Avalanche Forecast

Issued: Jan 22nd, 2015 8:57AM

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

ccampbell, Avalanche Canada

Northwest Inland.

The last system dumped more snow than forecast to parts of the region. If this pattern continues expect periods of HIGH avalanche danger over the next few days.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Moderate to heavy snowfall or rain is expected to continue throughout the forecast period with 10-20 cm of snow (or mm of rain) each day for Friday, Saturday, and Sunday, although Friday is looking perhaps a little drier. Strong southwesterly winds are expected to ease off on Saturday and remain light to moderate on Sunday. Freezing levels around 1500 m on Friday are also expected to drop off to near valley bottom on Saturday, but fluctuate on Sunday.

Avalanche Summary

Periods of heavy snow or rain, strong ridge winds, and warming will probably tip off a natural avalanche cycle in parts of the region. We could see wet activity at lower elevations with storm/wind slabs where snow accumulates. There is also potential for deep persistent weaknesses to be overloaded producing isolated very large and deep slides.

Snowpack Summary

Warm temperatures have promoted rapid slab settlement and wet loose surface snow at lower elevations, while southwest winds continue to build slabs on leeward slopes with cornices overhead in exposed treeline and alpine terrain. A recent report from the Ashman area mentioned whumpfs and other signs of instability associated with roughly 30 cm of recent snow rapidly settling into a slab under warm temperatures and significant wind. A surface hoar layer buried at the start of January may be around 40-60 cm deep now. In the mid-pack, a crust weakness buried in mid-December seems to be unreactive for the time being. Near the base of the snowpack is the crust-facet combination buried in November that could remain problematic, especially in shallower snowpack areas with heavy loading and warming.

Problems

Storm Slabs

Weaknesses could exist within or under the new storm snow. Expect deep and dense wind slabs to form in exposed NW-NE facing terrain.

Stick to simple terrain and be aware of what is above you at all times.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Wet Slabs

It will probably be pretty wet at lower elevations (below ~ 1500m). Steer clear of slopes with open glide cracks and terrain traps.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

Heavy loading from snow and/or rain could trigger deep persistent weaknesses and produce isolated very large avalanches.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 6

Valid until: Jan 23rd, 2015 2:00PM