Archived

Avalanche Forecast

Dec 2nd, 2012–Dec 3rd, 2012

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

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

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: Glacier.

Recent natural avalanches from steep paths have been triggered by loading. Minimize your exposure; spread out while crossing paths like "Frequent Flyer", and the higher track up Connaught to avoid exposure to "STS" (aka Cheops N4) is advised.

Weather Forecast

The moist and mild weather will continue; another pulse of intense precip and wind is expected mid-day, followed by scattered flurries through Monday. Freezing levels will remain at valley bottom. Mod to strong S-W winds will load slopes. On Tuesday, another system will bring heavy precip, with freezing levels rising to 12-1500m.

Snowpack Summary

A new storm slab is forming; 40cm of storm snow fell in the last 3 days. Moderate-strong S'ly winds will have formed windslabs and fat pockets on lee slopes. This overlies the Nov28 layer which will be most reactive where surface hoar was buried; sheltered areas at treeline. The Nov 6 crust is facetting and may become reactive with increasing load.

Avalanche Summary

Yesterday, distinct avalanche cycles occurred during periods of intense loading by wind and snow. 1 size 3 and 22 size 2-2.5 natural avalanches were observed from paths above the highway, east of Rogers Pass. These occurred from steep complex terrain, some avalanching repeatedly. Skiers reported seeing an avalanche in "frequent flyer" path.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

We've received 40cm of snow in the past 3 days. This soft slab will be most reactive where it buried surface hoar or sun-crust. We expect more snow and strong winds today, which may overload these layers resulting in natural avalanches.

Choose well supported terrain without convexities.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Winds picked up yesterday, and there is lots of new snow available for transport. S-SW winds loaded lee slopes, triggering natural avalanches in steep terrain. Expect touchy loaded pockets, and soft windslabs on lee slopes.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.Avoid avalanche terrain during periods of heavy loading from new snow and wind.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Persistent Slabs

The Nov 6 crust complex has yet to wake up. While the likelihood of triggering is low, it will produce large avalanches. As the load on this layer increases, it may become reactive. Smaller avalanches may step down to this deeper layer.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4