Avalanche Forecast

Issued: Mar 24th, 2015 9:47AM

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

Avalanche Canada ghelgeson, Avalanche Canada

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Sea To Sky.

The region has a potentially volatile snowpack structure which although atypical for this time of year, continues to produce very large human triggered avalanches.

Summary

Confidence

Fair - Freezing levels are uncertain on Wednesday

Weather Forecast

Wednesday:  Light snow turning to rain as freezing levels begin to climb.  The freezing level should be around 2500m by sundown.  Moderate SW winds at treeline, strong to extreme SW winds at ridgetop.Thursday:  Light rain.  Freezing level starting around 2400m, rising to approximately 2800m by sundown.  Light SW winds at treeline, strong SW winds at ridgetop.Friday: Light rain.  Freezing level starting around 2500m, lowering to 2000m by dinner time.  Moderate SW winds at treeline, strong SW winds at ridgetop.

Avalanche Summary

Over the past week, very large slab avalanches have been running to size 3, failing on the mid-March persistent weak layer.  This interface remains very reactive, avalanches have been remote triggered by skiers as recently as Monday.  See this observation for a good visual: http://bit.ly/1CS2Nld

Snowpack Summary

A few cm of fresh snow fell with almost no wind Monday night.  This recent dusting should make for great riding, but the region has a very serious persistent slab problem just under the surface.  A cohesive slab 40 to 120cm in depth rests on the mid-March persistent weak layer that consists of small grain facets on a crust.  This interface has been quite volatile recently and remains sensitive to human triggering.  At lower elevations, rain has saturated the snowpack.  The mid and lower snowpack are generally well-settled and strong.

Problems

Persistent Slabs

An icon showing Persistent Slabs
It's nearly impossible to say which pieces of terrain are capable of producing very large avalanches and which are not.  Warming temps Wednesday are expected to increase the reactivity of this slab making it more tricky to manage.
Start and finish early before temperatures get too warm.>Avoid steep high consequence terrain, convexities and areas with a thin and/or variable snowpack.>Stick to simple terrain and be aware of what is above you at all times. Cornice fall will become more likely in the afternoon.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 5

Valid until: Mar 25th, 2015 2:00PM

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