Avalanche Forecast

Issued: Jan 31st, 2018 3:56PM

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

Avalanche Canada jlammers, Avalanche Canada

Significant accumulations of new snow are expected on Wednesday and Thursday. If winds are strong, the avalanche Danger may be HIGH.

Summary

Confidence

Moderate - Wind speed and direction is uncertain on Thursday

Weather Forecast

Wednesday Night: 15-30cm of new snow / Moderate southwest winds / Freezing level at 800mThursday: 5-10cm of new snow / Moderate southwest winds / Freezing level at 1000mFriday: 20-30cm of new snow / Light southwest winds / Freezing level at 1300mSaturday: Light flurries / Light and variable winds / Freezing level at 2000m

Avalanche Summary

Areas that experienced recent heavy rain should see the snowpack quickly stabilize as temperatures cool. With that said, new snow that accumulates on this refrozen surface may 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.Looking forward, new snow and wind on Wednesday night is expected to promote a new round of storm slab activity in higher elevation lee terrain.

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

An icon showing Storm Slabs
New snow and wind on Wednesday night are expected to form new storm slabs at all elevation bands. The new snow may be surprisingly reactive at lower elevations due to underlying crusts.
The new snow will need time to settle and stabilize.Be alert to conditions that change with elevation.Avoid all avalanche terrain during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2

Cornices

An icon showing Cornices
Recent heavy snowfall and high winds have created fragile new cornice growth. These monsters may surprise with nasty consequences. Use extra caution around ridge crests.
Give cornices a wide berth when travelling on or below ridges.Falling cornices may trigger avalanches on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Feb 1st, 2018 2:00PM