Avalanche Forecast

Issued: Mar 8th, 2016 7:21AM

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.

mike.koppang, Alberta Parks

Kananaskis.

The weekend warm up is over and cooler temperatures now prevail. Our #1 concern remains the January 6th facet layer interface, it is a tough layer to trigger but will produce big avalanches out of steep rocky, shallow snowpack areas in the alpine.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

Cloudy with sunny periods and isolated flurries with trace snow accumulation. Alpine temperature -6.0. Winds will be westerly 25km/h with gusts to 60km/h in advance of a front that is due to arrive overnight Wednesday. Freezing level will be valley bottom (1400 meters).

Avalanche Summary

As alluded to there were several avalanches on the January 6th facet interface. One size 2.5 by some skiers heading up to the brand new Des Poilus Hut over in the Yoho Park. Another size 2.5 near the Bow Summit area and today Parks Canada reported a solid size 2.5 out of Eagle 3 path at the Sunshine Ski Area. The common thread with all of these avalanche events is that the start zones were in shallow snowpack areas.

Snowpack Summary

The snowpack had taken on some significant warming over the weekend with high freezing levels in addition to rain at lower treeline elevations. This moist snow has transformed into yet another melt freeze crust that was buried yesterday evening March 8th. The storm ended last night and deposited anywhere from 4-15cm of low density snow over this newly buried crust - the bond on this new snow to the crust appears to be pretty strong from what we saw. The new crust ends at about 2250 meters and the ski quality improves profoundly above this elevation. The crusts from Feb 27th are buried 35-45cm deep and the Feb 11th layer is down anywhere from 50-80cm deep. The January 6th layer is the one that concerns us the most - it is approximately 80-100cm deep in the alpine and it is still producing anywhere from moderate to hard sudden collapses and also no results in some test pits indicating high variability. There has been steady avalanche activity on this layer in the Rockies and although it is a hard layer to trigger - it is regularly producing monster avalanches size 2.5-3.0.

Problems

Wind Slabs

Watch for thin soft slabs on the steep transitions slopes below head wall features and also at or near ridge top features, especially in steep start zones.

Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Shallow snowpack areas at ridge top where the winds have scoured thin to thick snowpack depths are to be avoided - it is possible to trigger very large, full depth avalanches on the January 6th facets.

Avoid steep slopes below cornices.>Avoid convexities or areas with a thin or variable snowpack.>Carefully evaluate and use caution around thin snowpack areas.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Mar 9th, 2016 2:00PM