Archived

Avalanche Forecast

Feb 9th, 2013–Feb 10th, 2013

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

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: Northwest Inland.

Confidence

Poor - Due to limited field observations

Weather Forecast

Synopsis: Several low intensity pulses of precipitation will bring light snowfall through the period.Sunday: Flurries, with some breaks. Southwesterly winds around 30 km/h at ridgetop. Freezing level around 1300m.Monday and Tuesday: Light snow (2-4 cm each day). Southwesterly winds gusting to 70 km/h at ridgetop. Freezing level around 500 m.

Avalanche Summary

Recent loose snow avalanches have been reported during recent warm weather.

Snowpack Summary

Around 20-40cm recent new snow sits on a variety of old surfaces, which vary from facets to crusts and isolated pockets of surface hoar (sheltered treeline and below treeline). There is very limited information about the nature of the interface, with the only results suggesting reactivity in sheltered, shady treeline and below treeline slopes (preserved surface hoar). I would stress the importance of digging down to find and test weak layers.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

Avalanche Problems

Wind Slabs

New snow and shifting winds have built wind slabs that are likely found behind terrain breaks such as ridges and ribs. Watch for katabatic winds descending from glaciers.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 5

Persistent Slabs

Buried beneath the new snow sits a surface hoar/crust/facet weakness. This may be sensitive to rider triggers in steeper sheltered terrain or over convex rolls, especially at treeline and below treeline elevations.

Dig down to find and test weak layers before committing to a line.>Assess start zones carefully and use safe travel techniques.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 6