Snowpack tightening up
Whistler Avalanche conditions
Friday, January 16, 2009 7:07 AM
For: Fri Sat Sun
Alpine Considerable Considerable Considerable
Treeline Considerable Considerable Considerable
Below Treeline Moderate Moderate Moderate
Travel Advisory:
A rapid change to warm temperatures in the alpine will add significant stress to the snowpack. While the surface layers have been gaining strength, the underlying facet weaknesses remains relatively unchanged. Numerous large slab avalanches have been observed over the past few days. Expect continued natural avalanche activity with the real possibility of skier triggered activity as well. Many results are likely to be very large.
Avalanche Activity:
We have been seeing natural remotely triggered avalanches, even in low angle terrain. Explosive testing and ski cutting carried out during the past week has produced numerous slab avalanches up to two meters in depth. They have been failing in the storm snow and in the facets above the December 6th crust. Some slopes at treeline elevations have run on a layer of depth hoar in the rocks and on the heather. Many settlement whumphs have also been felt. At lower elevations, rainfall produced widespread loose sluffing and snowballing. The unseasonally high freezing levels and solar radiation have produced wet loose slides up to size 2 on solar aspects, cornice failures have triggered slab avalanches up to size 2 as well.
Snowpack:
The current snowpack is very atypical for the West Coast. The shallow early December snowpack was exposed to prolonged cold temperatures which caused it to become weak and faceted. Depth hoar formed in shallow rocky terrain. Compounding this problem is the underlying Dec.6 raincrust that provides a nice hard sliding surface. The buried facets and depth hoar above and below the December 6 crust are likely the weak layers causing the settlement whumphs. The crust/facet combo is now buried up to 200 cm below the surface on some lee slopes. Not all start zones are running on the crust, but you can expect more widespread activity as the load above it grows. Rocky terrain is very rotten and will be particularly prone to deeper releases in the future. Below treeline terrain has a weak layer on the ground. We were seeing some avalanche activity at lower elevations, but the snowpack has since received a good rainfall and should have run in most areas.
Weather:
Mostly clear skies and very warm alpine temperatures are forecast to last through the weekend.
Friday, January 16, 2009 7:07 AM
For: Fri Sat Sun
Alpine Considerable Considerable Considerable
Treeline Considerable Considerable Considerable
Below Treeline Moderate Moderate Moderate
Travel Advisory:
A rapid change to warm temperatures in the alpine will add significant stress to the snowpack. While the surface layers have been gaining strength, the underlying facet weaknesses remains relatively unchanged. Numerous large slab avalanches have been observed over the past few days. Expect continued natural avalanche activity with the real possibility of skier triggered activity as well. Many results are likely to be very large.
Avalanche Activity:
We have been seeing natural remotely triggered avalanches, even in low angle terrain. Explosive testing and ski cutting carried out during the past week has produced numerous slab avalanches up to two meters in depth. They have been failing in the storm snow and in the facets above the December 6th crust. Some slopes at treeline elevations have run on a layer of depth hoar in the rocks and on the heather. Many settlement whumphs have also been felt. At lower elevations, rainfall produced widespread loose sluffing and snowballing. The unseasonally high freezing levels and solar radiation have produced wet loose slides up to size 2 on solar aspects, cornice failures have triggered slab avalanches up to size 2 as well.
Snowpack:
The current snowpack is very atypical for the West Coast. The shallow early December snowpack was exposed to prolonged cold temperatures which caused it to become weak and faceted. Depth hoar formed in shallow rocky terrain. Compounding this problem is the underlying Dec.6 raincrust that provides a nice hard sliding surface. The buried facets and depth hoar above and below the December 6 crust are likely the weak layers causing the settlement whumphs. The crust/facet combo is now buried up to 200 cm below the surface on some lee slopes. Not all start zones are running on the crust, but you can expect more widespread activity as the load above it grows. Rocky terrain is very rotten and will be particularly prone to deeper releases in the future. Below treeline terrain has a weak layer on the ground. We were seeing some avalanche activity at lower elevations, but the snowpack has since received a good rainfall and should have run in most areas.
Weather:
Mostly clear skies and very warm alpine temperatures are forecast to last through the weekend.
