Avalanche Forecast

Issued: Jan 29th, 2021 4:00PM

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

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Stay warm and watch for lingering wind slabs in steep open terrain.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Cold weather persists as a Pacific frontal system to the south brushes the region with a bit of cloud and isolated flurries.

FRIDAY NIGHT: Cloudy with some isolated flurries and accumulations of 2-5 cm, 20 km/h northeast wind, temperatures around -20 C.

SATURDAY: Cloudy with some isolated flurries in the morning then clearing in the afternoon 30 km/h northeast wind, temperatures between -20 and -25 C.

SUNDAY: Mix of sun and cloud, light wind, temperatures between -20 and -25 C.

MONDAY: Mostly cloudy with some isolated flurries, light wind, temperatures between -20 and -25 C.

Avalanche Summary

Several naturally-triggered wind slab avalanches were observed around White Pass earlier this week. They were on all aspects, roughly 40-50 cm thick, and ranged in size between 1-2.5. No significant changes since then suggest these wind slabs still exist, but are now more difficult to trigger.

Snowpack Summary

Frigid temperatures are softening the surface snow, which consists of old wind slabs in open terrain and some soft pockets in sheltered terrain. Wind affect is widespread above 1200 m.

A buried weak layer of surface hoar may still be found around 90 cm deep. It was found around Log Cabin and also in Powder Valley (see here). Avalanche activity on this layer hasn't been reported since the first week of January and isn't expected to spike without a substantial snowfall or warming trend.

The lower snowpack is strong around White Pass but a thinner and weaker snowpack structure is expected inland, such as in the Wheaton Valley and the south Klondike.

Terrain and Travel

  • Watch for areas of hard wind slab on alpine features.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

Problems

Wind Slabs

An icon showing Wind Slabs

Shifting wind earlier in the week has left widespread wind slabs in the alpine and open treeline terrain. These slabs are becoming less likely to trigger, but you should still travel with caution around steep terrain with slabby surfaces.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 30th, 2021 4:00PM