Avalanche Forecast

Issued: Dec 9th, 2020 4:00PM

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

Avalanche Canada dsaly, Avalanche Canada

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Keep a lookout for any lurking slabs in steep and convex features with dry snow.

Summary

Confidence

Moderate -

Weather Forecast

WEDNESDAY NIGHT: Partly cloudy / Light southeast ridgetop wind / alpine high temperature -3 / Freezing level 1000 m

THURSDAY: Mostly cloudy and isolated flurries / Light southeast ridgetop wind / alpine high temperature -5 / Freezing level 800 m

FRIDAY: Cloudy with sunny breaks or isolated flurries / Light southeast ridgetop wind / alpine high temperature -6 / Freezing level 700 m

SATURDAY: Cloudy with sunny breaks and isolated flurries, 5 cm / Light gusty southeast ridgetop wind / alpine high temperature -3 / Freezing level 600 m

Avalanche Summary

On Tuesday, storm slab avalanches to size 2 were triggered by explosives, and evidence of an overnight natural avalanche cycle to size 2 was reported around Whistler. These dry slab avalanches entrained wet loose debris as they slid and gained mass.

A widespread natural storm slab (size 2-3) and wet avalanche (size 1-2) cycle occurred overnight Mon-Tues in the mountains north of Pemberton.

On Monday afternoon, small size 1 loose and low density slab avalanches failed naturally and with skier traffic as snow began to accumulate and load ridgetops.

Have you been out and about in the mountains? If so please submit to the Mountain Information Network (MIN). It doesn't have to be technical it can be as simple as a photo. Photos are especially helpful! Sending out a big thank you to the already submitted MIN's this season. Thanks everyone!

Snowpack Summary

A melt freeze crust is found to 2000 m, and above 1800-2000 m 20-40 cm of varying moist and dry layers of storm snow accumulated. A 5-10 cm dusting of dry snow covers these features at upper elevations.

Above the rain/snow line the recent storm snow covered older crusts and wind affected surfaces. A new layer of surface hoar reported was reported developing early Wednesday morning. 

Snowpack depths change rapidly with elevation, from 50-100 cm around treeline to over 150 cm in the alpine. Below 1800 m and where rain achieved full saturation, the snowpack is uniform.

The mid to lower snowpack contains a series of crusts, the most notable of which is also the deepest, sitting just above the ground at elevations above 1800 m. This crust may have a thin overlying layer of weak faceted grains and/or surface hoar crystals, especially in sheltered areas around treeline. We have a few reports of these layers being unreactive in tests, with a bit more insight these may little concern going forward. 

Terrain and Travel

  • Be alert to conditions that change with elevation.
  • Caution around convexities or sharp changes in terrain.
  • Carefully evaluate steep lines for wind slabs.

Problems

Storm Slabs

An icon showing Storm Slabs

Storm snow reactivity is quickly decreasing. Keep a look out for lingering slabs around steep rolls and extreme terrain. Cornices might still be a bit touchy.

Aspects: North, North East, East, West, North West.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Dec 10th, 2020 4:00PM