Avalanche Forecast
Issued: Nov 29th, 2012 9:21AM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Poor - Due to limited field observations for the entire period
Weather Forecast
Cool arctic air remains embedded in Northern Regions bringing light snow amounts and moderate SE winds. Strong outflow winds will persist through Friday, easing off Saturday. The arctic air will keep cold surface temperatures through the weekend with no inversions. Friday: FLVLâs surface, snow amounts near 5 cm, ridgetop winds SE 30 km/hr with strong valley outflows, alpine temps -12.Saturday: FLVLâs surface, snow 5-8 cm, ridgetop winds SE 20km/hr, alpine temps -9.Sunday: FLVLâs surface, snow amounts 5-10 cm, ridgetop winds SE 25 km/hr, alpine temps -11.
Avalanche Summary
No recent avalanche activity has been reported.The most recent reports came in on Wednesday with a notable event that occurred earlier in the week, during a period of colder temps where natural icefall induced avalanches occurred size 2.5-3.0. On Tuesday a flight through the Bear Pass area saw numerous old (previous 3 days) large natural avalanches. These were size 2-3, 50-80 cm deep, in the immediate lee around 1600-2000 m. Last Monday around the Shames area a size 3.0 avalanche was observed on a north-northeast aspect at 1500m, which may have been a thick wind slab or possibly released on a facets near the ground.Natural avalanche activity will likely pickup again with more snow and wind in the forecast. Rider triggered avalanches are likely, particularly in exposed wind loaded terrain.
Snowpack Summary
New storm slabs and wind slabs instabilities will be developing through the forecast period and continue to load a couple of weaknesses that exist lower in the snowpack. The first weak layer (from the top down) lies an old storm snow weakness from the past week. This has been found down around 60-80 cm. I suspect the cooling trend that existed in the earlier part of the week may have helped stabilize that interface. If it's still reactive, the current new snow load may act as a trigger, and larger avalanches could occur. The second weakness sits near the base of the snowpack. A recent profile at 1200m in the Shames area showed a thin layer of facets sitting on a crust 35cm off the ground. An Extended Column Test produced easy results on this layer, but the resistant fracture did not propagate across the entire column. Total snowpack depth is probably around 150cm in most treeline areas and deeper but more variable in the alpine. The snowpack below treeline may still be below threshold depth for avalanches in some areas. Check out the Skeena/ Babine discussion forum for more information from the area.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 30th, 2012 2:00PM