Avalanche Forecast

Issued: Mar 5th, 2017 3:50PM

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

Avalanche Canada mgrist, Avalanche Canada

Storm slabs are very reactive to human triggers. Conservative terrain selection is crucial.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

We're looking at occasional flurries and cool temperatures throughout the forecast period. MONDAY: Cloudy with scattered flurries and up to 3-5 cm of new snow, 30-50 km/h south winds, alpine temperatures around -10 C. TUESDAY: Flurries with 5-10 cm of new snow, 20-40 km/h south winds, alpine temperatures around -11 C. WEDNESDAY: Light flurries, 20-30 km/h south winds, alpine temperatures around -12 C.

Avalanche Summary

On Saturday several storm slabs sized 1.5 to 2.5 (some remote triggered) were reported on north through east aspects, between 1100 and 1400m elevation. On Friday, storm slabs were very reactive to human triggers producing numerous size 1-1.5 avalanches and widespread whumpfing and cracking in flat terrain. Explosive control resulted in numerous size 2-2.5 slab avalanches. A widespread natural cycle occurred during the peak of the storm with up to size 2.5 slabs on a variety of elevations and aspects. Conditions will remain touchy as the recent storm snow settles and stiffens.

Snowpack Summary

Another 5-10cm of low density snow falling Saturday overnight into Sunday has brought recent storm snow totals to 60-85 cm. All this snow has buried a variety of old snow surfaces including surface hoar, facets, crusts, stiff wind slabs and a melt-freeze crust below 1600 m. The storm snow has been very reactive on this interface resulting in widespread whumpfing and cracking in flat terrain, and sudden, propagation-likely test results. Below this interface the snowpack is generally settled and strong with the exception in shallow snowpack areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern.

Problems

Storm Slabs

An icon showing Storm Slabs
Fresh storm slabs are reactive and have a poor bond to the old snow surfaces. Deeper deposits of wind slabs may also exist on leeward slopes and behind terrain features.
Stick to simple terrain or small features with limited consequence.Storm slab avalanches may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 6th, 2017 2:00PM