Archived

Avalanche Forecast

Dec 9th, 2014–Dec 10th, 2014

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

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

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: Purcells.

The warm, wet, windy storm continues. Backcountry ski conditions are reported to be terrible and avalanche hazard remains elevated. Now is a good time for indoor activities or take your rain gear with you to your local ski hill.

Confidence

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

Weather Forecast

The storm system continues to bring warm, wet conditions to the interior for Wednesday and Thursday. The Purcells region can expect another 5-10mm on Wednesday and 10-15mm for Thursday. Freezing levels on both days are expected to be 2200-2500m. Alpine winds should remain strong but might start to taper off late-Thursday. On a positive note, things should start to change on Friday. Freezing levels should drop, winds should ease, and we may see new snow at higher elevations.

Avalanche Summary

Limited observations on Tuesday includes a report of explosive triggered slabs up to size 1.5 in the Golden area. Also reported was small loose wet activity in the Invermere area.

Snowpack Summary

New moist or wet snowfall sits 10-20cm above a layer of surface hoar. Another 15-20cm below this you may find a hard rain crust. In the Golden area this crust exists up to around 1600m, whereas in the south it is up to 2000m or higher. In total, last week's storm produced slabs up to 1m thick in the north of the region and around 60cm thick in the south. This slab sits on the mid-November weak layer (surface hoar, facets, and/or a crust). Below this you will likely find a 15-20cm thick layer of sugary facets, which is sitting on a solid rain crust from early November. The reactivity of these layers may be slowly diminishing, but they still warrant cautious consideration. Snowpack tests are getting hard pops and drops results, indicating the potential for large propagation and large avalanches.

Avalanche Problems

Storm Slabs

Storm slabs will continue to build at higher elevations as the storm progresses. Strong winds will quickly reload leeward features.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

Likelihood of triggering a deep weak layer is expected to increase with new storm loading and warming. Any slopes that did not avalanche during the last storm cycle should still be considered hazardous. Smaller avalanches may trigger a deep release.

Choose well supported terrain without convexities.>Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5

Loose Wet

Rain at lower elevations will reduce the stability of the upper snowpack and loose wet avalanches are expected in steep terrain.

Be cautious of sluffing in steep terrain.>Avoid areas with steep overhead hazard.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4