Avalanche Forecast
Issued: Mar 16th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Cornices and Loose Wet.
mconlan,
Avalanche Canada
It is possible that riders could trigger wind slabs in steep terrain. Look for signs of instability in your riding area, such as recent avalanche activity.
Summary
Confidence
Weather Forecast
TUESDAY NIGHT: Partly cloudy, 10 to 20 km/h southwest wind, alpine temperature -5 C.
WEDNESDAY: Increasing cloud with afternoon flurries, accumulation 1 to 3 cm, 20 to 30 km/h south wind, alpine temperature -4 C, freezing level 1500 m.
THURSDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 40 to 60 km/h southeast wind, alpine temperature -3 C.
FRIDAY: Cloudy with snowfall, accumulation 20 to 40 cm, 40 to 60 km/h south wind, alpine temperature -6 C.
Avalanche Summary
Cornices were triggered by explosives on Monday and Tuesday, releasing large chunks that could kill a person. Small to large (size 1 to 2.5) slabs were triggered by skiers, explosives, and naturally on Monday within the recent 10 to 20 cm of storm snow.
There's evidence of some large avalanches in the past week around the Whistler area, including near Mt. Fee (see here and here) and last week on Mt. Fissile in the Whistler backcountry. These avalanches may be due to extensive wind loading, but they may also be associated with isolated weak snow from earlier this season.
Snowpack Summary
Wind slabs may linger in steep, lee terrain features at treeline and alpine elevations from Sunday's 15 to 20 cm of snow with extreme southeast wind. The wind slabs could be substantially thicker immediately adjacent to ridges from rapid snow loading during the storm. Expect to find a hard melt-freeze crust on sun-exposed slopes and on all aspects below around 1500 m. The crust may weaken into moist snow on sun-exposed slopes if sunny skies prevail. Along ridgelines, cornices are large and will weaken with daytime warming.
Around 100 to 300 cm of consolidated snow may overly sugary faceted grains formed earlier this season. These layers are expected to be spotty around the region and we haven't received conclusive evidence of them being the culprit of avalanche activity. That being said, it is possible they may be associated with a few recent large avalanches around the Whistler area.
Terrain and Travel
- Carefully evaluate steep lines for wind slabs.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Extra caution is needed around cornices under the current conditions.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
Problems
Wind Slabs
Riders could still trigger wind slabs from recent snow and extreme southeast wind. There's been reports of large avalanches triggered by riders and cornices in the past week, so use particular caution in committing terrain with high consequences.
Aspects: North, North East, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are large and looming along many ridgelines. They may be weakening with progressive days of relatively mild air temperature and sunny skies, increasing the likelihood of them releasing naturally or from the weight of a person.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Wet loose avalanche activity is possible if sunny skies prevail. Use caution on steep, sun-exposed slopes during the heat of the day.
Aspects: South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 17th, 2021 4:00PM
