Avalanche Forecast

Issued: Dec 7th, 2014 8:00AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs, Persistent Slabs and Loose Wet.

Peter, Avalanche Canada

Sea To Sky.

This Will be a Week of Dubyas: Windy, Wet and Warm! Expect increasing hazard and widespread natural avalanche activity by Tuesday.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Monday: Periods of rain or snow – 20-30mm or cm. The freezing level is around 1800 m and winds are 30-60 km/h from the S-SW. Tuesday: Rain, heavy at times. The freezing level could climb as high as 2500 m and winds could be gusting close to 100 km/h from the south. Wednesday: Continued heavy rain or snow. The freezing level remains above 2000 m and southerly winds should keep cranking.

Avalanche Summary

There have been no recent reports of avalanches in the past several days; however, I suspect it may be possible to trigger new wind slabs in open leeward terrain, particularly in the alpine.

Snowpack Summary

Recent snowfall amounts vary but in some areas above 1800 m there could be 20-40 cm of moist storm snow, which now covers the previous snow surface of surface hoar or facetted snow in sheltered areas, and pockets of old wind slab or a crust (from last weeks rain) in open wind-exposed terrain. Fresh new wind slabs are likely below ridges and terrain features on exposed north and east facing slopes. This new snow may also be covering old dense or hard wind slabs from the outflow winds we experienced during the recent dry spell. A solid rain crust is buried 20-50 cm deep up to around 2000 m. Another crust that was buried in mid-November is down 40-60 cm. The deeper crust may be associated with a layer of facets above or below. The snow pack depth drops significantly below treeline with essentially no snow below 1600 m.

Problems

Storm Slabs

Heavy snow or rain is forecast for the next few days. Deep and dense storm slabs could form at higher elevations and could release naturally or be triggered easily by the weight of a rider or snowmobile.

Be alert to conditions that change with elevation and avoid wind loaded slopes near ridge crests.>Expect conditions to deteriorate. Assess conditions continually as you travel and be prepared to change plans.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Heavy and rapid loading from snow, rain, and wind could be enough to wake up persistent weak layers and produce large avalanches.

Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Loose Wet

Expect heavy loose wet sluffs in steep open terrain and gullies, especially if snow accumulates and then it turns to rain.

Be aware of party members below you that may be exposed to your sluffs.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 8th, 2014 2:00PM