Avalanche Forecast

Issued: Mar 1st, 2018 3:08PM

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

Avalanche Canada istorm, Avalanche Canada

The riding is great and avalanche conditions are pretty good. Use normal caution, safe travel techniques and keep an eye on the sun -- sunny southerly slopes seem the most complicated!

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

A weak front is stalling on a north to south axis over the region setting up a southerly wind with most snow expected in the southern parts of the region.Friday: The important part of the weather forecast is new snow and wind overnight Thursday: only up to 10cm new snow is expected but moderate south or southeast winds will blow it around. Calmer and drier through the day. Temperatures staying on the negative side of zero. Mix of sun and cloud, most sun in the north.Saturday:  Mix of sun and cloud (sunnier in north, cloudier in south) but dry with only flurries. Little wind at all elevations and temperatures at treeline staying around or below -5 C.Sunday: Compared to Saturday, Sunday looks very similar:  maybe a little bit sunnier and continued dry. It might be a bit windier (light from the SW), and similar temperatures.

Avalanche Summary

Wednesday reports either spoke to "no new avalanches" or small (size 1 to 2) slabs triggered by people. There was a single size 2.5 avalanche on a south aspect releasing on a layer approximately 70 cm deep.Prior to Wednesday, avalanche activity consisted of mainly loose dry sluffing, storm slabs, or wind slabs (skier triggered and skier remote) in the size 1to 2 range. However, we've received reports of persistent slab avalanches where recent accumulations have been the highest. These avalanches, were remotely triggered (from a distance) or naturally occurring. We suspect the sun crust buried mid-February is the culprit for those on southerly aspects. Deep persistent avalanche activity has become less frequent over the past week.

Snowpack Summary

The 30 to 50cm of recent storm snow is "right side up" and settling. Earlier in the last storm it was redistributed into localized wind slabs. It covers old surfaces including faceted powder, a sun crust on solar aspects, and surface hoar on shady slopes. Around 50 to 80cm below the surface there's a layer buried mid-February that's a sun crust on solar aspects and spotty surface hoar on sheltered slopes. This layer looks most concerning on solar aspects where it's associated with with small facets or surface hoar. March 01 today -- 'tis the season when solar aspects start to get complicated!There are several deeper layers that have shown signs of improving but still remain suspect as low probability - high consequence avalanche problems. I'm talking about surface hoar layer buried back in December and January. Near the base of the snowpack is a November crust combined with loose sugary snow. These layers may "wake-up" with strong inputs such as sustained warming, sustained snowfall, large triggers (e.g. cornice fall, smaller avalanches coming down from above); human triggering is also possible in shallow, rocky terrain.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm slabs are most likely found in sheltered areas on steeper slopes and rolls. Localized wind slabs may have formed on the down-wind side of ridges and ribs. Watch cross-loaded slopes and gullies too!
Use caution on open slopes and convex rolls Stay off recent wind loaded areas until the slope has had a chance to stabilize.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
An interface buried up to 70cm deep has "woken-up". This problem seems most reactive in south-facing terrain where buried crusts exist.
Carefully assess and consider avoiding southerly facing slopes.Pay attention to overhead hazards like cornices which could trigger persistent slabs.Watch convoluted terrain with variable or shallow snow depths and multiple trigger points.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Mar 2nd, 2018 2:00PM

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