Avalanche Forecast

Issued: Mar 11th, 2013 3:00PM

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

Avalanche Canada pmarshall, Avalanche Canada

The avalanche danger will rise throughout the day on Tuesday as snow accumulates, winds increase, and the freezing level rises.

Summary

Confidence

Fair - Timing of incoming weather is uncertain for the entire period

Weather Forecast

Synopsis: A steady southwest flow will drive a series of disturbances onto the south coast this week. There is some uncertainty regarding the timing of each pulse of heavy precipitation, but it’s fairly certain to be a wet and mild week. Overnight and Tuesday: Moderate to heavy precipitation – 25-40 cm. The freezing level will rise to around 1600 m by Tuesday afternoon. Winds are strong from the south-southwest. Wednesday: Moderate to heavy precipitation – 20-30 cm. The freezing level climbs to 1800 m. Winds remain strong from the south-southwest.  Thursday: Moderate to heavy precipitation continues. The freezing level starts near 1600 m but could drop later in the day or by Friday morning.  

Avalanche Summary

Avalanche activity on Sunday was limited to small loose wet sluffs on steep sun exposed slopes. A few size 1 wind slabs were also reported on Saturday in response to strong southwest winds.

Snowpack Summary

Dribs and drabs of recent snowfall have been shifted by strong southwest winds into touchy new windslabs in exposed areas. In more sheltered terrain, surface hoar and/or surface facets are likely to exist. A sun crust has formed on south facing terrain.Between 60 and 110cm below the surface is a layer surface hoar which was buried on February 20th. Although this layer has a history of producing large avalanches, triggering this layer has now become difficult, and would most likely require a very large trigger on a steep, unsupported slope. Below this interface, the snowpack is strong and well settled.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow may not bond well to the previous surface, which includes a sun crust, surface hoar, and old sugary snow. Weak wind slabs will likely form in exposed North through East aspects and cross-loaded gullies and may release naturally.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be cautious as you transition into wind affected terrain.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Mar 12th, 2013 2:00PM