Avalanche Forecast

Issued: Nov 22nd, 2012 9:07AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Storm Slabs and Persistent Slabs.

triley, Avalanche Canada

South Columbia.

This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the forecasters blog for further details on interpreting early season bulletins.

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Thursday Overnight: Increasing cloud with 0-3 mm precipitation. Freezing level at about 900 metres. Warmer in the South, but generally -4.0 in the alpine. Winds light from the SW.Friday: Cloudy with 4-7 mm precipitation, maybe a bit more in the North and the western upslope areas. Freezing level rising to about 1300 metres during the precipitation and then descending to near valley bottoms, -4.0 in the alpine. Winds increasing to SW 40 km/hr.Saturday: Cooling trend behind the storm as High pressure moves into the region, freezing level at valley bottoms. Expect -9.0 in the alpine. Winds should clock to the NW and decrease to about 20 km/hr.Sunday: Should still be under the influence of the High pressure. Cooler temps and light winds.

Avalanche Summary

No new reports of avalanches. If you any observations please share here.

Snowpack Summary

I suspect that there might have been some surface hoar growth Thursday morning due to overnight clear skies. If you have any observations, please share by email. The recent storm snow has been wind affected in the alpine and open areas at treeline. Some people are reporting a thin crust on solar exposed aspects that developed late last week (November 17th), and is now buried by the new storm. The freezing level went up to about 1500 metres during the recent storm. Snow levels taper off to below threshold by about 1200 metres. There is about 60-80 cms of recent storm snow above an early November crust, or series of laminated crusts. Tests have been showing easy to moderate SP (sudden planar) pops on weak facetted crystals at this crust interface, or within the crust sandwich.

Problems

Storm Slabs

Storms slabs are expected to continue to build during the day on Friday. Increasing SW winds in the afternoon may start build wind slabs in the alpine on North through East aspects.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Persistent Slabs

There is a variable crust in the alpine that developed during a high rain event in early November. This crust only exists where there was enough snow at that time. This may become reactive with a new storm load.

Choose well supported terrain without convexities.>Plan escape routes and identify safe zones before committing to your line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Nov 23rd, 2012 2:00PM