North Columbia

Date Issued
    Monday, 15 February 2010 02:00 PM 
Valid Until
    Thursday, 18 February 2010 02:00 PM 
Next Update
    Tuesday, 16 February 2010 02:00 PM 

Cariboos

				Tuesday 		Wednesday 		Thursday
Alpine 			3 Considerable 	3 Considerable 	3 Considerable
At Treeline 	3 Considerable 	3 Considerable 	3 Considerable
Below Treeline 	2 Moderate 		2 Moderate 		2 Moderate

Monashees & Selkirks

				Tuesday 		Wednesday 		Thursday
Alpine 			3 Considerable 	3 Considerable 	3 Considerable
At Treeline 	3 Considerable 	3 Considerable 	3 Considerable
Below Treeline 	2 Moderate 		2 Moderate 		2 Moderate

Primary Concerns

Persistent Slab

Three layers of weak surface hoar are buried and are easily being triggered by skiers, snowboarders 
and snowmobilers in low angle terrain.

Special Message

An avalanche fatality has been reported in the Bewes Creek/Crazy Creek area of the Monashee Mountain 
Range just north of the Trans Canada Highway west of Revelstoke. At the moment there is only 
preliminary information regarding this incident. The avalanche involved two snowmobilers. One 
confirmed fatality. 

The avalanche occurred on a 40 degree slope at roughly 1900m on a north aspect. It was released on a 
weak layer of surface hoar buried 40-50cm. The fracture line was 30m wide and ran for 100m into a 
terrain trap.

Confidence: Fair

There is high variability in avalanche conditions within the region. However, I am confident that 
in the southwestern portions, it is likely that skiers, snowboarders and snowmobilers will trigger 
avalanches on open slopes in the alpine and at tree-line.

Weather Forecast

Tuesday another weak weather system is forecast with light accumulations of precipitation.

On Wednesday another stronger ridge of high pressure is forecast to build and encourage drier 
conditions through the rest of the week.

Avalanche Activity

Refer to the "Special Message" section for information on a recent avalanche fatality.

Rider triggered avalanches continue to be reported to size 2.5 on a variety of surface hoar layers 
in the top 50-60cm of the snowpack. Many of these avalanches are running in very low angle terrain. 
Numerous observers also report triggering these avalanches from quite a distance away from where 
the avalanches are actually running. This indicates that these layers are very sensitive to human 
triggerring. As snow continues to slowly accumulate and temperatures stay warm, the load on these 
layers will increase and the concern for triggering avalanches on these layers will remain.

Travel Advisory

Conditions are ripe for triggering avalanches.

Terrain to Watch: 

    * Avoid exposure to large slopes above you.
    * Wide open interconnected terrain over 25 degrees in steepness.
    * Steep slopes that roll-over into a steeper pitch such that the snowpack is unsupported 
	   from below.
    * Steep slopes above terrain traps like cliffs, jagged rocks, gullies, or depressions, where 
	   getting caught in a relatively small avalanche could have serious consequences.
    * Steep open areas in the trees above the 1500m elevation band.

Ways to Manage Risk:

    * Watch for obvious clues of unstable snow such as whumphing, hollow sounds, shooting cracks, 
	   or recent avalanches on similar slopes. If observed, back off to simpler terrain. 
    * Ride or cross slopes one at a time and spot from safe locations.
    * If companions get stuck on a slope, let them dig out on their own, reducing the amount of 
	   people exposed at any given time.

Snowpack

The February 8 surface hoar layer is buried by up to 30cm with test results in the very easy to 
easy and sudden range. This layer is one to watch because it was reported 10 to 30 mm in size. It 
was present on most slopes well up into the alpine. Another layer of surface hoar (January 25) is 
buried by up to 50cm. This layer is also reported to very reactive to stability tests and skier 
traffic. 

Prepared by Greg Johnson