Canadian Avalanche Centre PAF Issued: January 6, 2006 at 1700 Valid Until: January 9, 2006 North Columbia Region Avalanche Forecast Forecast Area: This forecast includes the north part of the Monashee, Cariboo and Selkirk Ranges of the Columbia Mountains. This region includes areas north & east of Kamloops east of the Fraser Plateau north to Prince George, the Cariboos & Selkirks west of the Rocky Mountain trench between McBride & Golden and areas north of Hwy 1 between Kamloops & Golden.This forecast region does not include Glacier National Park. Forecast of avalanche danger beginning Friday, January 6, 2006: Day:\Friday p.m.\Saturday\Sunday\Monday Alpine:\Considerable\Considerable\Considerable\Considerable Treeline:\Considerable\Considerable\Moderate\Considerable Below Treeline:\Moderate\Moderate\Moderate\Moderate Travel Advisory: The storms dousing the Coast are just bringing dribs and drabs of snow to the northern Selkirks, Monashees and Cariboos, but it is starting to stack up and good to excellent riding conditions are being reported. Most professionals and experienced people I~Rve spoken with about the snowpack in recent weeks say that they do not trust it very much. I don~Rt either. This is because it is difficult to tell what will happen if you weight a number of a number of buried weak layers and storm snow weaknesses. The way people are safely riding in the mountains is carefully selecting terrain. This is not any easy task and takes some thought and skill to figure it out. Even then sometimes you are wrong. Take the time to figure out what types of terrain lay ahead of you and think about where you may trigger a slide and the consequences of getting caught up in one. Avalanches: Surprisingly there is not more avalanche activity being reported. In my mind it is kind of eerie, but perhaps it is because for the most part people are being cautious. On Thursday some descent sized natural avalanches were reported from steep terrain and a few small avalanches were triggered by skiers on a number of aspects. Snowpack: This is the tricky part, describing the snow structure in short order. A number of storm snow shears exist in the top layers of the snowpack on Friday. Old storm snow layers will strengthen and new ones will form through the weekend. Buried anywhere between 30 and 120 cm is the Christmas crust which extends to 2000 to 2400m. Most areas report a good bond, but some observers report faceting over the last week. Buried deeper are the Dec 19 facets and the November 25 crust. These layers have many people acting cautious in the mountains. Weather: On Friday night expect 5 cm of snow and 5 to 10 cm on Saturday. On Sunday evening a strong storm should spread a significant amount of snow through Monday evening. Storm amounts may be in the 20 30 cm range. The freezing level through the weekend will probably decrease to valley bottom by Sunday. This should put temperatures at treeline near -7. The wind will blow at times in the alpine predominately from the southwest. On Friday night expect 60 t 70 km/hr winds, easing on Saturday, but picking up again on Sunday. South Columbia Region Avalanche Forecast Forecast Area: This forecast includes the southern Columbia Mountains, including the Monashee, Selkirk and Purcell Mountain ranges. This region includes the eastern side of the Okanagan Valley from Osoyoos to Enderby, areas south of Highway 1 from Sicamous to Golden, areas west of the Columbia River between Golden & Kimberley, and areas north of Kaslo and Castlegar. This forecast region does not include Glacier National Park. Forecast of avalanche danger beginning Friday, January 6, 2006: Day:\Friday p.m.\Saturday\Sunday\Monday Alpine:\Considerable\Considerable\Considerable\Considerable Treeline:\Considerable\Considerable\Considerable\Considerable Below Treeline:\Moderate\Moderate\Moderate\Moderate Travel Advisory: The main areas of concern remain wind exposed areas at treeline and above where recent winds have formed slabs. Since the winds have been predominantly from the south and west, expect to find slabs on north and east facing terrain near ridges opposite to the primary wind direction. Steep, convex (rounded) terrain will also be common areas to find potentially unstable windslabs. The second (possibly more important) concern is the weak layer of faceted snow buried below the crust below 2000-2400 m and under the storm snow above that. Whumpfing (settlements) and ~Sdrops~T in stability tests both indicate that this deeply buried layer has not healed and could potentially be triggered if an avalanche were to step down to it. Avalanches: Most reported avalanches were small (Size 1) and occurred in the top 20-50 cm of the snowpack either within the storm snow or on the Dec. 25th crust. Expect most natural avalanche activity to subside by Saturday, but it will remain easy to trigger slab avalanches this weekend, especially near ridges. Snowpack: Snowpack structure and stability varies across the forecast region from the typical pattern of east to west. New snow amounts varied considerably from about 10 cm around Panorama up to 40 cm in the Nakusp area. What is consistent is that most observers report that wind formed soft slabs in wind- exposed areas at and above treeline. Some areas report easy to moderate stability test results and that these layers are reactive to ski cutting. The recent storm snow lies on top of the Christmas crust buried 50-70 cm deep, extending up to about 2000 to 2400 m. Below this crust is the layer to be very concerned about: the December 20th facet/surface hoar combination buried up to 100 cm deep. This layer is producing moderate ~Sdrops~T in stability tests, which is indicative of a still very weak, deeply buried layer. Weather: After a break Friday afternoon, the storm track will continue to bring snow through the weekend. Expect 5-10 cm of snow Friday night, another 5-10 cm of snow during a series of flurries Saturday and overnight into Sunday, mostly dry conditions Sunday, followed by snowfall of uncertain amounts Monday. The freezing level will drop from about 1600 m Friday to 1200 m Saturday, and likely to the valley bottom Sunday and Monday. Wind will be gusty from the southwest with the passage of fronts through the weekend. Issued by: aj Canadian Avalanche Center