 double-double seeking, snow-chasing, short-cutting, vertical feet collector
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Posted - 02/24/2004 : 07:44 AM
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SOUTH COAST
Weather: The ridge of high pressure that sat over the region last week has finally begun to move out on the weekend. This has allowed some cloud to move in at mid elevations, putting a slight kink in the sun worshipers routine this week. Although mountaintop areas may remain in sunshine, expect the cloud to persist at mid and lower elevations until Wednesday at least. Winds will pick up to 20-40 km/hr out of the south, and occasional snow showers will occur above 1300m, with rain below.
Snowpack: A significant layer of surface hoar has formed during the clear weather, but this has been burned off on solar aspects. On most of the other aspects, recent winds have knocked it over as well, but in sheltered areas pockets of surface hoar up to 1.5cm thick may get buried under the light new snows.
Avalanche Activity: As the cloud invaded, natural avalanche activity ceased. There remains some potential for south facing slopes to release at higher elevations if start zones are above the cloud and in direct sunshine.
Forecast of Avalanche Danger Up To Wednesday Evening (February 25, 2004)
Alpine – MODERATE
Treeline – MODERATE
Below Treeline – LOW
Travel Advisory: Keep cornice fall in mind this week, particularly from any sunny high elevation ridges that may be hidden from view above the clouds. Remain aware that there are still occasional pockets of weak snow waiting for a human trigger out there. Generally, this is a good time to get out and not throw caution completely to the wind but enjoy some of those trips and activities that are best saved for moderate danger periods.
NORTH COLUMBIA
Weather: A ridge of high pressure headed east out of the region finally on Sunday night, allowing some cloud to creep into the area from the coast. Daytime temperatures cooled off Monday to near zero degrees. Winds remained light out of the south quadrants. The weather forecast calls for spotty snow showers throughout the week, with winds increasing to a peak of 50 km/hr out of the SW by Tuesday night.
Snowpack: Most areas have a crust formed on solar aspects. The layer of surface hoar buried February 14th is down 20 to 50 cm, depending on location, as the last snowfall event was highly variable. Since the forecast calls for further variability in snowfall, accompanied by wind transport, expect this situation to get even more complicated. The buried surface hoar is usually absent on south aspects, but well preserved on other aspects. The mid and lower snowpack is strong.
Avalanche Activity: Natural and cornice related activity, as well as human triggered events, continued to be reported, most in the size 1.5 to 2.5 range but with one size 3 near Blue River. Activity decreased to size 1 primarily from human and cornice triggers Monday due to the cooling. Expect the potential for human triggering to persist in pockets as the new snow falls and is transported by the wind.
Forecast of Avalanche Danger Up To Wednesday Evening (February 25, 2004)
Alpine – MODERATE areas of CONSIDERABLE*
Treeline – MODERATE areas of CONSIDERABLE*
Below Treeline – MODERATE
Travel Advisory: *The primary factor in identifying areas of Considerable danger will be the amount of load over the buried surface hoar layer, particularly in areas where route finding may take you near convex terrain features on north or east aspects. Sledding on southerly aspects should be quite enjoyable, with a surface crust for good traction and much less likelihood of buried surface hoar being found on that aspect. If the clouds disappear and the sun comes out for a period of time mid day, this aspect may no longer be the best place to be.
SOUTH COLUMBIA
Weather: After a great taste of spring, clouds rolled into the region Monday as the ridge of high pressure moved off to the east. Daytime temperatures dropped to below zero at all but valley bottoms, and overnight lows are expected to moderate after plunging to as low as -24 under clear skies on the weekend. Some patchy snowfall is in the weather forecast, with winds picking up to 25-50 km/hr by Tuesday as well.
Snowpack: A layer of surface hoar buried February 14th is still the primary concern. The amount of snow above the layer varies, but in most areas it is still expected to become reactive if enough new snow arrives in the next few days. Below the Valentines Day layer, a layer of facets from early January is still identifiable but has not been a factor in any observed releases lately. The mid and lower snowpack are strong, except in the Purcells, where shallower snow depths have allowed colder weather to erode some strength.
