Avalanche Forecast

Issued: Apr 6th, 2012 4:00PM

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

ghelgeson, Avalanche Canada

South Rockies.

Summary

Confidence

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

Weather Forecast

A trough exits to the east Saturday as high pressure builds into the region in the afternoon. Clouds persist through most of the day, but the occasional sunny break is expected. Freezing level rises to 1800 m in the afternoon. Sunday: Sunny skies allow freezing levels to climb to 2000 m. Winds calm, increasing to light out of the E in the afternoon. Monday: Freezing levels spike to 2500 under sunny skies. Treeline winds remain calm/light, ridge top winds moderate SW.

Avalanche Summary

No recent avalanche observations from the region. Control work in the Fernie area Thursday produced avalanches to size 2 with most activity being limited to the 20 cm of storm snow. The storm snow was reportedly quite sensitive to ski cutting, numerous size 1.5 avalanches were triggered in this fashion on N, NE & E facing slopes. A few deeper avalanches were triggered by control work under headwall features too.

Snowpack Summary

The region picked up 20 cm from Wednesdays storm which came to rest on the April 4th melt/freeze crust. An exiting upper trough likely shielded the region from much solar input Friday. Recent storm snow has added up to 60-120 cm depending on the drainage. The storm snow has been failing on a crust on southerly aspects that may have small facets or surface hoar at the interface. High freezing levels and solar radiation have caused wet loose snow avalanches. Large cornices loom over many lee slopes.

Problems

Storm Slabs

The odd deep slab could still be out there, I'm still suspect of steeper unsupported slopes & places where the snowpack goes from thick to thin, especially near ridge crest and around rock outcroppings.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Cornices

Cornices have grown large & unruly. Cornices receiving direct sun will eventually grow weak & there is potential for cornice fall to initiate deep persistent slab avalanches on underlying slopes. Pay attention to what's happening above you.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

3 - 7

Loose Wet

Periods of sun are expected Saturday & the new snow will likely react to the strong solar input, producing loose snow avalanches, with the potential for deeper slab avalanches on slopes that bake all day under the strong spring sun.

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Apr 7th, 2012 9:00AM