Avalanche Forecast

Issued: Jan 25th, 2016 8:38AM

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

rbuhler, Avalanche Canada

South Columbia.

The current conditions require restraint and conservative decision-making. Triggering the weak layer is getting more difficult but large avalanches, even from relatively low-angle slopes, remain possible. New wind slabs may also form on Tuesday.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

A weak storm pulse is expected to bring 5-10cm of new snowfall to the region on Tuesday. Freezing levels are expected to be around 1500m and alpine winds are forecast to be moderate to strong from the southwest. A mix of sun and cloud is expected for Wednesday with freezing levels reaching around 1500m and light to moderate southwest winds in the alpine. A more substantial storm front is expected to reach the region on Wednesday night or Thursday morning. 15-25cm of snowfall is currently being forecast with freezing levels around 1700m and strong southwest winds.

Avalanche Summary

Numerous slab avalanches up to size 3 were reported over the weekend. Most of the natural avalanche activity occurred on Friday and Saturday but several were still reported on Sunday. A large number of skier triggered avalanches were also reported. Many of these failed at treeline and below on buried surface hoar down 30-60 cm. Many of these were triggered remotely, highlighting the volatility of the persistent slab. An increasing number of wind slabs have also been failing at alpine/ treeline elevations, and also running on surface hoar. While the natural activity tapered off since Saturday, the persistent slab is expected to remain reactive to human triggering for several more days. New wind slabs may form on Tuesday with the progression of the weak storm system.

Snowpack Summary

Recent snowfall and strong winds have created some storm slabs but reactive wind slabs on features lee to the southerly winds seems to be the bigger concern in the upper snowpack. This has added additional load and stress to an already touchy persistent slab. This 40-90 cm thick persistent slab overlies a variety of surfaces including large surface hoar, sun crusts, rime crusts and facets. The slab is ripe for human and natural triggers and is especially touchy at and below treeline. The mid and lower snowpack are generally well settled and strong.

Problems

Persistent Slabs

Large avalanches have been failing on a buried persistent weak layer down 40-80 cm. This problem will likely remain sensitive to human triggers for the next few days.

Be aware of thin areas that may propogate to deeper instabilites.>Use conservative route selection and be aware of the possibility of remote triggering.>Avoid steep open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

New wind slabs may form in leeward features on Tuesday. It may still be possible to trigger deep older wind slabs in exposed lee and cross-loaded terrain near ridge crests.

Use ridges or ribs to avoid wind loaded slopes. >Avoid freshly wind loaded features. >Be cautious as you transition into wind affected terrain. >

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Jan 26th, 2016 2:00PM