Avalanche Forecast

Issued: Apr 8th, 2012 10:45AM

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

jfloyer, Avalanche Canada

South Columbia.

Spring conditions means you should anticipate a daily cycle of loose snow avalanches on south-facing slopes.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

This region should remain dry from Monday through Wednesday. Freezing levels will be around 2000 m on Monday, with sunshine through high cloud. On Tuesday, freezing levels will go to around 2800 m and on Wednesday as high as 3000 m. Winds are expected to be light southeasterly throughout the period.

Avalanche Summary

On Saturday a large (size 3) naturally-triggered avalanche released on a southwest aspect at 2300 m. The avalanche initiated in a shallow rocky start zone and initially pulled out the recent storm snow before stepping down to lower layers, in some places scouring all the way to ground. Another large (size 2.5) avalanche occurred on a northwest aspect at 2300 m and ran all the way to ground.

Snowpack Summary

40-80 cm of recent storm snow is sitting on a reactive weak layer over a crust. This weak layer was buried March 27th in the Interior. Initially, we had many reports of large, destructive avalanches occurring on this layer, although the frequency of these events has been diminishing. However, this layer still needs to be closely monitored, especially since the crust could help channel moisture produced by the warm spring-time temperatures. There is a good chance that wet slabs could release on the crust during prolonged periods of warm temperatures and/or sunshine. Lower elevation slopes continue to experience little or no overnight refreeze (recovery). The deeper early February surface hoar layers have been unreactive recently but still remain a concern with prolonged spring warming and very heavy triggers such as a cornice fall, or step down avalanches.

Problems

Loose Wet

Expect loose snow avalanches to occur on steep south-facing terrain in the afternoon, or by late morning if the sun is strong.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Wet Slabs

With prolonged warm temperatures, wet slabs become more likely on a crust buried 50-80 cm.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 5

Deep Persistent Slabs

While still unlikely, a couple of recent events indicate deeply buried weak layers have the potential to wake up and produce large avalanches during periods of prolonged warming or from heavy triggers such as cornices or step-down avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

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