Avalanche Forecast

Issued: Nov 23rd, 2012 8:56AM

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

Overnight and Saturday: Expect another 3-8 mm of precipitation before the cold front moves through the region. 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. No precipitation is expected.Monday: Continued High pressure.

Avalanche Summary

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

Snowpack Summary

No reports of the surface hoar that I suspected yesterday. New snow continues to add to the load above weak layers. The November crust may become reactive from the additional load of the storm and wind transported snow. 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. 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 1200 metres during the recent storm, and the snow line has been creeping down towards the valleys. Snow levels taper off to below threshold by about 1000 metres. There is about 80-110 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

Storm slabs continue to build as the storm moves through the region. Moderate to strong SW winds have developed wind slabs in the alpine on North through East aspects. The young snowpack may need a couple of days to settle and bond to the old surface

Avoid freshly wind loaded features.>Be cautious of buried obstacles in shallow snowpack areas.>

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.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Nov 24th, 2012 2:00PM