 double-double seeking, snow-chasing, short-cutting, vertical feet collector
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Posted - 02/25/2004 : 11:15 PM
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February 25, 2004
This Forecast Sponsored by Janod Contractors Inc.
South Coast Region
Weather: The unsettled weather of the last few days will continue through Friday as a weak disturbance travels through the region. Weather forecasters expect 5-15 cm of new snow by Thursday morning; however, heavier snowfall amounts in isolated locations are possible. Expect moderate southerly winds with freezing levels near 1500 m Thursday. Friday should be cooler, drier, and possibly even sunnier.
Snowpack: Wind slabs, up to 40 cm thick and reactive to human triggers, exist on lee slopes—primarily NW and N facing. New snow buried a significant surface hoar layer on Monday. This is a sensitive snowpack weakness, although it is somewhat variable in its distribution. Expect it in wind protected areas, especially near treeline where it may form a one cm thick layer. Below this is a second surface hoar layer buried on Valentines Day that snow professionals continue to monitor for strength.
Avalanche Activity: The recent snow and wind led to reports of significant avalanches. Wind slabs up to 40 cm thick released in alpine and exposed treeline areas on NW and N facing slopes. Cross-loaded W and NE facing terrain was also active. Loose snow sloughs on steep terrain were running far and fast.
Forecast of Avalanche Danger Up To Friday Evening (February 27, 2004)
Alpine – Considerable
Treeline – Considerable
Below Treeline – Low
Travel Advisory: How can you identify wind slabs? A slab may look like a pillow where the snow is deep, the snow surface may be smoother than its surroundings, or the colour of the snow may be more chalky or grey than white. You can also detect slabby snow with your skis or board—the snow becomes grabby & cohesive or you may hit a pocket of deep snow. Of course it isn’t helpful to identify a slab mere moments before starting an avalanche; monitoring the wind and noticing visual clues ahead of time are the preferred skills.
North Columbia Region
Weather: Over the past two days there’s been a dusting of snow, light to moderate southerly winds, and continued warm temperatures. Weather forecasters at the Meteorological Service of Canada expect snow accumulations around 10 cm on Thursday & Friday; although short-lived locally heavier snowfalls could develop. Expect warm temperatures and light to moderate (25-40 km/h) southerly winds through Friday.
Snowpack: A weak surface hoar layer buried on Valentines Day is 20-40 cm deep and remains reactive to human triggering. Expected new snow, accompanied by enough wind to concentrate it in lee areas, will increase the stress on this important layer—primarily on northwest through east facing slopes. The deeper snowpack is generally strong; however, a crust/facetted snow combination buried 75 cm deep continues to be watched by snow professionals, especially in areas with thin snowcover.
Avalanche Activity: Accidental triggering of significant avalanches—large enough to bury, injure, or kill a person—continues on northerly facing slopes at treeline elevations. Even gentle slopes, as shallow as 30 degrees, were tripped. The critical weakness is the Valentine’s Day surface hoar, now 20-40 cm deep.
Forecast of Avalanche Danger Up To Friday Evening (February 27, 2004)
Alpine – Considerable
Treeline – Considerable
Below Treeline – Moderate
Travel Advisory: The load (stress) on the surface hoar—which includes the weight of a sled & rider—is important now. Northwest through east facing slopes are key areas to consider tipping the balance between the snow staying where it is, or releasing as a slab. Watch convex slopes, unsupported rolls, and openings around treeline. If it isn’t hot and sunny, southerly slopes should give you good traction and safer riding.
South Columbia Region
Weather: Unsettled weather will continue through Friday. A disturbance will pass through the region Thursday morning and should be followed by a second weaker system Friday. Weather forecasters predict 5-10 cm of new snow by Thursday morning; however, heavier snowfall amounts in isolated locations are possible. Expect moderate southerly winds in the mountains with freezing levels near 1300 m Thursday.
Snowpack: A new layer of surface hoar lies just below the surface, not buried deeply enough to worry about just yet. Surface hoar buried 10-40 cm deep from February 14th is still the primary concern. Easy to moderate stability tests indicate that this layer is susceptible to human triggering. Below the Valentines Day layer in the Purcell Mountains, a layer of facets from early January is still identifiable but has not been a factor in avalanches lately. Also in the Purcells, shallower snow depths are associated with a weak lower snowpack.
