Avalanche Forecast

Issued: Nov 26th, 2014 8:00AM

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

Peter, Avalanche Canada

Sea To Sky.

Stormy, wet, and mild weather (a pineapple express) will maintain high avalanche danger on Thursday. It's best to wait out the storm or stick to simple, low-angle slopes.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Summary: Mild and wet on Wednesday and Thursday following by cool and dry for Friday and into the weekend. Thursday: 15-25 mm Weds night and 30-45 mm on Thursday. The freezing level is near 2000 m. Ridge winds are moderate to strong from the southwest. Friday: Possible lingering flurries. The freezing level drops to around 500 m. Winds ease to light or moderate. Saturday: Mainly sunny. The freezing level is at valley bottom and ridge winds are moderate from the N-NE.

Avalanche Summary

Numerous size 1-1.5 natural and skier-triggered storm slab avalanches were reported from the Whistler area over the past couple of days, mostly in the upper treeline and lower alpine elevation band. One was an accidentally triggered slab that pulled a skier off a small cliff. Fortunately there were no injuries.

Snowpack Summary

It's likely that snow continues to fall at higher elevations (above 2000 m). Below this elevation recent snowfall has probably been soaked by rain, or will be. As temperatures drop later this week I would expect a new crust to form, possibly with some fresh snow on top. An old snow surface of weak facets sitting on a crust is now down as much as 50-60 cm at treeline elevations and deeper in the alpine. Initial reports suggest this weakness is most pronounced slopes at upper treeline and lower alpine elevations. However, as we begin our forecasting season, we are working with limited information from the field. Check the bond of the snowpack at this level and take a cautious approach as new snow builds deeper above this layer.

Problems

Storm Slabs

Heavy snow and/or rain could overload buried weaknesses in the mid or lower snowpack. Also, if temperatures cool and snow starts to pile up we could see a new storm slab develop.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

Forecast rain could trigger loose wet sluffs in steep open terrain, primarily at and below treeline.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid travelling on ledges and cliffs where sluffing may have severe consequences.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Nov 27th, 2014 2:00PM