North Columbia Avalanche Forecast

Date/Time issued:
    Wednesday, January 14, 2009 at 5:00 PM
Valid until:
    Saturday, January 17, 2009 at 6:00 PM
Next Scheduled Update:
   Friday, January 16, 2009

---------- Cariboos ----------
  				Thursday 			Friday 				Saturday
Alpine 			4 - HIGH 			4 - HIGH 			4 - HIGH
Treeline 		4 - HIGH 			4 - HIGH 			4 - HIGH
Below Treeline 	3 - CONSIDERABLE 	3 - CONSIDERABLE 	3 - CONSIDERABLE

---------- Monashees & Selkirks ----------
  				Thursday 			Friday 				Saturday
Alpine 			4 - HIGH 			4 - HIGH 			4 - HIGH
Treeline 		4 - HIGH 			4 - HIGH 			4 - HIGH
Below Treeline 	3 - CONSIDERABLE 	3 - CONSIDERABLE 	3 - CONSIDERABLE

Confidence: Good for the weather forecast. Fair with respect to snowpack behaviour with expected 
warming.

Primary Concerns:

    * Persistent Slab: The potential for triggering avalanches in thin snowpack areas associated 
	  with a facet layer will increase with warming.
    * Wind Slab: Weak windslabs are lurking on the north through east side of ridge crests and 
	  terrain features on treeline and alpine slopes as well as open slopes below treeline.
    * Cornice: The chance of cornice failure increases with warming.

Travel Advisory   Issued: Wed, Jan 14 Next Scheduled Update: Fri, Jan 16

Significant warming is expected to continue for the forecast period. This has several effects on 
avalanche danger. First the good news: existing windslabs should be strengthening and the snow 
available for transport into new windslabs should diminish. Now for the bad news: cornices are 
expected to fail and wet loose-snow avalanches are likely, especially on steep sun-exposed slopes 
in the afternoon - both could potentially trigger large slab avalanches.  Finally, the likelihood 
of people triggering large slab avalanches will increase as slabs soften and there are more 
potential trigger points.  The clear and warm weather will undoubtedly make big open alpine 
terrain appealing. But remember that safe travel will depend on giving cornices a wide berth when 
travelling on or below ridges, avoiding convexities and thin snowpack areas, exercising caution 
around wind-exposed ridge crests and terrain features and minimizing travel on or below steep, 
large and open slopes, especially in the afternoon.

Avalanche Activity   Issued: Wed, Jan 14 Next Scheduled Update: Fri, Jan 16

Several very large size 2.5-3.5 natural and explosive-triggered avalanches ran on facets overlying 
a crust down approximately 200cm. Several more natural and explosive-triggered avalanches 
sufficiently large to bury, injure or kill a person ran primarily on north through east aspects 
on a layer of facets down 80-120cm. Recent storm snow is failing easily producing avalanches up 
to size 1.5 that are running far.

Snowpack   Issued: Wed, Jan 14 Next Scheduled Update: Fri, Jan 16

10 to 20cm of new snow and the recent storm snow is settling and adding to the slab overlying a 
weak facet layer buried over Christmas, which is now up to 110cm thick in some places. This PWL 
is fracturing with variable but often easy effort in snowpack tests and showing propensity to 
propagate fractures over large distances. Below the well settled mid-pack lies more facets and 
crusts buried late in November and early in December. Hard and soft windslabs are now lurking 
on just about any alpine an open treeline slope. Freezing rain at lower elevations have created 
a hard crust on the surface.

Weather   Issued: Wed, Jan 14 Next Scheduled Update: Fri, Jan 16

Thursday: Dry, a mix of sun and clouds, moderate to strong northwesterly mountaintop winds, 
valley cloud in the morning and a temperature inversion with alpine highs reaching 2 degrees.

Friday and Saturday: Dry, partly cloudy, moderate westerly mountaintop winds, valley cloud in 
the morning and a temperature inversion with alpine highs reaching 4 degrees.

Issued by: Cam Campbell