January 19, 2008
Whistler Avalanche conditions
January 19, 2008
Alpine: Moderate
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. 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. A dusting of new snow has freshened up the old surfaces.
Avalanche Activity: Explosive testing on Tuesday produced results that were for the most part 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. Similar occurrences have been observed on Blackcomb and in the backcountry. There was also 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 release in some isolated areas.
Snowpack: The snowpack over the alpine terrain is quite variable due to the strong winds accompanying the storm. You will find scouring, sastrugi, stiff windslabs, and some thin suncrust. All are now covered by a skiff of new snow. The storm snow layers are continuing to tighten, but some pockets of stiff windslab may still remain reactive to the weight of a person. The December 4th raincrust and facet crystal weakness is well buried in most areas, 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: Today’s flurries should taper by this afternoon and skies are expected to clear as a strong ridge of high pressure builds. Cool temperatures and clear skies are forecast to be with us into the middle part of next week.
January 19, 2008
Alpine: Moderate
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. 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. A dusting of new snow has freshened up the old surfaces.
Avalanche Activity: Explosive testing on Tuesday produced results that were for the most part 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. Similar occurrences have been observed on Blackcomb and in the backcountry. There was also 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 release in some isolated areas.
Snowpack: The snowpack over the alpine terrain is quite variable due to the strong winds accompanying the storm. You will find scouring, sastrugi, stiff windslabs, and some thin suncrust. All are now covered by a skiff of new snow. The storm snow layers are continuing to tighten, but some pockets of stiff windslab may still remain reactive to the weight of a person. The December 4th raincrust and facet crystal weakness is well buried in most areas, 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: Today’s flurries should taper by this afternoon and skies are expected to clear as a strong ridge of high pressure builds. Cool temperatures and clear skies are forecast to be with us into the middle part of next week.
