January 17, 2008
Whistler Avalanche conditions
January 17, 2008
Alpine: Moderate trending Considerable with exposure to the sun
Treeline: Low
Below Treeline: Low
Travel Advisory: Monday's storm cycle brought a total of 25cm of new snowfall accompanied by strong winds from the south east. Temperatures were mild but fell rapidly with its passage. There has been significant drifting at alpine and treeline elevations and the resulting slabs are quite stiff. You can expect that the alpine terrain has developed many new features. Be wary of any hard hollow feeling areas of windslab, and keep in mind that large unpredictable avalanches are still very much a possibility in some isolated areas.
Avalanche Activity: Explosive testing on Tuesday produced results predominantly up to size 1.5 within the storm snow layers. Cornices have grown and were failing easily. Deep slab releases are continuing to occur sporadically with both large and small explosive triggers. One anomalous result was a size 3.5 with a fracture line up to 3.5m in depth produced with a 25kg charge. It ran on the December 4th crust and facet layer. This occurrence corresponds with similar deep slab releases on Blackcomb on Monday, and periodically during the past week in various backcountry regions. There was evidence of a fairly widespread natural avalanche cycle having occurred during the storm. You can expect to see lots of new cornice buildup – a falling cornice chunk could trigger a deep slab releas on the underlying slope in some isolated areas.
Snowpack: The snowpack over the alpine terrain is quite variable due to the strong winds accompanying the storm. You can expect to encounter wind scoured areas, as well as areas of sustrugi and very stiff windslab. Temperatures fell dramatically after the passage of the storm which helped the storm snow layers to tighten in. Although we have not observed any natural avalanche activity since the temperatures fell with the storms passage, the stiff windslabs may still remain reactive to the weight of a person in some isolated areas. The December 4th raincrust and facet crystal weakness continues to get buried deeper, but the crust can still be found on the surface in some wind affected terrain. Although this buried weakness has gradually been gaining strength, it continues to pop up sporadically, with the resulting avalanches getting larger and larger as the overlying snowpack grows. Its unpredictable nature is problematic and backcountry travelers should be cautious. The deep slab releases generally appear to be failing initially in a shallow part of the slab and propagating into the fatter part of the slope. Rocky start zones seem to be a common quality in these larger events. This persistent weakness is expected to be with us for some time to come.
Weather: A series of weak systems to the North will brush by our region periodically over the next several days bringing a mix of sun, cloud, and a chance of scattered flurries. Temperatures will remain cool at lower elevations, with an inversion. A more organized system may arrive on Saturday.
January 17, 2008
Alpine: Moderate trending Considerable with exposure to the sun
Treeline: Low
Below Treeline: Low
Travel Advisory: Monday's storm cycle brought a total of 25cm of new snowfall accompanied by strong winds from the south east. Temperatures were mild but fell rapidly with its passage. There has been significant drifting at alpine and treeline elevations and the resulting slabs are quite stiff. You can expect that the alpine terrain has developed many new features. Be wary of any hard hollow feeling areas of windslab, and keep in mind that large unpredictable avalanches are still very much a possibility in some isolated areas.
Avalanche Activity: Explosive testing on Tuesday produced results predominantly up to size 1.5 within the storm snow layers. Cornices have grown and were failing easily. Deep slab releases are continuing to occur sporadically with both large and small explosive triggers. One anomalous result was a size 3.5 with a fracture line up to 3.5m in depth produced with a 25kg charge. It ran on the December 4th crust and facet layer. This occurrence corresponds with similar deep slab releases on Blackcomb on Monday, and periodically during the past week in various backcountry regions. There was evidence of a fairly widespread natural avalanche cycle having occurred during the storm. You can expect to see lots of new cornice buildup – a falling cornice chunk could trigger a deep slab releas on the underlying slope in some isolated areas.
Snowpack: The snowpack over the alpine terrain is quite variable due to the strong winds accompanying the storm. You can expect to encounter wind scoured areas, as well as areas of sustrugi and very stiff windslab. Temperatures fell dramatically after the passage of the storm which helped the storm snow layers to tighten in. Although we have not observed any natural avalanche activity since the temperatures fell with the storms passage, the stiff windslabs may still remain reactive to the weight of a person in some isolated areas. The December 4th raincrust and facet crystal weakness continues to get buried deeper, but the crust can still be found on the surface in some wind affected terrain. Although this buried weakness has gradually been gaining strength, it continues to pop up sporadically, with the resulting avalanches getting larger and larger as the overlying snowpack grows. Its unpredictable nature is problematic and backcountry travelers should be cautious. The deep slab releases generally appear to be failing initially in a shallow part of the slab and propagating into the fatter part of the slope. Rocky start zones seem to be a common quality in these larger events. This persistent weakness is expected to be with us for some time to come.
Weather: A series of weak systems to the North will brush by our region periodically over the next several days bringing a mix of sun, cloud, and a chance of scattered flurries. Temperatures will remain cool at lower elevations, with an inversion. A more organized system may arrive on Saturday.
