Avalanche Forecast

Issued: Feb 15th, 2019 4:30PM

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

Avalanche Canada mconlan, Avalanche Canada

The first half of the storm was a bit of a bust, but Friday night's wave could be strong. Snowfall amounts are uncertain and may be spatially variable in the region. The forecast herein assumes 30+ cm of snow accumulation.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

FRIDAY NIGHT: Cloudy with snowfall, variable accumulation in the region between 5 and 20 cm, moderate west wind, alpine temperature -8 C.SATURDAY: Cloudy with snowfall, accumulation 5 to 15 cm, light to moderate west wind, alpine temperature -13 C.SUNDAY: Mostly cloudy with light snowfall, accumulation 5 cm, light north wind, alpine temperature -20 C.MONDAY: Mostly clear skies, light north wind, alpine temperature -18 C.

Avalanche Summary

On Thursday, there was further evidence of a natural avalanche cycle that occurred on Wednesday, with many large (size 2 to 3) storm slab avalanches observed. The avalanches were generally 20 to 40 cm deep, on northerly aspects, and within all elevation bands. There were also indications of instability within one of the buried weak layers described in the Snowpack Summary, as noted here.

Snowpack Summary

More snowfall is expected Friday night into Saturday, with total amounts uncertain but could be upwards of 20 cm or more. This new snow overlies around 30 to 50 cm of recent storm snow, which may have been redistributed by strong northeast wind at higher elevations.Two weak layers may be found within the snowpack. A weak layer of surface hoar crystals that was buried early-February may be found about 50 cm deep in shaded and sheltered areas above 1600 m. The mid-January layer of surface hoar is buried around 70 cm and is most prominent between 1600 m and 1900 m.The remainder of the snowpack is well-settled. Thin snowpack areas, such as in the far east of the region, may find weak and sugary faceted grains near the base of the snowpack.

Problems

Storm Slabs

An icon showing Storm Slabs
More snow is forecast, with high uncertainty in amounts. It could be 10 cm or 30+ cm by Saturday. Avoiding avalanche terrain is the prudent choice if more than 30 cm accumulates. If triggered, avalanches could step down to deeper weak layers.
If triggered, storm slabs may step down to deeper layers resulting in very large avalanches.A good day to avoid avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
All this recent storm snow is rapidly loading weak surface hoar crystals. The layer is likely best preserved in shaded and sheltered areas between 1600 m and 1900 m and could be associated with a melt-freeze crust on south aspects.
A good day to avoid avalanche terrain.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3.5

Valid until: Feb 16th, 2019 2:00PM

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