Archived

Avalanche Forecast

Mar 28th, 2015–Mar 29th, 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

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Coast.

Unusual persistent slabs continue to produce very large human triggered avalanches. See the latest forecaster blog for a more in depth look at this situation: http://bit.ly/1HHQrK2

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

A series of wet storms are set to impact the coast until Tuesday morning then a cooling trend. Saturday night: 5-10 mm precip can be expected between 4pm Saturday and 4am Sunday with freezing levels around 1700 m and strong southwesterly winds. Sunday: A further 10-20 mm precip is expected with freezing levels around 1900 m and southwest ridgetop winds gusting to 60 km/h. Monday: Another pulse looks to bring 10-15 mm precip with freezing levels around 1900 m and southwest ridgetop winds gusting to 60 km/h. Tuesday: Possibility of lingering storms that could bring highly variable precipitation. A cooling trend is expected to lower freezing levels to around 1000 m. Winds are expected to diminish.

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

This region has a very serious persistent slab problem that exists under the upper layers of dense storm snow. Depending on how much recent snow has fallen, a facet/crust persistent weak layer buried mid-March lies anywhere from 40-120 cm below the surface. Avalanches have continued to run on this layer at upper treeline and alpine elevations, especially in the north of the region. Snowpack layers deeper than this critical interface are reported to be generally well-settled and strong.

Avalanche Problems

Persistent Slabs

There is significant danger that the touchy persistent slab buried an average of 80 cm below the surface will become overloaded by new rain and snow. The depth of this layer could result in some large and destructive avalanches.

Remote triggering is a concern, watch out for adjacent slopes.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 3 - 6

Storm Slabs

Forecast new snow (above around 1800 m) and strong winds will set up storm slabs in steep terrain at higher elevations.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4