Avalanche Activity: Accidentally triggered avalanches occurred on north and east facing slopes at treeline and low alpine elevations. The critical weakness is the Valentine’s Day surface hoar, now 10-40 cm deep. A large avalanche surprised some shredders on a NW slope in a shallow snow area of the Purcells. It released 90 cm deep on a weak layer at the base of the snowpack.
Forecast of Avalanche Danger Up To Friday Evening (February 27, 2004)
Alpine – Considerable
Treeline – Considerable
Below Treeline – Moderate
Travel Advisory: More snow will increase stress on the Valentines layer. Sledders and skiers venturing out should be cautious, especially on N and E slopes where winds may load in snow. Two significant surface hoar layers are in the top 40 cm of the snowpack; this will keep safe mountain travelling challenging for a while.
Kootenay Boundary Region
Weather: Snowfall amounted to 5-10cm on Tuesday. Expect a further 10-15 cm Wednesday night through Thursday morning. Amounts will be highest along the border and less as you move north. Flurries are forecast on Friday. Winds will not be particularly strong, expect winds of 20-40 km/h from the S and SE, but this may be enough to move around the snow in alpine areas. Temperatures will be cool overnight, but rise to near -3 during the day at alpine elevations on Thursday and Friday.
Snowpack: Two important layers of surface hoar are buried in the top 50 cm of the snowpack. One is 15 cm deep and the other is 25-50. Both layers are common on northerly slopes and also on east facing slopes. Easy stability test results on both layers Wednesday point to the likelihood of natural and human triggered avalanches as new snowfall causes additional stress. South facing slopes have crusts in place of the surface hoar layers; the upper crust layer is worth watching as a potential sliding layer for avalanches.
Avalanche Activity: Reports of sizeable human triggered avalanches were received on Wednesday including at least one close call. The avalanches were associated with both surface hoar layers, and occurred on a variety slopes from west through north and east.
Forecast of Avalanche Danger Up To Friday Evening (February 27, 2004)
Alpine – High
Treeline – High
Below Treeline – Considerable (where snow is deep enough)
Travel Advisory: Will the snow overnight Wednesday be enough to wake up the surface hoar layers? That is the big question. The strength of the February 14th layer is variable, but the large size of the crystals, depth of 40-50 cm, and winds capable of moving snow onto the very slopes most susceptible to avalanches lead me to conclude that avalanche danger will be high. Low snow depths below treeline limit avalanche potential there.
South Rockies Region
Weather: We’re teetering back into winter for a couple of days as a small storm brings 5-15 cm of snow for Thursday morning. Snow will last until the early afternoon and taper to flurries that will linger until Friday. Light to moderate south to southeast winds are forecast. Temperatures will remain cool.
Snowpack: The state of the snowpack hinges on the layer of surface hoar that was buried on Valentines Day. This layer produced natural and human triggered avalanches when the amount of snow on top of it reached 30-40 cm in the Fernie area. Stability tests indicate that it is still weak, and we can expect more avalanche activity on this layer. Layers below are less important; although, if you are in a low snowpack area you should be thinking about the effect of the sun beating on south facing slopes – if we get any sun that is.
Avalanche Activity: Avalanche activity swung away from natural avalanches, but avalanches triggered by humans were reported on north, east, and northwest facing slopes. Expect avalanche activity to swing back toward limited natural activity and a greater probability of human triggered avalanches.
Forecast of Avalanche Danger Up To Friday Evening (February 27, 2004)
Alpine – Considerable areas of HIGH*
Treeline – Considerable areas of HIGH*
Below Treeline – Moderate
Travel Advisory: *The forecast snow will tip the balance in areas around Fernie. In some places the snowpack is already very touchy – others are reporting more stable snow. The best advice is to consult skilled locals, and use your backcountry know-how. Less experienced travellers should treat the avalanche danger as High everywhere. |
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February 25 Canadian Avalanche Association PAB
