Avalanche Forecast

Issued: Apr 3rd, 2014 10:41AM

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

ghelgeson, Avalanche Canada

South Coast.

This forecast is based on less than 10cm of new snow Thursday night and Friday. If snow totals unexpectedly reach 15 to 20 cm, the new slab will likely be touchy, and the danger considerable at all elevations.

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather system is uncertain on Friday

Weather Forecast

Synopsis: The front and the associated upper trough move through the coast Thursday night. Onshore flows in the wake of the front aren't expected to deliver more than trace amounts Friday. The story is the same though the weekend, small amounts of precipitation accompanied by moderate winds. Looks like potential for a big warm up Monday.Thursday Night: Precipitation: 3:8mm - 4:15cmFriday: Freezing Level: 1000m - 1800m; Precipitation: 1:3mm - 1:5cm; Wind: Treeline: Moderate, SW | Ridgetop: Strong, SWSaturday: Freezing Level: 1200m - 1800m; Precipitation: 1:8mm - 1:10cm; Wind: Treeline: Moderate, SW | Ridgetop: Strong, SWSunday: Freezing Level: 1200m - 1900m; Precipitation: Trace; Wind: Treeline: Light, Variable | Ridgetop: Moderate, NW

Avalanche Summary

Cornice fall on a steep north facing features at 2300m initiated a size 3 avalanche Wednesday. This likely ran on the early March melt-freeze crust. Small soft wind slabs immediately lee of ridge crest were easily managed by skiers.In the neighboring Sea to Sky region warming temps induced cornice fall Tuesday. A notable event occurred on a NE facing slope at 2100m when a falling chunk of cornice triggered a small slab immediately below the ridge. The avalanche in motion stepped down to what was likely the late March crust resulting in a size 2.5 avalanche.

Snowpack Summary

The snow surface is a mix of surface hoar, small grained facets and melt freeze crusts.Recent warm temperatures have helped to settle and strengthen the upper snowpack. Down 30 - 50 cm below the surface, snowpack tests are still producing hard resistant planar shears on the late March crust.The persistent weak layers from early March and early February continue to be a concern. The March melt-freeze crust/surface hoar is reported to be down 60 - 100cm. The February crust/facet/surface hoar layer is now deeply buried down 150 - 250cm.The lower snowpack is strong and well settled.

Problems

Storm Slabs

Small amounts of new snow driven by strong SW wind is unlikely to bond well to the current snow surface. Watch for increasingly sensitive storm slabs lee of both ridge crest and mid slope features like ribs/rock outcroppings.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

Three buried weak layers exist in the snowpack. These weak layers could be activated by cornice fall, a smaller surface avalanche in motion, or a rider finding the sweet spot, which would be most likely in steep rocky terrain.

Be aware of the potential for large, deep avalanches due to the presence of buried facets and surface hoar.>Extra caution needed around cornices with current conditions.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 4th, 2014 2:00PM