Avalanche Forecast

Issued: Apr 3rd, 2014 10:36AM

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

Sea To Sky.

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

Avalanches ran naturally to size 2.5 on north facing features Wednesday. Skiers triggered small wind slab avalanches in steep terrain on alpine features too.Correction, the size 2 reported yesterday from a W/SW facing feature at 2300m was not a natural, it was actually remote triggered by a skier from 10m away.

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 15 - 70 cm below the surface, snowpack tests are still producing hard resistant planar shears on the late March crust.The mid March surface hoar/ crust interface now down 80 - 110cm is decreasing in it's sensitivity to triggering.The early-March crust/facet layer is down about 100-150 cm and the early February layer is now down close to 200 cm. These layers are largely dormant at this time.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.

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

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

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