Avalanche Forecast
Issued: Jan 6th, 2012 9:58AM
The alpine rating is Wind Slabs, Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Forecast snowfall amounts are uncertain on Sunday
Weather Forecast
Flurries during the day on Friday should accumulate a couple of new cm by Saturday morning. A weak ridge of high pressure building over the coast is forecast to develop strong winds from the west or northwest and warm temperatures in the Cariboo. Moderate precipitation is expected to begin by midnight and continue during the day on Sunday. The freezing level is expected to rise to about 1800 metres in the Cariboo and West Monashee by Sunday morning. It looks like most of the snow will fall in the North and West of the Interior ranges. Expect moderate to strong northwest winds on Sunday becoming strong from the west in the South Columbia and Purcells. Cooler air is expected to move in to the region from the northwest on Monday. Precipitation amounts are un-certain at this time. Chinook conditions are expected for the Rockies.
Avalanche Summary
Some explosive and skier controlled avalanches up to size 1.5. Observations have been limited due to poor visibility and travel conditions.
Snowpack Summary
The storm slab is about 50 cm in this region. In the alpine and at treeline this new snow is being blown onto lee slopes and terrain features adding to previous soft slabs and wind slabs. In sheltered locations this new snow buries the surface hoar that formed over the New Years. We'll date this the January 3 SH layer, the crystals reported to be up to 10mm. This may become a concern with increased load as it reaches it's threshold. Some locations in the region received some rain up to 2000m, but consistent rain to 1500m. This may have solved our lower elevation New Years surface hoar layer. Below the surface down 80-140cms lurks the mid-December surface hoar/ crust/ facet layer. This is a layer of concern. Test results on this are still variable in the moderate to hard ranges with sudden planar characteristics. It continues to be sensitive to large triggers like cornice fall and explosives. Between this layer and the bottom of the snowpack sits a well settled mid pack. At the bottom of the snowpack basal facets and depth hoar crystals live. These become a concern in thinner snowpack areas, and became reactive under the new load of the post-Christmas storms.
Problems
Wind Slabs
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 7th, 2012 8:00AM