Avalanche Forecast

Issued: Feb 11th, 2012 10:01AM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Cornices.

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Good - -1

Weather Forecast

A ridge of high pressure is expected to rebuild on Sunday over the interior mountains. Moisture that is left over from the weak system on Saturday will continue to cause mid-level cloud and very isolated flurries on Sunday. Winds are expected to continue to be light in the Selkirks and Monashees, and may swing to the east in the afternoon. The freezing level is forecast to rise to about 1200 metres on Sunday and drop overnight to about 800 metres. Treeline maximum temperatures should be about -2.0 on Sunday and Monday. A weak Pacific system is expected to run into the ridge of high pressure on Monday that should cause some localised flurries in the western areas of the region. The wind should change to northwest on Monday night as more high pressure moves across the interior. Temperatures should drop down to about -15.0 in the alpine briefly on Tuesday morning. Clear skies and strong solar radiation is expected during the day on Tuesday, however northwest winds should help to keep alpine maximum temperatures close to -10.0 on shaded aspects.

Avalanche Summary

Some minor sloughing in steep terrain on northerly aspects continues to be reported.

Snowpack Summary

Most areas have a thin layer of new snow above buried surface hoar. Some areas have reported a very light freezing drizzle that has mixed with some rimed stellars to form a thin soft crust above the recently buried surface hoar layer(120208 SH). Warm alpine temperatures and solar radiation have developed a melt-freeze crust on southerly aspects in the alpine and on all aspects below about 1300 metres. There are a couple of layers that are buried between 25-35 cm that give resistant planar results from tests when hard forces are applied. Recent facetting in the top 20 cm appears to rounding and bonding. The mid pack is generally well settled and well bonded. Deeper weaknesses in the snowpack are less of a concern; however, in the southern end of the region there is still talk of basal facets as some operators are avoiding thin and rocky alpine features. This represents a very low probability-high consequence scenario. Large cornices are also widespread in the alpine.

Problems

Cornices

An icon showing Cornices
Large and unsupported cornices exist in the alpine. Failing cornices are destructive by themselves and have potential to trigger avalanches on the slope below.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 6

Valid until: Feb 12th, 2012 3:00AM