Avalanche Forecast

Issued: Feb 2nd, 2018 5:52PM

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 mgrist, Avalanche Canada

Snow totals are very uncertain in this weather pattern. Danger ratings are based on the higher forecast amounts of snow. New snow may add to wind slabs caused by extreme winds from Friday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

Saturday: Snow (5 - 20cm possible) / Light to moderate westerly winds / Freezing level 1800m dropping to 1000m in the afternoon. Sunday: 5-25cm of new snow / Moderate southwest winds / Freezing level at 1500mMonday: Isolated flurries / Light north westerly winds / Freezing level at 1400mNote: Confidence is low for forecast wind values and precipitation amounts on Saturday and Sunday.

Avalanche Summary

On Friday ski cutting produced several size 1 soft slabs on immediate down wind (lee) features. Explosives control on Thursday and Friday triggered cornices at ridge crests, mostly Size 1.5 - 2. Looking forward, light amounts snow and strong winds on Friday are expected to promote a new round of wind slab activity in higher elevation lee terrain.

Snowpack Summary

On Friday morning only 3-5cm of new snow had fallen overnight as temperatures warmed up to +1 at tree line. Winds, however, were strong to extreme from the south (gusting to 121 Km/hr at the peak of Whistler) and created fresh wind slabs in exposed downwind (lee) terrain. At lower treeline and below, generally light amounts of snow now overlie a melt-freeze crust which formed during last Monday's warm storm. The new snow adds to the 170cm of snow that fell during the last few weeks of January. These series of storms were accompanied by strong to extreme winds which resulted in extensive scouring and impressive cornice growth in upper elevation terrain. These accumulations sit on a crust from mid-January which generally shows signs of bonding to the overlying snow; however, it has the potential to "wake-up" with a large trigger such as a cornice fall.Below this, the snowpack is thought to be generally strong and well-settled.

Problems

Storm Slabs

An icon showing Storm Slabs
Areas with high amounts of new snow could be primed for storm slabs whereas areas that see less snow may be more susceptible to wind slabs.
Be cautious as you transition into wind affected terrain.Be alert to conditions that change with elevation.Stay off recent wind loaded areas until the slope has had a chance to stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Cornices

An icon showing Cornices
Recent heavy snowfall and high winds have formed fragile new cornices. 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 large avalanches on the slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Feb 3rd, 2018 2:00PM