Avalanche Forecast

Issued: Feb 10th, 2016 7:17AM

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

triley, Avalanche Canada

Northwest Inland.

A gradual cooling trend with forecast precipitation, should bring snow to the alpine and then slowly to lower elevations. Persistent weak layers continue to be a concern for large destructive avalanches.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Light precipitation and strong southwest winds overnight. Freezing levels in the south around 1500 metres, and in the north closer to 500 metres. Broken skies on Thursday with strong southeast winds and continued warm temperatures. Freezing levels dropping down to near valley bottoms by Friday morning. Light precipitation and moderate southwest winds during the day Friday. Continued unsettled weather on Saturday with light precipitation, moderate winds, and freezing levels rising up to 1000 metres in the afternoon.

Avalanche Summary

No new avalanche observations. 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. Cooling will 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

Between 18 and 25cm of new snow fell on Sunday. Strong southwest winds shifted these accumulations into reactive wind slabs in higher elevation lee terrain. Rain on Monday, and then rising freezing levels and solar radiation on Tuesday have likely left most surfaces moist or wet. This warming has also had a significant destabilizing effect on the snowpack. Within the top 50cm you may find a layer of surface hoar which was buried at the beginning of February. This layer was observed in the Hankin area and may exist in many other places. The early or mid January surface hoar layer is generally 50-80 cm deep, although it may be buried by well over 100cm of snow in the far west of the region. Observers have found this persistent weakness on all aspects and at all elevations. It consistently produces moderate "pops" results in snowpack tests. Below this, the Boxing Day surface hoar problem may also be lurking. The mid and lower snowpack is generally quite weak and faceted, especially in lower snowpack areas such as the Babines.

Problems

Persistent Slabs

Recent storm loading, rain, 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.

Be aware of the potential for large, widely propagating avalanches due to the presence of buried surface hoar.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Wind Slabs

New wind slabs are expected to develop with forecast new snow and wind. Watch for reverse loading if the winds shift to the east.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Elevated freezing levels 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.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 11th, 2016 2:00PM