Avalanche Forecast

Issued: Jan 2nd, 2015 7:23AM

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

Avalanche Canada Peter, Avalanche Canada

We are on the verge of another sharp transition from cold and dry to wet and mild. Avalanche danger is expected to rise quickly on Sunday.

Summary

Confidence

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

Weather Forecast

Synopsis: On Saturday we should see a brief ‘calm before the storm’ with mainly cloudy skies and a chance of flurries. The freezing level remains near valley bottom and ridge winds are generally light. A frontal system reaches the South Coast by Sunday morning dumping 20-30 cm of snow throughout the day. The freezing level should stay close to valley bottom and winds increase to moderate or strong from the SW. Heavy precipitation continues on Monday but temperatures should spike rapidly as the freezing level shoots up over 2000 m early in the day.  

Avalanche Summary

Avalanche activity over the past couple days has mostly been loose wet sluffs from solar radiation and warm alpine temperatures. Earlier in the week there were reports of several large wind slab avalanches throughout the region, some of which resulting in injuries or very close calls. Most of these slides were in response to strong outflow winds.

Snowpack Summary

The current snow surface varies significantly and includes wind affected surfaces in exposed alpine and treeline terrain, a sun crust on steep solar aspects, dry faceted powder in sheltered shady terrain, and pockets of surface hoar (mainly below treeline). Older wind slabs are still lurking on south facing slopes near ridge tops from last weeks outflow winds. The mid-December SH layer may be present in specific areas (sheltered, shady, near open water sources) down 40-70 cm. On Thursday one observer found this layer down 55 cm on a N aspect at 1700 m. Snowpack tests gave easy or moderate "drops" results. Below 2000 m and buried 60-80 cm deep you might find a crust with facets or mixed forms above or below.

Problems

Wind Slabs

An icon showing Wind Slabs
Fresh wind slabs more form on exposed NE-SE facing slopes, while old stubborn hard slabs still linger on South and West facing slopes.
Watch for areas of hard wind slab in steep south-facing alpine features.>Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
There are a couple of persistent weak layers in the top 80 cm of the snowpack, including surface hoar on sheltered shady slopes and a crust/facet layer. These weaknesses could wake up with heavy loading from rain and snow on Sunday/Monday.
Avoid open slopes and steep convex rolls at and below treeline where buried surface hoar may be preserved.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Jan 3rd, 2015 2:00PM

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