February 24, 2003 SOUTH COAST REGION WEATHER: A wave of cold, northern air passed over the Coast Range this weekend leaving behind 10-30 cm during its passage. In the wake of this front, clear skies and cold temperatures (-20^Òs) and NE winds are now firmly established over the region. Look for this condition to persist for several days, although we can expect some moderating in temperatures by later on Tuesday. No snowfall is expected in the next 48 hours. SNOWPACK: New snow followed immediately by cold air is a good omen for the snowpack ^Ö this has contributed significantly towards a good bond between recent storm snow and the underlying surfaces. Isolated windslabs in the upper 30 cm of the snowpack may still be found in leeward terrain above treeline, but this condition is no longer widespread. Now buried anywhere from 30-50 cm is a layer of surface hoar ^Ö although somewhat isolated, you can expect to see this instability most pronounced at treeline where enough snow overlies the layer for avalanches to occur. Finally, a continuing reminder to be alert for shallow snowpack areas, where facets near a crust formed on Jan 26 have produced several avalanche over the last week. AVALANCHES: Several small, isolated windslabs in the upper 20 cm of the snowpack were observed on Sunday, and on Friday a 40 cm deep fracture line released on the Jan 26 facet/crust combo. These avalanches were all observed between 1700 and 2200 meters. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (FEB 26) ALPINE: MODERATE TREELINE: MODERATE BELOW TREELINE: LOW TRAVEL ADVISORY: With generally improving snow stability over the last few days, here are a couple of tricks to help you with decisions. On your way up the hill, cover as much ground as possible ^Ö attempting to observe various aspects and elevations. Dig a couple of test pits on different aspects, looking for the weak layers noted above ^Ö see how strong the bonds between layers are. Use the clear skies to look around for recent avalanche activity. Finally, when choosing your descent, select terrain where you feel confident in the snowpack and your party can all easily manage the challenges. NORTH COLUMBIA REGION WEATHER: Over 100 cm of snowfall in the last 7 days! The passage of an arctic front on Friday left behind up to 30 cm of cold, dry snow on the surface. In the wake of the cold front, clear skies, light NE winds and cold temperatures (-10 to -20) now have a grip on the region. Don^Òt expect much change over the next 48 hours, except perhaps some clouds and minor flurries for late Wednesday. No significant accumulations are expected. SNOWPACK: Last week^Òs big dump of snow had the avalanche danger climbing rapidly into the weekend. With 60-80 cm of settled snow now resting on a nasty layer of surface hoar ^Ö avalanche activity has been widespread. Strong winds in alpine regions have also produced sizable windslabs - together with the surface hoar problems at treeline and lower, all elevations are now suspect. With the cold air now blanketing the region, natural avalanche activity has relented, replaced by many slides triggered by humans and explosives. AVALANCHES: A widespread avalanche cycle occurred on Friday and Saturday. A good look around under blue skies on Sunday revealed countless avalanches down, and explosive testing released many more. Most are failing on the surface hoar layer down about 80 cm. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (FEB 26) ALPINE: HIGH TREELINE: HIGH BELOW TREELINE: CONSIDERABLE TRAVEL ADVISORY: Any travel in the mountains this week needs to be done with great care. It^Òs certain that many steep slopes can be triggered by humans, at all elevations. Avoid crossing avalanche terrain unless you^Òre confident in the snowpack. Confidence should be gained by facts, not by the blue sky. Watch for telltale signs of instability (cracking, settling), dig down and look at the surface hoar problem, and use the clear skies to have a good look around you. Accidents are common in the week following surface hoar burial ^Ö remember this. SOUTH COLUMBIA REGION WEATHER: Last weeks big dump of snow was blown to smithereens on Saturday, as a cold front passed over the region leaving 10-20 cm of cold and dry snow on the surface as a final treat. Cold air now blankets the region, with valley bottoms down in the -20^Òs and alpine temperatures slightly warmer. Clear skies and light NE winds prevail. Gradual warming is forecast through the week, but only light amount of precipitation is coming for Wednesday. SNOWPACK: Over 100 cm of snow fell over the last 7 days! This immediately created a significant avalanche danger, as all this new snow overlies a nasty layer of surface hoar that in places below treeline was several centimeters thick! Very strong winds on Saturday also produced significant windslabs in alpine areas - so all elevations were suspect over the weekend. Cooling temperatures which normally help to stabilize the snowpack, have not done much this time around. Many large avalanches continue to be observed despite the cold air. AVALANCHES: Dozens of large avalanches up to size 3.5 were reported right through the weekend, mostly failing as windslabs from last week, or on the surface hoar layer down 60-80 cm. Several very large avalanches were recorded on glaciated terrain, with the entire snowpack sliding leaving a big piece of bare ice exposed. