.5, skier triggered avalanches were reported over the weekend that occurred in wind loaded features between 1800m and 1900m on the late January surface hoar.

Snowpack Summary

Moist snow can be found on solar aspects. A thin melt freeze crust may form on the surface overnight. Increasingly hard to trigger wind slabs can be found at ridgeline. A layer of surface hoar has been observed around Rosland and in the Bonnington Range, buried down 40cm, in open areas at and just below treeline. In most other parts of the region a rain crust can be found at this same depth that extends up as high as 2100m. Below this, a thick slab rests on a layer of surface hoar that was buried earlier in January and is now down 80-130 cm. This layer remains a concern in at and bellow treeline. Before the recent warm up it was producing sudden planar fractures in snowpack tests under moderate to heavy loads. A rain crust from early December sits near the base of the snowpack.

Avalanche Problems

Wind Slabs

Stubborn wind slabs may be lingering on north aspects in the alpine where the snow has stayed cool.

Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1 - 3

Loose Wet

We may see some lingering loose wet avalanche activity before the clouds roll in.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

I would give it a couple more days to see how the warm temperatures have affected the reactivity of buried weak layers in the snowpack.

Be aware of the potential for large avalanches due to the presence of buried surface hoar. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 5