Avalanche Activity: Avalanche activity was occasional on the weekend, and was further reduced Monday with the drop in temperatures. Some natural and human triggered events were still reported Monday. Nothing larger than size 1 occurred after the cooling Monday, except a size 2 skier triggered event near Invermere.
Forecast of Avalanche Danger Up To Wednesday Evening (February 25, 2004)
Alpine – MODERATE
Treeline – MODERATE
Below Treeline –LOW
Travel Advisory: If more snow arrives than was forecast, expect the possibility that the Valentines Day layer of buried surface hoar may wake up with surprising vigor. Baring that occurrence, the primary situation to watch out for is human triggering from steep shallow snow zones, particularly on north aspects where the buried surface hoar is most prevalent.
KOOTENAYS
Weather: The Kootenay Boundary region enjoyed some of the sunshine it is famous for on the weekend, but clouds will begin to invade as the ridge of high pressure moves eastward. The weather forecast calls for winds to pick up to as much as 50 km/hr in the alpine by Wednesday. Temperatures will cool to near zero in the daytime. Snowfall will occur by mid week as bands of moisture pass over and some chance exists for moderate amounts of storm snow to accumulate as a result.
Snowpack: A layer of surface hoar awaits burial on all but south aspects. A layer of surface hoar buried on Valentines Day is just waiting for additional load and that’s what is in the weather forecast. The Valentines Day layer is down 10-20cm on most aspects, although it may be absent on southerly aspects where it was destroyed by the sun. The mid and lower snowpack is relatively strong.
Avalanche Activity: Some smaller natural events were reported earlier in the week, but nothing recent.
Forecast of Avalanche Danger Up To Wednesday Evening (February 25, 2004)
Alpine – MODERATE, becoming CONSIDERABLE by Wednesday
Treeline – MODERATE, becoming CONSIDERABLE by Wednesday
Below Treeline – MODERATE
Travel Advisory: The key factor mid week will be how much snow we actually get. With the surface hoar instability that will develop just under the new snow interface, and the similar weak layer buried Valentines Day, it may not take much. The potential for propagation may be quite significant if the lower layer fails. Although south aspects may not have the same potential for human triggering, any direct sunshine may cause the new snow to fail naturally.
SOUTH ROCKIES
Weather: The weather has been warm and pleasant, with daytime highs above zero and winds light out of the SW. The weather forecast calls for cloud to begin spreading into the region Tuesday, with winds picking up significantly. By Wednesday, the region may see some light snowfall developing as well
Snowpack: Solar aspects have been baked in the sun lately, with some shallow rocky areas becoming near isothermal in the afternoons. A layer of surface hoar was buried February 14th, and this layer is still weak, although it has gained some strength on the weekend. Any areas with 30cm or more of snow above this layer are the most reactive. A second weakness can be found down about 70cm in some areas, but in general the mid and lower snowpack are stronger this year than in many winters.
Avalanche Activity: Explosive and human triggering continues to occur on the Valentines Day buried surface hoar. These releases are predominantly on North and East aspects with start zones around the 2000m range. With further direct sunshine, steep southerly aspects at lower elevations may begin to release naturally.
Forecast of Avalanche Danger Up To Wednesday Evening (February 25, 2004)
Alpine – MODERATE areas of CONSIDERABLE*
Treeline – MODERATE areas of CONSIDERABLE*
Below Treeline – MODERATE
Travel Advisory: The areas of considerable danger will be found in two places. *The most likely is northerly aspects, particularly at elevations of 2000m and above. *The second will be low elevation southerly aspects in the afternoons, once they have been baking in the sun. The cool nights may have been eroding the strength in shallow snowpack areas, so be conscious of these as likely zones for human triggering to occur. Don’t forget cornice fall as you choose your lunch spot
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February 23 Canadian Avalanche Association PAB