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (FEB 26) ALPINE: HIGH TREELINE: HIGH BELOW TREELINE: CONSIDERABLE TRAVEL ADVISORY: Careful times in the mountains, once again this season. Seems to be a bit of a theme don^Òt you think? The potential to trigger a sizeable avalanche is significant. Look for clues like cracking and settling of the snowpack, and more obvious ones like recent avalanche activity. Treat all avalanche terrain with suspicion and only flirt with conservative and non committing slopes ^Ö don^Òt find yourself undercutting big slopes. Any avalanche terrain you need to cross should be approached from the top whenever possible. Accidents are most common in the weeks following big cycles as our confidence grows ^Ö keep this in mind. KOOTENAY BOUNDARY REGION WEATHER: Last week^Òs snow accumulations of about 60 cm finished over the weekend with the passage of a cold front. This front left behind 10-20 cm of light snow, followed by clear skies and cold air. Temperatures on Monday started at -20 and are expected to climb -8 or so. The NE flow of cold air is expected to persist through the middle of the week, with gradual warming forecast. Additional snow accumulations are not anticipated. SNOWPACK: Despite numerous instabilities lurking in the snowpack, backcountry travelers should focus this week on the recent storm snow and its suspicious bond to the layers below. Up to 80 cm of snow now sits on a very weak layer of surface hoar, buried Feb 15. Just below this is a thin layer of facets formed around a raincrust from Jan 26. Last week^Òs storm has overloaded these layers and produced numerous avalanches on both of these weaknesses ^Ö improvement will be slow with the onset of cold temperatures. Expect avalanches to continue being triggered through the coming days. AVALANCHES: Natural activity has subsided with the cold temperatures, but avalanches continue to be triggered by humans and explosives. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (FEB 26) ALPINE: HIGH TREELINE: HIGH BELOW TREELINE: CONSIDERABLE TRAVEL ADVISORY: Heads up this week, lots of unstable slabs are hanging, waiting to be triggered. Several skier triggered events were noted in the Nelson area over the weekend. Not much is expected to change into this week ^Ö so approach all avalanche terrain with uncertainty. Use the clear skies to your advantage and have a good look around ^Ö note the avalanche activity and any other clues you observe while traveling. Rutchblock testing is a good technique for the current conditions. SOUTHERN ROCKIES REGION WEATHER: Last week^Òs big dump of snow was followed over the weekend by the passage of a cold, arctic front. This front left about 10 cm of light snow in most regions ^Ö and now cold temperatures (-10 to -20), clear skies and light NE winds are established for the next few days. Expect a slight warming trend as the week progresses, but no significant snowfalls are anticipated. SNOWPACK: A lot of variation in snowpack through this region (Crowsnest, Waterton and Fernie). Generally speaking ^Ö 60-80 cm of snow fell over the past 7 days everywhere. This new snow overlies a very weak layer of surface hoar down about 60 cm, and is continued to produce avalanches easily with human triggers. Avalanche activity appears to have dropped off since the invasion of the cold air ^Ö but don^Òt let this boost your confidence as all the right ingredients for avalanches remain. AVALANCHES: Observer reports of avalanche activity varied throughout the region form slab avalanches running on buried surface hoar at treeline near the continental divide, to only small avalanches in the Fernie region. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (FEB 26) ALPINE: CONSIDERABLE TREELINE: CONSIDERABLE BELOW TREELINE: CONSIDERABLE TRAVEL ADVISORY: This will be an interesting week in the world of avalanches. Coming out of a big snowfall event and trying to determine where to ride and where not to ride is difficult. It^Òs easy to gain confidence under blue skies but really, confidence should only come from facts. Observe the snow as you travel, looking for clues like cracking and settling. Dig a few pits and identify the weak layers. Use the good visibility to take note of any avalanche activity. Stick to conservative and non committing slopes until you have confidence. Expect human triggering to be probable.