Avalanche Forecast

Issued: Jan 24th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Continued snowfall with consistently strong southwesterly winds will maintain elevated avalanche danger Saturday. If 24 hour new snow amounts exceed 20 cm, increase the danger to high for exposed treeline and alpine areas.

Summary

Confidence

Moderate - Forecast precipitation (either snow or rain) amounts are uncertain.

Weather Forecast

Friday night: 5 -15 cm new snow. Strong southwesterly winds. Freezing level around 1000 m.

Saturday: 5-10 cm near Terrace, 30-40 cm near Kitimat. Strong southwesterly winds. Freezing level around 1000 m.

Sunday: 5-10 cm new snow. Moderate southwesterly winds. Freezing level around 800 m.

Monday: 10-15 cm near Terrace, 20-30 cm near Kitimat. Moderate southwesterly winds. Freezing level around 500 m.

Avalanche Summary

On Thursday, numerous loose wet avalanches to size 1.5 were observed in steep features below 700 m. Several natural and skier triggered storm slab avalanches up to size 1 were reported at treeline elevations. Few alpine observations due to limited visibility, but a few reports of natural wind slab avalanches up to size 2.5.

Reports of deep persistent slab avalanches have been trickling in throughout the month, with the last reported event occurring on Jan 17th. They are associated with a November crust layer near the base of the snowpack which has produced very large avalanches (size 3+) with crown depths of around 2 m. These have typically run in alpine terrain, on lee or cross-loaded slopes. Recent loading has been a good test for this layer and it seems to be trending less reactive.

Snowpack Summary

Around 1 m of recent storm snow is settling rapidly with mild weather, with moist surface snow below 1400 m. In exposed areas above 1400 m, expect southerly winds to build fresh wind slabs on north facing slopes. The new snow rests on extensively wind affected surfaces at upper elevations, and a thick layer of weak facets in sheltered areas treeline and below.

A deep crust from mid November lurks at the base of the snowpack. Although the last reported avalanche on this layer was from Jan 17th, I wouldn't write this layer off. At this time it is most likely to react in response to a large trigger such as a cornice fall, or in response to significant warming.

Terrain and Travel

  • Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Be alert to conditions that change with elevation, aspect and exposure to wind.
  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.

Problems

Wind Slabs

An icon showing Wind Slabs

New snow is available to build wind slabs on mainly north through easterly aspects in response to strong southwesterly winds. Especially east of Terrace, a chance of step-down to lower layers exists, increasing the potential size for that part of the region.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1.5 - 3

Loose Wet

An icon showing Loose Wet

Loose wet avalanches up to size 1.5 were observed in steep terrain below 700 m on Thursday. Loose wet avalanche activity is expected to taper as freezing levels drop over the weekend.

Aspects: All aspects.

Elevations: Below Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 25th, 2020 5:00PM

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