Avalanche Forecast
Issued: Jan 19th, 2020 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
ghelgeson,
Avalanche Canada
The storm has produced 20 to 65 cm of new snow across the forecast region which rests on a mix of facets and old wind slabs. Conditions will likely remain touchy Monday, stick to simple terrain and avoid overhead hazard as the snowpack adjusts to all the new snow.
Summary
Confidence
Weather Forecast
While the rest of the province heats up, our region should stay cool through the forecast period. The storm will continue to hammer the region through Monday afternoon before a brief break in the action Tuesday. The longer term models show another series of storms starting up Wednesday night that continue through next weekend.
SUNDAY NIGHT: Freezing level around 300 m, strong southwest wind, 8 to 20 cm of snow possible.
MONDAY: Overcast, freezing level around 500 m, moderate southwest wind, 5 to 12 cm of snow possible.
TUESDAY: Scattered cloud cover, freezing level around 400 m, light southerly wind, no significant snowfall expected.
WEDNESDAY: Overcast, freezing level around 500 m, moderate to strong south wind, trace of snow possible during the day.
Avalanche Summary
Observations on Saturday were likely hindered by limited visibility, but there were some natural and human triggered soft slab avalanches up to size 1 that were reported with crowns up to 30 cm in depth.
Control work Friday produced avalanches to size 3 on northwest , north, northeast and east facing slopes between 1900 and 2200 m.
Reports of deep persistent slab avalanches have been trickling in throughout the month. They are associated with a November crust layer near the base of the snowpack which has produced very large avalanches (size 3+) with crown depths of around 2 m. Observations are typically in alpine terrain, on lee or cross-loaded slopes.
Snowpack Summary
As of Sunday afternoon the storm had produced about 20 to 65 cm of snow with the larger totals in the south of the region.
The new snow is resting on extensively wind affected surfaces at and above treeline. In sheltered locations at and below treeline the new rests on up to 20 cm of facets formed during the cold temperatures of last week.
A deep crust from mid November lurks at the base of the snowpack. A couple of recent large avalanches have run on this layer on lee and cross-loaded features high in the alpine. As this storm applies significant new snow loads to the snowpack, these deep layers will feel the stress and we may see some very large avalanches in high places.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Don't let the desire for deep powder pull you into high consequence terrain.
- Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
Problems
Storm Slabs
As of Sunday afternoon the storm has produced 20 to 65 cm of new snow and 10 to 20 cm of snow is expected Sunday Night. At upper elevations this snow rests hard old wind slabs. Out of the wind in more protected features the storm snow rests on up to 20 cm of facets formed during last weeks bitterly cold temperatures. Continued wind generally out of the south is likely forming fresh sensitive slabs in upper elevation features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
This storm is a good test for the mid November crust that lurks at the base of the snowpack. Reports of avalanches on this layer have been few and far between but it has produced large natural avalanches that seem to be most prevalent on alpine lee and cross loaded slopes.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 20th, 2020 5:00PM
