January 20, 2003 SOUTH COAST REGION WEATHER: The ridge of high pressure covering most of BC managed to deflect any storms that might have come this way. A nice weekend with some warm air up high gave no new snow and temperatures ranging from 0 to -5. The ridge will break down at the start of this week and thankfully we return to a westerly flow with some moisture. Not much until mid week, just bands of flurries until Wednesday when it looks like more snow. SNOWPACK: No new snow to report over the last few days, but above freezing temperatures in some locations have melted and then refrozen the surface layers, resulting in suncrust in isolated S and W facing terrain. The main focus of concern in the snowpack is the presence of unusual persistent instabilities lower in the snowpack ^Ö this is not typical on the Coast. Surface hoar buried on Christmas Day is now 75-100 cm down and continues to be a potential failure plane. A layer of crust and facets from early December remains weak and is down near the base of the snowpack. AVALANCHES: No significant avalanches have been reported over the weekend. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (JAN 22) ALPINE: Moderate TREELINE: Moderate BELOW TREELINE: Moderate TRAVEL ADVISORY: When asking yourself what sort of terrain to enter, remember what an unusual sort of snowpack exists on the Coast this winter. Triggering of deep instabilities such as the ones buried right now is very difficult to predict. Long periods of seemingly stable conditions may pass and then very subtle changes or just the right trigger may bring about large avalanches. NORTH COLUMBIA REGION WEATHER: A generally stable weather pattern persisted over the North Columbias through the weekend, with a ridge of high pressure driving storms up the north coast. Valley cloud and warm air at higher elevations dominated most of the last week, although alpine temperatures remained below freezing. No significant snow has fallen in the last few days. A westerly flow returns mid week with the chance of more snow as moisture comes in off the Pacific. SNOWPACK: Changes to our snowpack have been occurring very slowly lately. With no significant snow to report in the last few days, our focus remains on the persistent instabilities found in the mid and lower snowpack. Surface hoar buried on Christmas Day now sits roughly 50-75 cm below the surface. This layer can be difficult to find and although strength tests indicate an improving trend, it remains a concern. Near the base of the snowpack a weak crust/facet combination from November persists. AVALANCHES: The frequency of avalanches observed has declined, but their size has not. Each day large avalanches continue to be reported in the Selkirks. Tragically, a large avalanche in the North Columbia region occurred on Monday, resulting in multiple fatalities. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (JAN 22) ALPINE: Considerable TREELINE: Considerable BELOW TREELINE: Moderate TRAVEL ADVISORY: During long periods of fair weather and improving stability of the snowpack it is common that we begin to explore steeper places. Remeber that we have two persistent instabilities still producing infrequent but large and dangerous avalanches throughout the region. Route finding and terrain evaluation skills are your best tool right now ^Ö travel in moderate terrain and make conservative decisions based on observations you^Òve made yourself, leaving a margin for uncertainty. SOUTH COLUMBIA REGION WEATHER: The ridge of high pressure that kept BC dry last week continued to block all storms over this past weekend. Valley cloud covered most towns, with clear skies and warmer air making for beautiful weather higher in the mountains. The ridge begins to deteriorate early this week, but don^Òt expect any significant precipitation until mid week, when some more serious snowfall is a strong possibility. SNOWPACK: There are three buried instabilities worthy of note. Just under the surface is the Jan 11 surface hoar layer, responsible for small avalanches in the surface layers but not really acting up all that much yet. 75-100 cm down from the surface is another layer of surface hoar buried on Christmas Day. This layer has been gaining strength, but remains a serious concern as it still occasionally produces large avalanches. Finally, near the base of the snowpack, a very weak crust/facet combination continues to weaken as our snowpack remains shallow. View this layer with caution. These types of instabilities are unpredictable and can produce large avalanches. AVALANCHES: Natural and explosive triggered avalanches up to size 3 continue to be observed. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (JAN 22) ALPINE: Considerable TREELINE: Considerable BELOW TREELINE: Moderate TRAVEL ADVISORY: With so many weak layers buried, it is difficult to predict with certainty if a slope is subject to human triggering. Conservative terrain choices are the best approach. Although the sheer number of avalanches occurring has slowed since early January, the size of the events has not. Very large avalanches are possible under these conditions, so choose your terrain with a view to conservatism. KOOTENAY BOUNDARY REGION WEATHER: A ridge of high pressure over southern BC kept the Kootenay Ranges mostly dry over the weekend. Warmer temperatures in the clear air above the valley fog made for beautiful alpine traveling. No significant snowfalls are expected in the next several days as the ridge of high pressure begins to break down slowly. By mid week BC should return to a southwesterly flow, enhancing the likelihood of more snow. SNOWPACK: A significant layer of surface hoar and facets has formed on top of the snowpack in the last week. Below the surface, our shallow snowpack has some problems, starting with a layer of surface hoar 20-30 cm below the surface. This is the Jan 11 layer. In the middle of the snowpack, roughly 75 cm down is another layer of surface hoar buried on Christmas Day. The Christmas layer remains a concern and has produced a number of large avalanches in the past weeks. Finally, near the base of the snowpack is a crust/facet combination made up of very weak snow, unpredictable and capable of producing large avalanches. AVALANCHES: No significant avalanches were observed over the weekend, but large ones continue to be triggered in adjacent regions. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (JAN 22) ALPINE: Considerable TREELINE: Considerable BELOW TREELINE: Moderate TRAVEL ADVISORY: With all these dangerous layers in the snowpack ^Ö where to go, where to go? Your terrain choices are all important in these conditions. Even the subtlest of convexities could be the unlucky spot where you trigger an avalanche. Avoid unsupported terrain features and 30-45 degree convexities> Stop and regroup in safe places. During winters like this, when it^Òs easy to be complacent in the face of a very weak snowpack, your terrain habits will help define your safety. SOUTHERN ROCKIES REGION WEATHER: Valley cloud with clear skies at higher elevations has dominated the weather on the BC side of this region. Calm and clear weather continues on the Alberta side of the range. On Monday an Arctic front sits on the eastern edge of the Rocky Mountains, mostly over the Prairies. The leading edge of this front could produce some short but intense snowfalls as it passes through. Otherwise no significant snow is forecast until mid week, when it looks good for some moist Pacific air to collide with the arctic air for some real snow. SNOWPACK: The Fernie region and the Crowsnest region snowpacks are quite different ^Ö although they share one characteristic and that is the word WEAK. Both snowpacks have significantly weak facets near the base, with even some depth hoar towards the Crowsnest. With the deeper snow in Fernie, several layers of surface hoar persist in the upper meter of the snowpack and both represent a significant instability. Generally speaking, both snowpacks are loaded with weak layers and it may not take much change to trigger avalanches. AVALANCHES: Only small, sun triggered avalanches were reported over the weekend. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (JAN 22) ALPINE: Considerable TREELINE: Considerable BELOW TREELINE: Moderate TRAVEL ADVISORY: This is an unusual winter and so is the snowpack. Long periods of unchanged weather can lull us into thinking the snowpack is stabilizing, but in reality most professionals are observing it to be getting weaker. Terrain evaluation skills are your best tool to deal with this situation. Avalanches may not occur regularly under these conditions, but when they do they can be large and destructive.