Avalanche Forecast

Issued: Jan 2nd, 2019 6:10PM

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

Avalanche Canada shorton, Avalanche Canada

An intense storm will bring heavy snowfall, rain, and wind to the region on Thursday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

WEDNESDAY NIGHT: 10-30 cm of snow, freezing level climbing to 1800 m in the southern part of the region and 1500 m in northern parts, strong to extreme wind from the southwest.THURSDAY: Huge variability in snow forecasts, but 15-40 cm possible in northern parts of the region and 30-60 cm possible in southern parts of the region, freezing level dropping throughout the day to 1200 m by the evening, extreme wind from the southwest.FRIDAY: Another 10-30 cm of snow, freezing level steady around 1200 m, strong wind from the southwest.SATURDAY: Cloudy with some sunny breaks, light wind, alpine high temperatures around -5 C in the north and 0 C in the south.

Avalanche Summary

A few small storm slab avalanches were reported on Wednesday. Several skier and snowmobile triggered avalanches were reported on Sunday. There was a report of two skier triggered avalanches in the Zoa peak area near Coquihalla Summit. These were both reported to be up to size 2 and running on a layer of surface hoar buried 40-60 cm deep on a north aspect at treeline. See the MIN report here. An additional avalanche incident was reported by snowshoers in Manning Park. It is suspected to have run on the same weak layer. See the MIN report here.

Snowpack Summary

Storm snow will rapidly accumulate on Thursday, with 40-80 cm of fresh snow possible by the afternoon in southern parts of the region and 30-60 cm in northern parts. Rising then dropping freezing level will create an interesting mix of rain and snow at treeline and below treeline elevations.A weak layer composed of surface hoar that was buried on December 26 can be found at treeline elevations 20-50 cm below the new storm snow. This layer is reported to be most prevalent at the upper end of treeline on north and east aspects in the southern part of the region (e.g. Coquihalla Summit and Manning Park). This layer has been reactive recently and will definitely be reactive during the storm.In the north part of the region, another weak layer composed of facets and/or surface hoar is buried 100 to 150 cm deep at treeline (up to 2000 m), and may be reactive during the storm.

Problems

Storm Slabs

An icon showing Storm Slabs
Heavy snowfall, extreme wind, and rising freezing levels will form fresh storm slabs. Older storm snow may still be reactive at treeline elevations around Coquihalla Summit and Manning Park too.
Minimize overhead exposure during periods of heavy loading from new snow, wind, and rain.Storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

1.5 - 3

Loose Wet

An icon showing Loose Wet
Heavy rain falling on fresh snow will create loose wet avalanches too.
Use extra caution on solar slopes or if the snow is moist or wet.Loose wet avalanches can occur in steep trees.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Very Likely

Expected Size

1 - 1.5

Valid until: Jan 3rd, 2019 2:00PM

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