Avalanche Forecast

Issued: Nov 25th, 2012 9:40AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

slemieux, Avalanche Canada

South Rockies.

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

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

The sunnier drier ridge bringing cooler temperatures at night and mild afternoon temperatures with low winds from the North West is forecasted to last until Wednesday. Increased cloud cover starting to build Tuesday or Wednesday, a sign that the next system is approaching the region. There is not much confidence in the timing of the arrival of the next system, but it looks like it should not effect the conditions covered by this bulletin. Watch for the weather update in the days to come.

Avalanche Summary

There has been a couple second hand reports of large whumphing in the Harvey pass area and triggering a large size avalanche that could have run on the lower November crust. If you and your friends have been out exploring and riding in the backcountry, and have some observations to share please send us an email to forecaster@avalanche.ca.

Snowpack Summary

The 15 to 30 cm of storm snow that was very reactive yesterday and created up to size 2 natural avalanche in the Lizard range should be in process of settling. However, the afternoon mild temperatures with the sun shining could weaken temporarily the storm slab and the windslabs. The November crust is now below 100 cm in the Alpine and is apparently still active and producing clean shears when tested. This persistent weak layer seems to be found mostly found above 1800m on slopes with smooth ground cover. Below treeline snow levels may just be reaching threshold. If you are traveling in this elevation band, be mindful of obstacles like rocks and trees that could be hiding under a thin layer of snow.

Problems

Wind Slabs

Wind slab instabilities exist mostly on N and NE aspects may be touchy to rider triggers. Storm slab instabilities may still exist on all aspects and could weaken if solar intensity is high.

Avoid cross loaded slopes at or above treeline.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

The early Nov. crust is buried down approximately 100 cm of snow near the base of the snowpack and is still reactive in areas with smooth ground cover, like grassy slopes. An avalanche initiated in the recent snow could step down to this layer.

Be aware of thin areas that may propagate to deeper instabilites.>If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Nov 26th, 2012 2:00PM