Avalanche Forecast

Issued: Jan 29th, 2012 9:39AM

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

ghelgeson, Avalanche Canada

South Rockies.

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

The region is set to receive an additional 15 - 25 cm of dense snow Monday night and the new snow will be at the mercy of strong to extreme winds out of the W. Snow will continue through Monday delivering an additional 10 cm or so before clearing briefly Tuesday. Freezing levels stay relatively high Monday as they top out around 1500m. Another pineapple (warm/moist) system will move into the region Thursday.

Avalanche Summary

Our field team was out in the region Thursday investigating a slide that ran full path. This avalanche path has a SE facing start zone that had been crossloaded by the recent westerly winds. A wind pillow failed high on the slope triggering a size 3 avalanche with a crown as deep as 85 cm. The likely culprit is a crust/facet combo from mid-December. Very little avalanche activity was reported over the weekend, but it's important to note that On Sunday we received a report of a size 2+ avalanche that was likely human triggered on a sparsely treed slope just below steep rocky terrain in the Smith Basin area. This avalanche had a crown of 100 - 150 cm and likely failed on basal facets near the ground.

Snowpack Summary

The freezing level was as high as 1500m Sunday, as a result, a lot of precipitation that fell on Sunday was rain. It's pretty tough to gauge how much snow the region received as a result. Our field team will be out and about Monday, so, we should have a much better idea of just what happened out there soon. Last week 40-60cm of snow formed soft slabs over a crust/facet/surface hoar combo which has settled remarkably quickly.Deeper in the snowpack, a surface hoar layer buried in early December remains a concern, as avalanches triggered on this layer would be destructive. There may have been releases on this layer post storm but at this time nothing has been reported. It should be noted that basal facets exist in many parts of the region too. Facets sandwiched between two firm layers in the top metre of the snowpack are being monitored in the south-east.

Problems

Storm Slabs

Adjacent regions reported sensitive slabs on Sunday, I suspect that it was similair in this region. The area is forecast to reieve another 15 - 25 cm of snow above 1500m Sunday night into Monday.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Wind Slabs

Wind slabs will continue to be an issue Monday as strong to extreme winds work in conjunction with an additional 15 - 25 cm of dense snow. Windslab avalanches as big as size 2.5 are possible on Monday.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Jan 30th, 2012 8:00AM