Danger ratings reflect higher forecast snowfall amounts for Thursday night. Danger could be slightly lower if less snow accumulates. Be sure to make keen local observations.
Summary
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Synopsis: A strong frontal system will reach the South Coast late on Friday and spread heavy to very heavy precipitation, strong winds, and briefly rising freezing levels into Saturday.Friday: Heavy snow developing late in the day 15-20 cm. Very strong SW winds. The freezing level should be around 1000 m during the day, but could peak at close to 1800 m during the storm. Saturday: Continued very heavy snow in the morning, easing through the day 20-30 cm. Winds are very strong from the SW but should ease to moderate from the W-NW later in the day. The freezing level rebounds to around 1000 m. Sunday: Moderate snowfall as another weaker frontal system slides in. The freezing level should be around 500-800 m.
Avalanche Summary
A size 2 deep persistent slab avalanche was reported on Blackcomb on Wednesday. This slide was accidentally triggered by a snow cat and failed on a weak facetted layer near the ground. Check out
Waynn Flann's avalanche blog for photos and more information. This avalanche highlights the potential for large and deep avalanches in many areas on the South Coast. Heavy loading Friday night and Saturday will most likely trigger full depth avalanches in some places.
Snowpack Summary
Around 10-25 cm of new snow overlies wind-pressed snow at upper elevations, surface hoar in sheltered terrain and a melt-freeze crust on previously sun-exposed slopes. Moderate to strong SW winds have probably formed new dense wind slabs in exposed lee terrain and cross-loaded features. The cold temperatures from early December have left weak faceted crystals that seem to be variably reactive. In higher elevation terrain where the snowpack was deeper, the facets likely co-exist with a crust in the mid pack. In lower elevation terrain or in shallow, rocky areas of the alpine, the facets are most likely more widespread and may exist down near the ground. Either way, the "wait 48 hours and you're good" Coastal mantra does not apply as these conditions are likely to persist for some time, and will probably become reactive with forecast snowfall.Early season riding hazards such as rocks, stumps and logs are lurking below the surface in many areas. In glaciated terrain open and poorly bridged crevasses are everywhere.
Peter,
Avalanche Canada
