Avalanche Forecast
Issued: Jan 18th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
shorton,
Avalanche Canada
Variable wind has made wind slab avalanches possible at upper elevations, especially in northern parts of the region.
Summary
Confidence
Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.
Weather Forecast
MONDAY NIGHT: Clear skies, moderate ridgetop wind from the north, treeline temperatures drop to -8 C.
TUESDAY: Clear skies in the morning then increasing cloud in the afternoon, southwest ridgetop wind building to strong, treeline temperatures around -5 C with freezing level around 1000 m.
WEDNESDAY: A trace of snow overnight then mix of sun and cloud during the day, light west wind, treeline temperatures around -6 C.
THURSDAY: Mostly cloudy, light southwest wind, treeline temperatures around -6 C.
Avalanche Summary
Over the weekend a few natural wind slab avalanches and cornice falls were reported in the northern parts of the region (up to size 2).
A widespread natural avalanche cycle size 2-3 occurred throughout the region during a storm last week. Avalanche character was predominantly storm slab in the snowy north of the region and wet loose or glide slab in the rainy south. Northwest of Pemberton, several stepped down to buried weak layers resulting in very large (size 3-4) persistent slab avalanches.
Snowpack Summary
In the south of the region, fluctuating freezing levels during the last storm have resulted in a crust to ridgecrest. At upper elevations, 5-10 cm of dry snow has been blown around by the wind, exposing the crust in some areas and building wind slabs on top of it in others. The lower snowpack is well settled.
In the north, upper elevations are extensively wind affected. A widespread surface crust exists below 1600 m. A melt-freeze crust from early December is found around 200 cm deep in the snowpack. This crust may have sugary faceted grains sitting above it. This persistent weak layer is most prevalent northwest of Pemberton where large avalanches have failed on this interface recently.
Terrain and Travel
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Conditions may have improved, but be mindful that deep instabilities are still present.
Problems
Wind Slabs
Shifting wind has deposited recent snow into deeper slabs on leeward slopes making it possible to trigger wind slab avalanches. Cornices have also grown large, saggy, and fragile.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A problematic layer consisting of sugary faceted grains over a crust may be found around 200 cm deep. The likelihood of triggering an avalanche at this interface has reduced, but the consequence of doing so remains high.
This problem is most prominent along the northwestern border of the region and nonexistent in the south.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 19th, 2021 4:00PM
