Avalanche Forecast

Issued: Apr 13th, 2012 11:08AM

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

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

A ridge of high pressure is expected to slowly move into the interior ranges on Saturday. Unsettled conditions with showers in the valleys and flurries above 1700 metres should continue during the day. Clearing skies are forecast by Saturday evening, which should bring the freezing level down to about 1200 metres overnight. Sunday should be mostly sunny with light variable winds and a chance of afternoon cloud building as the freezing level rises to about 1800 metres. The wind is expected to start to build out of the southwest on Monday as a low pressure system moves onto the south coast. It is a little too early to forecast when this system will push into the eastern ranges of the interior mountains.

Avalanche Summary

No new avalanche observation reported.

Snowpack Summary

On Thursday, up to 10 cm of new snow fell at upper elevations. This recent spring- like warm weather has promoted settlement within the snowpack. Melt-freeze conditions exist, and snow is moist below 1700 m on all aspects. On solar aspects the snow has become moist to ridgetop and new snow may have a poor bond to the crust. Below the surface, down 60-100 cm sits on the March 27th interface which seems to be more predominant on southerly aspects. The bond on this interface seems to be improving, as field tests have shown no significant results. On Tuesday our field team went back to the Flathead to gather some observations. They found the mid Feb surface hoar layer down 280 cm, test results showed a Deep Tap Test of 21 with a sudden collapse characteristic. This layer currently sits dormant, but may wake up later this spring under a prolonged heat up.

Problems

Loose Wet

An icon showing Loose Wet
Moist or wet loose snow avalanches may release during periods of daytime warming or if periods of rain showers persist. Loose snow avalanches may trigger deeper weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Wet Slabs

An icon showing Wet Slabs
Large triggers like cornices or loose snow avalanches may propagate slide on the buries weak layer from March 27th. The likelihood may increase if there is no overnight freeze.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Persistent Slabs

An icon showing Persistent Slabs
Strong solar radiation or persistent warm temperatures may trigger deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 14th, 2012 9:00AM

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