Avalanche Forecast
Issued: Mar 9th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
A swift uptick in winds should put increasing wind slab hazards at top of mind for Tuesday. Keep your guard up around steep, sheltered slopes where persistent slabs are a lingering concern.
Summary
Confidence
Weather Forecast
Monday night: Clear. Light southwest winds increasing to moderate by morning.
Tuesday: Becoming cloudy with increasing flurries bringing 5-10 cm of new snow by end of day, continuing but easing overnight. Moderate to strong southwest winds. Alpine high temperatures around -6.
Wednesday: Decreasing cloud with final flurries leaving up to 5 cm of new snow. Light northwest winds. Alpine high temperatures around -8.
Thursday: Mainly sunny. Light west winds. Alpine high temperatures around -10.
Avalanche Summary
Reportd from Saturday and Sunday showed numerous natural, skier triggered and explosives controlled storm slab avalanches reaching size 1 to 2 on all aspects between 1900 and 2100 m. A gradual trend toward artificial triggers is evident in reports, as well as improving visibility allowing observation of earlier releases. These avalanches were generally limited to the depth of new snow, reaching up to 40 cm deep.
On Friday, a few small (size 1.5) avalanches released on the February surface hoar layer described in our Snowpack Summary. They occurred on northerly aspects around 2000 m and were 20 to 30 cm deep.
Over the past two weeks, small to large (size 1 to 2) avalanches have released on this surface hoar layer. They have most often released between 1800 and 2300 m on northwest to east aspects. This trend is suspected to continue as this layer slowly gains strength.
Snowpack Summary
Around 10-15 cm of snow fell in the west of the region and 20 to 35 cm in the east of the region over the weekend. Storm slabs are likely developing as the snow consolidates. The wind remained light to moderate from the southwest, so wind slab formation may be limited to immediate lee features.
Recent snowfall has been loading a touchy layer of feathery surface hoar crystals from late February that is found 30 to 60 cm deep. The layer is most commonly found in open trees (e.g. in this MIN) or sheltered terrain around upper below treeline, treeline, and lower alpine elevations. Check out the latest forecaster blog that offers a deeper dive into these conditions.
The remainder of the snowpack is strong and well-settled.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Watch for avalanche hazard to increase throughout the day.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Wind Slabs
Light new snow amounts and elevated southwest winds are expected to layer touchy new wind slabs over leeward (north to east) terrain in exposed areas on Tuesday. This problem will increase over the day, with wind redistribution peaking in the afternoon.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Around 30 to 60 cm of snow overlies a weak layer of surface hoar. The layer has been most problematic on northwest to northeast aspects between 1600 m and 2300 m, but the layer may exist on all aspects and at all elevations. Assess the layer prior to committing to avalanche terrain or adopt a conservative mindset to avoid the problem.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 10th, 2020 5:00PM
