South Columbia Avalanche Forecast

Date/Time issued:
    Friday, January 09, 2009 at 5:00 PM
Valid until:
    Monday, January 12, 2009 at 6:00 PM
Next Scheduled Update:
   Monday, January 12, 2009

\---------- S. Selkirks & S. Monashees ----------
  				Saturday 	Sunday 				Monday
Alpine 			4 - HIGH 	4 - HIGH 			4 - HIGH
Treeline 		4 - HIGH 	4 - HIGH 			4 - HIGH
Below Treeline 	4 - HIGH 	3 - CONSIDERABLE 	4 - HIGH

---------- Purcells ----------
  				Saturday 	Sunday 				Monday
Alpine 			4 - HIGH 	4 - HIGH 			4 - HIGH
Treeline 		4 - HIGH 	4 - HIGH 			4 - HIGH
Below Treeline 	4 - HIGH 	3 - CONSIDERABLE 	4 - HIGH

Confidence: Good for tomorrow. Poor for Sunday and Monday due to difficult meteorological 
forecasting conditions and uncertainty with how the snowpack will respond to additional loading.

Primary Concerns:

    * Storm Snow: Heavy recent snowfall (with more forecast) has created storm instabilities on 
	  all aspects and elevations.
    * Deep Slab: The persistent facets in the lower snowpack won't go away. This widespread weak 
	  layer is very dangerous and is producing large, deep, destructive avalanches.

Special Message:   A series of storms has overloaded the snowpack in this region. We are in a 
period of widespread avalanche activity, with no confidence that we have seen the end of it. 
Breaks between storms are short, or non-existent. Even when storms subside, big destructive 
avalanches will remain possible. This situation will likely persist for some time into the 
future.

Travel Advisory   Issued: Fri, Jan 9 Next Scheduled Update: Mon, Jan 12

We're dealing with a fundamentally unstable snowpack that has proven itself capable of 
producing big, full depth avalanches that have run full path and into unusual areas. Previously 
skied slopes and stands of mature timber have been taken out during this cycle. Experienced 
practitioners with 30 years of experience are saying this is an extraordinary snowpack not to 
be messed with. There is no confidence that things will improve over the weekend and into Monday. 
A great many paths have not released but are poised to go. There is more snow and wind on the 
way. There are fluctuating temperatures. Any respite will be short-lived and thwart with 
uncertainty. If you're a skier, my best advice is to go cross country skiing, use your touring 
setup in low angled areas away from all avalanche terrain, or go skiing at the hill. If you're 
a sledder, stay on valley bottom roads in dense timber well away from any open slopes above. Keep 
in mind the unusual nature of the snowpack means avalanches could run beyond normal runout zones 
and into dense mature forest. Sobering? For sure.

Avalanche Activity   Issued: Fri, Jan 9 Next Scheduled Update: Mon, Jan 12

On Wednesday and Thursday this week there was a widespread natural avalanche cycle. Avalanches 
were reported to size 4, which is big enough to destroy several buildings or a large stand of 
timber. That is exactly what happened with one reported slide, which took out 2-3 hectares of 
mature forest, running into an area where no one has seen a slide run in living memory. Avalanches 
have been running on all aspects and at all elevations. While these avalanches have tapered off 
today, there is no reason to believe that further loading by new snow, wind or human activities 
such as a skiing or a snowmobiling will not trigger more of these monsters.

Snowpack   Issued: Fri, Jan 9 Next Scheduled Update: Mon, Jan 12

In the S. Selkirks and S. Monashees, 100-140cm of storm snow sits above a weak lower snowpack 
comprised of facets and facet/crust combinations. In the Purcells, 70-110cm of storm snow lies 
above an even more sugary lower snowpack. The storm snow has settled into a cohesive slab. Clean 
shears (both "pops" and "drops") have been reported on the facet/storm snow interface, indicating 
the potential for wide propagation. Whumpfs and shooting cracks have been reported from many 
areas in the region. Moist snow fell to around 1500m, which has likely set into a thin, unsupportive 
melt freeze crust. This now lies buried under approximately 20cm of fresh new snow.

Weather   Issued: Fri, Jan 9 Next Scheduled Update: Mon, Jan 12

Saturday: 15-20cm of new snow with strong westerly winds blowing to 80km/h at treeline. Freezing 
level should remain at valley bottom, although a brief rise in freezing level to around 1000m is 
possible on Saturday evening.

Sunday: Light snowfall with temperatures rising to 1500m. Some clear periods. Continued strong 
westerly winds.

Monday: Light to moderate snowfall with freezing levels rising to 1500-2000m. Winds moderate to 
strong from the southwest.

Issued by: James Floyer