Avalanche Forecast

Issued: Feb 9th, 2016 9:14AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs, Loose Wet and Storm Slabs.

jlammers, Avalanche Canada

Northwest Coastal.

There is a great deal of uncertainty regarding how the snowpack will recover from recent storm loading and very warm temperatures. I would manage this uncertainty with conservative terrain selection.

Summary

Confidence

Moderate - Due to the number of field observations on Tuesday

Weather Forecast

A series of relatively weak Pacific moisture systems will impact the region over the forecast period. On Wednesday and Friday expect 5-10cm of moist snow each day while only trace amounts are expected on Thursday. Freezing levels should drop gradually from 1800m on Wednesday to about 1000m by Friday. Ridgetop winds should remain mainly moderate to strong from the southwest.

Avalanche Summary

A widespread natural avalanche cycle to size 3 took place on Monday in response to recent storm loading and then rain. Avalanche types observed were loose wet, wet slabs, storm slabs and persistent slabs. I'm sure more of the same was observed on Tuesday with rising freezing levels and localized solar radiation. Cooling with help reduce avalanche activity; however, the forecast cooling trend is so gradual it's tough to say exactly when or to what extent.

Snowpack Summary

On Sunday a warm, wet and windy storm added mass and reactivity to recently formed storm slabs. 24 hour snow totals were around 40cm in the Terrace area with closer to 70cm falling in the mountains around Stewart. Rain on Monday, and then rising freezing levels and solar radiation on Tuesday have likely left most surfaces moist or wet. This warming has had a significant destabilizing effect on the snowpack. The January 9th surface hoar/facet layer is down 70-200 cm and remains a concern, especially with heavy and/or thin-spot triggers. Around the same depth you may also find a surface hoar/facet interface from around New Years. There continues to be a lot of uncertainty regarding the reactivity and distribution of this destructive persistent avalanche problem; however, warm temperatures have increased the likelihood of triggering these layers where they still exist. A very conservative approach to mountain travel is still required.

Problems

Persistent Slabs

Recent storm loading, solar radiation and skyrocketing freezing levels have increased the likelihood of waking-up deep and destructive persistent weak layers. Cornice falls may also trigger a persistent slab avalanche.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Do not travel on slopes that are exposed to cornices overhead.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Loose Wet

Elevated freezing levels on Wednesday may promote ongoing loose wet avalanche activity. Loose wet avalanches may also step down to deeper, more destructive layers.

Be cautious of wet sluffing in steep terrain.>Stick to non-avalanche terrain or small features with limited consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Storm Slabs

Recently formed storm slabs may remain sensitive to human triggering on Wednesday, especially in the north of the region where recent accumulations were the greatest and more recent temperatures remained cooler.

Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Feb 10th, 2016 2:00PM