Avalanche Forecast

Issued: Jan 29th, 2018 5:12PM

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

cgarritty, Avalanche Canada

South Coast.

Another dose of new snow for all elevations as the storm tapers and temperatures cool. Watch for new snow that feels stiff or slabby from wind effect and increase caution in the alpine where the storm delivered heaps of new snow instead of rain.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Monday night: Continuing flurries bringing approximately 5 cm of new snow as freezing levels drop to 800 metres. Strong southwest winds.Tuesday: Cloudy with continuing flurries bringing approximately 10 cm of new snow. Moderate southwest winds. Freezing level to 700 metres with alpine high temperatures of -3.Wednesday: Cloudy with flurries bringing 10-15 cm of new snow. Light west winds. Freezing level to 600 metres with alpine temperatures of -4.Thursday: Cloudy with flurries bringing approximately 15 cm of new snow. Light south winds. Freezing level to 600 metres with alpine temperatures of -4.

Avalanche Summary

Reports from Saturday included one MIN submission detailing a near miss incident involving several members of a ski touring party on Hollyburn Mountain. Two skiers were partially buried and one was fully buried in a large storm slab that released from a steeper pitch below treeline. Please see the MIN submission for details. Other MIN reports from the region over the past two days have shown ski cutting easily producing storm slab results at the depth of each day's accumulations.Looking forward, areas that experienced heavy rain should see the snowpack quickly stabilize as temperatures cool. With that said, new snow that accumulates on this refreezing surface will likely form unstable new storm slabs before the new snow has a chance to form a solid bond. High alpine areas that haven't seen rain are on a different trajectory. Here, recently formed storm slabs will need more time to stabilize as they experience continued loading from new snow and wind.

Snowpack Summary

Heavy rainfall soaked the upper snowpack at most elevations over Sunday night and Monday. High alpine elevations in areas like Sky Pilot and the Chehalis Range may have seen thick new storm slabs develop over the same time period. Below these elevation-dependant surface conditions, storm snow totals from the past week reached 110-180 cm. The crust that exists beneath these recent snow accumulations is likely to have now formed a solid bond to the overlying snow.

Problems

Storm Slabs

Snowfall will continue as freezing levels drop on Tuesday. With southwest winds remaining moderate to strong, touchy new slabs are likely to form on the snow surface. Thicker, more reactive slabs can be expected in the alpine and in lee areas.

Be alert to conditions that change with elevation.The new snow will need time to settle and stabilize.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Large amounts of recent new snow and high winds have been creating rapid cornice growth.

Falling cornices may trigger avalanches on slopes below.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Valid until: Jan 30th, 2018 2:00PM