Tuesday, January 20, 2009
Whistler Avalanche conditions
:�Tuesday, January 20, 2009 7:51 AM
For: Tue Wed Thu
Alpine Considerable Considerable Considerable
Treeline Considerable Considerable Considerable
Below Treeline Moderate Moderate Moderate
Note: If you do manage to trigger down to the facet/crust layer a stiff slab now sits on top of it creating an avalanche the would most likely be unsurvivable due to large frozen chunks of snow that would grid you into pulp.
Travel Advisory:
The amazingly warm temperatures are finally starting to affect the surface layers on solar aspects. The upper snowpack is warming and trending towards strengthening, but the underlying facet weakness remains relatively unchanged. Numerous large slab avalanches have been observed over the past week. Expect continued natural avalanche activity with the real possibility of skier triggered activity as well. Many results are likely to be very large. The avalanche danger will increase through the day.
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 and 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 is quite variable depending on aspect and elevation. Some areas have been crusted over while others have a layer of surface hoar sitting on winterlike snow.
Weather:
Mostly clear skies and very warm alpine temperatures are forecast to last into mid week. As the ridge begins to break down we should see increasing cloud cover on Thurs and Fri with freezing levels gradually falling to around 1000m, and snow flurries possible on Saturday. Enjoy the sunshine while it lasts, as payback time will arive at some point this winter!!
Backcountry travel is not advised at this time due to the weak and unpredictable nature of the snowpack
:�Tuesday, January 20, 2009 7:51 AM
For: Tue Wed Thu
Alpine Considerable Considerable Considerable
Treeline Considerable Considerable Considerable
Below Treeline Moderate Moderate Moderate
Note: If you do manage to trigger down to the facet/crust layer a stiff slab now sits on top of it creating an avalanche the would most likely be unsurvivable due to large frozen chunks of snow that would grid you into pulp.
Travel Advisory:
The amazingly warm temperatures are finally starting to affect the surface layers on solar aspects. The upper snowpack is warming and trending towards strengthening, but the underlying facet weakness remains relatively unchanged. Numerous large slab avalanches have been observed over the past week. Expect continued natural avalanche activity with the real possibility of skier triggered activity as well. Many results are likely to be very large. The avalanche danger will increase through the day.
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 and 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 is quite variable depending on aspect and elevation. Some areas have been crusted over while others have a layer of surface hoar sitting on winterlike snow.
Weather:
Mostly clear skies and very warm alpine temperatures are forecast to last into mid week. As the ridge begins to break down we should see increasing cloud cover on Thurs and Fri with freezing levels gradually falling to around 1000m, and snow flurries possible on Saturday. Enjoy the sunshine while it lasts, as payback time will arive at some point this winter!!
Backcountry travel is not advised at this time due to the weak and unpredictable nature of the snowpack
