Avalanche Forecast
Issued: Feb 9th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Loose Wet and Wind Slabs.
ldreier,
Avalanche Canada
Warm temperatures and rain continue to weaken the snowpack. This will increase the likelihood of triggering avalanches on the buried weak layer. These avalanches can be triggered from a distance away, be mindful of slopes above and adjacent to you.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
WEDNESDAY NIGHT: Cloudy, 5 to 10 cm new snow and rain at lower elevations and the lower alpine, moderate to strong west wind, alpine temperature +1 C, freezing level 2300 m.Â
THURSDAY: Mix of sun and cloud, trace of new snow, light to moderate west wind, alpine temperature 0 C, freezing level slowly dropping to 1500 m.
FRIDAY: Sunny, light to moderate northwest wind, alpine temperature -5 C, freezing level 1200 m.
SATURDAY: Mostly sunny, light west wind, alpine temperature -3, freezing level 1500 m.Â
Avalanche Summary
On Tuesday, skiers triggered small slabs on the buried weak layer with surface hoar. One was triggered from a distance away.
On Monday, wet loose avalanches below 1000 m were observed. Observations were limited due to visibility.
On Sunday, two natural large avalanches of size 2-2.5 were observed in steep terrain on north and east aspects in the alpine. Several large avalanches released on sun exposed steep slopes. Riders triggered a large size 3 avalanche in the south of the region.
Snowpack Summary
Accumulations during the day Wednesday and Wednesday to Thursday night will total around 10 to 30 cm of snow up high. At lower elevations and the lower alpine the precipitation will fall as rain with increasing temperatures. Accumulations will add to the previous storm which brought around 30 to 50 cm of snow. The snow formed wind slabs in lee terrain features at treeline and in the alpine from strong southwest wind and storm slabs in wind sheltered areas. The snow surface will be moist or wet at lower elevations and the lower alpine and likely form a crust when temperatures slowly drop during the day on Thursday.
The snow will be particularly touchy where it loaded a weak layer of surface hoar crystals. This layer is likely anywhere from 50 to 100 cm deep. Reports suggest that the surface hoar is most prominent in sheltered openings at and below treeline but could extend into wind-sheltered terrain in the alpine. Example terrain features to treat as suspect include the lee side of protected ridges, openings in the trees, cut blocks, and burns. On south aspects, a melt-freeze crust may exist instead of surface hoar.
The lower snowpack is generally strong and well-bonded.
Terrain and Travel
- Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Persistent Slabs
The recent snow loaded a buried weak layer of surface hoar crystals. The layer may be found around 50 to 100 cm deep and is most prominent in areas sheltered from the wind at and below treeline. Example terrain features to particularly treat as suspect include the lee side of ridges, openings in trees, cut blocks, and burns. Triggering this layer from a distance away is a concern, watch out for adjacent and overhead slopes.
The buried weak layer was reported to be very active in the Blue River area at all elevations and in the Wells Gray area below treeline. And it is present up to treeline at Mica Mountain and around Valemount.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Wet
Warm temperatures and rain at lower elevations and the lower alpine will continue to weaken the snowpack. Temperatures will only slowly decrease during the day on Thursday.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
Moderate to strong southwest and west wind redistributed 15 to 30 cm new snow and formed fresh wind slabs at higher elevations in lee terrain features.
Cornices might become weak with the warm temperatures. The additional load of a cornice failure can trigger slabs on the slope below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 10th, 2022 4:00PM
