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Avalanche Forecast

Apr 8th, 2012–Apr 9th, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: South Columbia.

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

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.

Avalanche 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