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Archived

Avalanche Forecast

Mar 25th, 2015–Mar 26th, 2015
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: South Coast.

Warming temperatures will likely increase the probability of large human triggered avalanches.  See the latest forecaster blog for more information on this atypical coast mountain snowpack: http://bit.ly/1HHQrK2

Confidence

Poor

Weather Forecast

Thursday:  No significant precipitation expected.  Moderate SW winds at treeline, strong W/SW winds at ridgetop.  Freezing level starting the day at 2500m, climbing to around 2700m by Thursday night.Friday: No significant precipitation.  Freezing level starting around 2700m, lowering slightly to 2200m in the evening.  Moderate to Strong SW winds at all elevations.Saturday: Freezing level starting at a more seasonal 1500m, rising to 1800m in the afternoon.  Scattered convective flurries with no significant accumulations expected.  Moderate W/SW winds at treeline, Strong ridgetop winds out of the NW in the morning switching to SW in the afternoon.

Avalanche Summary

Over the past week, there have been a number of avalanches to size 2.5 occurring on the mid-March persistent weak layer. Some avalanches have occurred naturally and many have been remote triggered from up to 100m away.

Snowpack Summary

5 to 20 cm of light storm snow fell in the last 48 hours.  This snow rests on top of ageing wind slabs that formed over the last week in response to recent wind, snowfall and warm temperatures. At lower elevations, rain has saturated the snowpack. Cornices may also be fragile. A touchy crust/facet interface known as the mid-March persistent weak layer is 40 to 120 cm below the surface.  This persistent weak layer continues to produce sudden test results at upper treeline and alpine elevations, especially in the north of the region.  Below this, the snowpack is reported to be generally well-settled and strong.

Avalanche Problems

Persistent Slabs

Sudden failures in snowpack tests and recent large avalanches show that the mid-March persistent weak layer commands respect. Warming temperatures will likely increase the reactivity of this slab Friday.
Stick to simple terrain and be aware of what is above you at all times. Cornice fall will become more likely with warming temperatures.>Remote triggering is a concern, watch out for adjacent slopes.>Avoid steep high consequence features, convexities and areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 3 - 5