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Avalanche Forecast

Dec 6th, 2020–Dec 7th, 2020
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

A wet and warm storm will drop upwards of 25-50 cm through Monday. Along with strong, gusty winds and spiking freezing levels, expect rapid storm slab development and avalanche hazard increasing to HIGH near the end of the day.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

SUNDAY NIGHT: Flurries and snow, 5-10 cm by morning / Moderate, increasing to strong, south-southwest ridgetop wind / alpine low temperature -3 / Freezing level 1400 m

MONDAY: Snow, 20-50 cm / Strong, south-southwest ridgetop wind / alpine high temperature +1 / Freezing level rising to 2100 m

TUESDAY: Snow and flurries, 10-30 cm / Moderate, gusty southwest ridgetop wind / alpine high temperature -2 / Freezing level 2100 m and dropping

WEDNESDAY: Isolated flurries / Light, west ridgetop wind / alpine high temperature -3 / Freezing level 1000 m

Avalanche Summary

Outside of a few small loose-wet avalanches from steep terrain, there have been no avalanche observations since last Wednesday (Nov 2) when natural widespread wet loose avalanche cycle up to size 3 was triggered by warming.

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 covers most slopes resulting from recent sun and warm temperatures. Where cold, dry snow prevailed (upper elevations on more shaded and polar slopes), winds continue to press slabs into lee features. The snowpack depth varies with elevation. Below treeline 30 to 70 cm, 80 to 100 cm near treeline, and over 150 cm may be found in the alpine.

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 1500 m. This crust may have a thin overlying layer of weak faceted grains and/or surface hoar crystals, especially in sheltered areas around treeline. The incoming storm may provide insight on if these layers will be a concern going forward. 

Terrain and Travel

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

Avalanche Problems

Storm Slabs

A wet and warm storm will drop around 10 cm by Monday morning and upwards of 25-50 cm through the day. Along with strong, southwesterly winds and spiking freezing levels, expect rapid storm slab development and avalanche hazard increasing to HIGH near the end of the day.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1.5 - 2.5

Loose Wet

As freezing levels spike late Monday (and areas that get rain instead of snow), a wet loose hazard will persist anywhere the snowpack is moist or wet.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible

Expected Size: 1 - 2