Kootenay Boundary Avalanche Forecast

Date/Time issued: Monday, March 23, 2009 at 4:00 PM
Valid until: Thursday, March 26, 2009 at 6:00 PM

Next Scheduled Update: Wednesday, March 25, 2009

  				Tuesday 			Wednesday 			Thursday
Alpine 			3 - CONSIDERABLE 	3 - CONSIDERABLE 	3 - CONSIDERABLE
Treeline 		2 - MODERATE 		3 - CONSIDERABLE 	3 - CONSIDERABLE
Below Treeline 	2 - MODERATE 		2 - MODERATE 		2 - MODERATE

Confidence: Fair-good.

Primary Concerns:

    * Cornice: Cornice collapse is a real concern in the afternoon with warm temperatures and 
	  sunshine.

    * Persistent Slab: There are a number of weak layers that lie beneath the surface which could 
	  be triggered in the right spot or with a heavy load.
	  
    * Deep Slab: The possibility for triggering deep slabs on old bed surfaces from early January 
	  is particularly great in this region.

Travel Advisory   Issued: Mon, Mar 23 Next Scheduled Update: Wed, Mar 25

The big avalanche cycle that affected other regions on Friday and Saturday didn't seem to affect 
this region to the same degree, probably due to lower amounts of storm snow. Having said that, I 
would still be nervous of windslabs, especially on N and NE aspects above 1800m where the snowpack 
remained dry. I'd also be very nervous of riding on the big paths that slid in early January. On 
these, there is the chance for triggering full-depth avalanches to the lower basal facets. The 
trigger points would most likely be shallow, rocky and/or steep unsupported areas and I admit that 
the chance of triggering is quite low. However, the consequence of releasing a slide like this is 
huge, and should determine what terrain you select at this time.  I've got a spring equation for 
you. Don't panic, it's really simple. Sunny slopes + afternoon = bad. It's not just loose snow you 
have to worry about-there is a concern that slabs on a variety of lower layers could pull out in 
response to solar warming at this time. Aside from staying off southern slopes in the afternoon, 
you should steer well clear of any slope that is threatened by a cornice. Minimise your exposure 
to slopes from above and group up well away from big runouts.

Avalanche Activity   Issued: Mon, Mar 23 Next Scheduled Update: Wed, Mar 25

A skier accidental occurred on a steep, northeast slope at 2150m yesterday. The size 2 avalanche 
was narrow but ran for 250m and the crown depth was 120cm. Pinwheeling and numerous loose snow 
avalanches have been noticed on solar slopes in the afternoons.

Snowpack   Issued: Mon, Mar 23 Next Scheduled Update: Wed, Mar 25

Moist snow exists to 1800m on N aspects and even higher on S aspects. Recent storm snow has set 
into a dense (1F) upper slab. Interfaces in the storm layers are gaining strength and now quite 
well bonded. Several lower weak layers still exist: Mar-13; Mar-01; Feb-22; Jan-27; Jan-10. These 
layers are facets, decomposing surface hoar, crusts or some combination of these. The lower 
40-60cm of the snowpack comprises weak facets under old bed surfaces from the early January 
avalanche cycle.

Weather   Issued: Mon, Mar 23 Next Scheduled Update: Wed, Mar 25

Tuesday: 5cm snow although a convective cell in the afternoon could lead to locally higher amounts. 
Winds light from SW. Freezing level rising to 1600m during the day.

Wednesday: Light flurries in the morning. Ridge building later in the day bringing clear weather. 
Cooler temps but sunshine will make it feel warmer.

Thursday: High pressure giving clear skies. The ridge is pushed aside late on Thursday by a frontal 
system, which looks as though it will bring light amounts of snow to this region on Friday.

Issued by: James Floyer