March 17, 2003 SOUTH COAST REGION WEATHER: With the memory of last week^Òs epic storm still fresh in our minds, alpine temperatures have cooled as of Sunday. A showery unstable air mass is over us, producing significant new snow. Accumulations over the weekend were enough to reload avalanche start zones. A weakening trowel will arrive Tuesday night with more light to moderate snow. A brief trend toward clearing may appear Wednesday. SNOWPACK: A thick slab has formed at the surface and the new snow has added even more load onto deeper instabilities. On the outer coast the snowpack surface is rain soaked at all elevations. Cornices have grown quickly and will remain fragile. Sunny aspects will moisten and weaken during the afternoons. The snowpack is weak and isothermal to 1600m and is melting below 1000m. A surface crust formed overnight Sunday. AVALANCHES: Explosive control was still producing slabs to size 2.5 in previously unreleased rocky terrain on Sunday and Monday. Numerous smaller skier and explosive controlled slabs were triggered within the storm snow. On the drier eastern side of the Coast Mountains, over 90% of the avalanche paths ran during the big storm last Thursday, producing predominantly larger releases to size 4.5. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 19th) ALPINE ^Ö Considerable TREELINE ^Ö Considerable BELOW TREELINE ^Ö Moderate TRAVEL ADVISORY: The mountains are slowly dissipating tension in the snowpack from all the recent loading. The sun has enough punch to weaken this recent snowfall. Avoid the big slopes for now; especially on shallow, rocky and unsupported terrain. Cornices pose a threat to terrain below. NORTH COLUMBIA REGION WEATHER: Variable snowfalls have added 20-40 cm of storm snow on the weekend. This sits on top of last week^Òs big storm slab which totalled 60-80 cm. Temperatures in the alpine have cooled over the weekend. Moderate to strong winds have redistributed and stiffened the new snow. The cool showery pattern will persist through Thursday with a weak trough Wednesday enhancing the flurries. SNOWPACK: The top 20-60 cm of the snowpack is moist up to the 2000m elevation. The snowpack remains fragile, with numerous shears observed within the storm snow Sunday. Wind slabs have been reactive at treeline and in the alpine. An easy to moderate shear persists down 75-120 cm on the old mid February surface hoar. The surface layers will weaken on sunny aspects as the day warms. Expect a crust to form in the moist layers which will increase strength below treeline. Fragile cornices have grown large and are ready to drop. AVALANCHES: The avalanche cycle continued through the weekend with numerous size 2.0 to 3.5 avalanches from natural, skier, and machine triggered events. Slabs triggered in the storm snow have stepped down to the November crust and even to ground in some events. One observer remotely triggered five separate size 2 slabs 60 cm deep while digging at a snow profile site at a safe location! FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 19th) ALPINE - High TREELINE - High BELOW TREELINE ^Ö Considerable TRAVEL ADVISORY: A huge load has recently been added to the snowpack and this will take some time to equalize its tension. Deep slab potential remains waiting for the right trigger. Powder snow is a powerful lure but continue to choose safer terrain until the snowpack strengthens. Statistics prove that the most common time for serious avalanche accidents is right after a big storm. SOUTH COLUMBIA REGION WEATHER: The epic storm last week dumped 100 cm of storm snow in the alpine. Snow squalls dropped another 20 cm of over the weekend. Temperatures cooled somewhat while winds remained moderate to strong. The cool showery pattern will persist through Thursday with a weak trough Wednesday enhancing the flurries. Snow squalls will pick up above 1000m in the afternoons from heating. SNOWPACK: The snowpack remains fragile with numerous easy shears observed within the storm snow Sunday. Easy to moderate shears persist down 75-150 cm on the old mid February surface hoar and facet layer creating a concern. These weaknesses will persist, especially at shallow snowpack sites in the Purcells. Wind slabs have been reactive at treeline and in the alpine. While the storm snow is strengthening, the shear on the surface hoar will do so much more slowly. The surface layers will warm and weaken on sunny aspects as the day progresses. Expect a crust to form as temperatures fall in the moist layers increasing strength. AVALANCHES: The avalanche cycle continued over the weekend. Slabs were triggered by vehicle, skier, explosive and natural triggers. Unfortunately, one avalanche claimed two lives on Monday. FORECAST OF AVALANCHE DANGER UP TO WEDENSDAY EVENING (March 19th) ALPINE - High TREELINE - High BELOW TREELINE ^ÖConsiderable TRAVEL ADVISORY: We^Òve all been forced to stay out of the mountains while the storm pounded us last week. Now sunshine and powder look inviting but the danger remains high. Situations like this often lead us into decisions that in hindsight appear to have been foolhardy. The most common time for an accident to occur is in the first few days after a big storm. KOOTENAY BOUNDARY REGION WEATHER: Heavy snow occurred in the alpine last week, with heavy rain below 2000m. This was followed by snow squalls that added another 15-20 cm on the weekend. Temperatures cooled somewhat over the weekend while winds remained moderate to strong. The cool showery pattern will persist through Thursday. Snow squalls will pick up above 1000m in the afternoons from daytime heating. SNOWPACK: The surface layers will warm and weaken on sunny aspects as the day warms. Numerous easy to moderate shears were reported in the storm snow. The snowpack is still showing signs of instability in the old weak layers of buried surface hoar, crusts and facets. Moderate shears are still reported at the mid February surface hoar layer. Cornices have grown quickly and will remain fragile. Expect a crust to form in the moist snow when things cool down increasing its strength. AVALANCHES: On solar aspects, numerous sluffs were reported in the isothermal surface snow. Slabs size 2 to 3 were observed just north of the area from natural and skier triggers. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 19th) ALPINE - High TREELINE - High BELOW TREELINE ^ÖConsiderable TRAVEL ADVISORY: The natural signs of serious avalanche danger are beginning to disappear in these few days after the huge storm. This will lead some to conclude that things are now alright. Some will likely even get away with some rather bold lines in the next few days. A cautious attitude and giving all serious avalanche terrain a wide berth is much less likely leave you among the victims of a serious avalanche this week. SOUTH ROCKIES REGION WEATHER: The epic snowstorm last week, which dumped up to 90 cm of dense storm snow in the alpine and brought rain at low elevations, is still the biggest factor in the overall picture. Convective flurries added 5-15 cm more snow over the weekend. Temperatures were mild. This pattern should continue through Thursday with the freezing level hovering at 1300m. SNOWPACK: Last week^Òs stiff slab up to 100 cm thick remains sensitive to natural and human triggers. Sunny slopes will weaken during the day since the sun packs more punch this time of year. Cooling will add some strength below treeline as a melt freeze crust forms overnight on the moist surface. Cornices have grown large in the past week. AVALANCHES: Numerous size 2 to 3 avalanches have been observed over the weekend to the North. Ski cutting was producing wet size 1 to 2 avalanches in the Lizard Range Sunday. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 19th) ALPINE - High TREELINE - High BELOW TREELINE ^ÖConsiderable TRAVEL ADVISORY: Avoid any avalanche terrain that has not recently avalanched, as it is potentially very sensitive to human triggering. Ensure your route is not threatened by cornice fall. The isothermal snowpack below treeline will make travel miserable where the crust has not formed.