Avalanche Forecast

Issued: Feb 13th, 2019 5:48PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs.

Avalanche Canada ghelgeson, Avalanche Canada

Both storm slabs and loose dry avalanches may remain problematic, especially in more extreme terrain. Very little snow is expected Thursday, but if we get surprised by more than 10 cm, more loose dry avalanches are likely to follow.

Summary

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

The current weather pattern is rather complex, and the weather models are not in agreement. As of Thursday afternoon most of the models show very little precipitation making into the South Coast Inland region. That being said, one model shows up to 10 cm in the south on Thursday and 5 cm to the north. With all of this uncertainty its very difficult to pin down precipitation which is why the ranges are so significant below. Stay tuned for more details. WEDNESDAY NIGHT: Freezing level at valley bottom, around -10 C in the alpine, light southerly wind, no significant snowfall expected.THURSDAY: A few clouds in the morning with cloud cover building through the day, freezing level remaining at valley bottom, light to moderate southwest wind, 1 to 10 cm possible in the afternoon.FRIDAY: Broken cloud cover, freezing level around 500 m, light to moderate southwest wind, 2 to 4 cm of snow possible.SATURDAY: Broken cloud cover, freezing level around 1000 m, light variable wind, trace of snow possible.

Avalanche Summary

On Wednesday loose dry avalanche activity to size 2 was widespread in the south of the region on all aspects.On Tuesday a size 2 natural wind slab was observed on a south facing slope around 2000 m. Loose dry avalanches were also widespread.Wind slab avalanches were widespread over the weekend with two significant incidents being reported on the MIN. We really appreciate that the parties involved posted this information so we can all learn from it. Check out this MIN from the Backside of Heartstrings, and this one from Channel. These incidents show how widespread the wind effect was in the region.

Snowpack Summary

On average, 10 to 20 cm of low density storm snow has fallen over the last few days with wind generally out of the south. Previous to this most recent storm, the region was hit hard by an extreme wind event featuring winds out of the north and northeast which wreaked havoc on alpine and treeline features. So, the fresh snow rests on heavily wind affected snow and stiff old wind slabs. Due to the scouring and wind-loading, anywhere from 0-60 cm of snow sits on a crust on all aspects below 2000m and solar aspects into the alpine. Above 1800 m, recent cold temperatures have been working to facet and break down the buried crust. In sheltered terrain at and below treeline a layer of weak feathery surface hoar or sugary facets may be identified, but this interface has produced little recent avalanche activity. A crust that formed in mid-January is now 50 to 80 cm below the surface. This crust is present right to mountain top on southerly aspects and on all aspects below 1700 m. The remainder of the snowpack is generally well-settled.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm snow may overlie a crust on south facing features which may increase the likelihood of human triggering. Carefully evaluate alpine lines for wind slab hazard and be aware of the potential for loose dry avalanches which could run fast and far.
Minimize exposure to steep planar south-facing slopes - especially if they see sunshine.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 14th, 2019 2:00PM

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