Avalanche Forecast
Issued: Mar 6th, 2020 1:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Loose Wet.
ghelgeson,
Avalanche Canada
The sun is coming out for the first time after a stormy period which will make wind slabs and cornices more sensitive to failure. Give corniced slopes a wide berth and watch for loose wet avalanches on south and west facing slopes.
Summary
Confidence
Weather Forecast
Lots of sun expected this weekend.
FRIDAY NIGHT: Light west/southwest wind, freezing level at valley bottom, 2 to 5 cm of snow possible.
SATURDAY: A few clouds, light variable wind, freezing level at valley bottom, no significant precipitation expected.
SUNDAY: Clear sky in the morning, scattered cloud cover after lunch, moderate west/northwest wind, no significant precipitation expected.
MONDAY: Clear sky in the morning, increasingly cloudy, building to broken cloud cover after lunch, strong west/southwest wind, no significant precipitation expected during the day, potential for 5 to 10 cm Monday night.
Avalanche Summary
As we head into the weekend we expect the strengthening March sun to be the main driver of avalanche hazard. Although the air temperature will still be below freezing, the sun could bring on a wave of loose wet avalanches on solar (south and west) aspects, it could also weaken cornices to the point of failure.
On Wednesday control work in the pine pass produced avalanches up to size 3.5 that were running on the late February crust which is about 70 cm below the surface.
On Tuesday a natural avalanche cycle included storm & wind slabs up to size 3 in wind loaded alpine terrain. Natural avalanche activity was likely extensive last weekend but poor visibility limited observations.
Snowpack Summary
The region picked up 7 cm (Renshaw) to 15 cm (Kakwa, Core Lodge & Link Creek) Thursday into Thursday night and this snow hasn't seen much wind yet. This new snow rests on wind effected snow as there's been 40 to 100+ cm of storm snow that fell over the last 10 days, this older snow was heavily affected by west/southwest wind
There are a couple of crusts beneath recent storm snow including a rain crust below 1200 m and sun crusts on south and west facing slopes.
The lower snowpack is strong and well-bonded in many parts of the region. However, given the large extent of the region it remains important to understand snowpack conditions in your local riding area.
The Pine Pass area has a layer of surface hoar roughly 100 cm below the surface that was a problem around treeline elevations in mid-February, but appears have gained strength since then.
The eastern slopes of the Rockies have many shallow rocky slopes that could harbour weak basal facets.
Cornices have grown large and should be given wide berth, especially if you're travelling on ridge lines.
Terrain and Travel
- Cornices become weak with daytime heating, travel early on exposed slopes.
- Be careful as you transition into wind affected terrain.
- Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
- Rocks will heat up with daytime warming and may become trigger points for loose wet avalanches
Problems
Wind Slabs
As the cold snow feels the sun for the first time this weekend it could make wind slabs just a bit more sensitive to human triggering. The sun will also allow cornices to heat up, further weakening them, potentially to the point of failure. Even when you're in the shade, overhead cornices may be receiving strong sun which can catch us off guard.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
As the fresh snow sees the sun for the first time a round of loose wet avalanches is expected. This should be confined to solar aspects (those that face south & west). The steeper the slope, the more activity you're likley to see.
Aspects: South, South West, West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 9th, 2020 5:00PM
