Avalanche Forecast

Issued: Mar 15th, 2013 11:07AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Loose Wet.

ghelgeson, Avalanche Canada

South Coast.

Uncertainty exists with forecast freezing levels and the bond within and below the recent storm snow, especially across different elevation bands. Be alert to conditions that change with elevation and make observations continuously as you travel.

Summary

Confidence

Poor - Due to variable snowpack conditions

Weather Forecast

Synopsis: The pattern calms down a bit as the flow becomes more zonal (westerly). A few weak features impact the coast through the weekend.Saturday: Freezing Level: 1200m Precip: 3-6mm/4-12cm Wind: SW Moderate gusting Strong.Sunday: Freezing Level: Surface Precip: Trace Wind: NW, Moderate.Monday: Freezing Level: 1200m Precip: Trace Wind: SW, Moderate

Avalanche Summary

Numerous size 2.5 - 3.0 avalanches are being reported from the Coquihalla where there hasn't been an overnight refreeze in days.

Snowpack Summary

The storm has delivered around 60 cm of heavy snow at upper elevations while simultaneously raining as high as 1900m as freezing levels fluctuated during the storm. Below 1500m the snowpack was reported to be isothermal as of Friday afternoon. The new snow has been settling rapidly and is slowly bonding to the previous snow surface, which includes faceted snow, surface hoar, and/or a crust. This interface is most concerning where the surface hoar is sitting on a crust on previously sun-exposed slopes. Cool temperatures should slow natural avalanche activity in the coming days but I suspect the snowpack could still use a bit of time to adjust to it's new load. We also need to gather more information on this interface before we think getting into the bigger terrain. The mid-pack is strong and well settled, although the entire snowpack will remain volatile below 1500m until it has a chance to freeze.

Problems

Storm Slabs

There's a lot of uncertainty surrounding the new/old snow interface which consists of surface hoar, old wind slabs and crust. We need to gain more information on this interface before we start thinking about bigger objectives.

Avoid large alpine features>Avoid freshly wind loaded features.>Avoid open slopes and convex rolls where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 6

Loose Wet

Slopes below 1500m are unlikely to refreeze Friday night. As a result large wet loose snow avalanches will likely continue to run naturally Saturday.

Avoid all avalanche terrain below treeline until it has a chance to properly refreeze.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Valid until: Mar 16th, 2013 2:00PM