Avalanche Forecast Sea to Sky

Date Issued: Valid Until:

Avalanche Canada jfloyer, Avalanche Canada

Avalanche Forecast

Fri Jan. 20th ยท 9:30AM

Alpine

Danger Ratings High

Treeline

Danger Ratings High

Below Treeline

Danger Ratings High
Storm Slabs Storm Slabs
Wind Slabs Wind Slabs

Alpine

Danger Ratings High

Treeline

Danger Ratings Considerable

Below Treeline

Danger Ratings Considerable

Alpine

Danger Ratings High

Treeline

Danger Ratings High

Below Treeline

Danger Ratings Considerable
Very heavy, coastal-style snowfall amounts are falling on a cold, interior-style snowpack. Unusual and dangerous avalanche conditions are anticipated.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Friday night: Up to 30-40 cm new snow expected. Strong to extreme ridgetop winds will blow from the SW.Saturday: Further heavy snowfall is expected, associated with the passage of a cold front. Amounts of 20-30 cm expected. Winds veering to strong westerly. Freezing levels spiking briefly to around 1500 m.Sunday: Another winter storm arrives bringing around 15-20 cm additional snow late in the day and strong winds. Temperatures should be slightly cooler, with freezing levels around 1000 m.Monday: Continued heavy precipitation is likely in localized areas with unstable convective air that moves in following Sunday's storm system. Strong SW winds. Freezing levels remaining around 1000m.

Avalanche Summary

Only sluffing in steep terrain was observed on Thursday and Friday. However, I anticipate avalanche activity will rapidly increase in response to heavy forecast snow amounts and warming temperatures.

Snowpack Summary

Dense new snow is forming a fresh storm slab on the snow surface. The underlying snow was cold and low density--it will likely act as a weak layer, enhancing the likelihood of slab avalanches during and after the current winter storm. A rain crust lies buried approximately 40 cm below the snow surface at lower elevations (up to around 1800 m). Reports indicate the bond at this interface is quite good, although the slick nature of the crust may still provide a sliding layer in some steeper locations. Concern for lower snowpack layers has diminished and remains only in shallow snowpack areas. Facets associated with a crust from mid-December and/or sugary facets at the base of the snowpack may still be a concern in shallow areas. Fragile cornices are still looming.

Problems

Storm Slabs

Storm Slabs

Very heavy amounts of dense new snow will fall on existing cold, low density surfaces. This will create a highly unstable upper snowpack with the potential for unusual avalanche activity.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 6
Wind Slabs

Wind Slabs

New snow and strong winds will set up touchy new wind slabs.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 4