Avalanche Forecast
Issued: Feb 29th, 2020 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.
ghelgeson,
Avalanche Canada
The warm to cold temperature trend has helped to stabilize the storm snow, but we still have a lingering deep persistent slab problem in play which makes it impossible to have 100% confidence, especially in alpine terrain features.
Summary
Confidence
Weather Forecast
Warmer funky weather is with us for the forecast period.
SATURDAY NIGHT: Freezing level returning to valley bottom, light variable wind, 1 to 5 cm of snow possible.
SUNDAY: Broken cloud cover in the morning with some afternoon clearing, freezing level beginning at valley bottom rising to 1500 m during the day, light west/southwest wind, no significant precipitation expected.
MONDAY: Clear skies at dawn building to scattered cloud cover in the afternoon, freezing level beginning at valley bottom rising to 1900 m during the day and then staying there until Thursday morning, light west wind at lower elevations, strong northwest wind at mountain top, no precipitation expected.
TUESDAY: Scattered cloud cover, freezing level holding around 1900 m, moderate to strong west/southwest wind, no significant precipitation expected.
Avalanche Summary
One of our field team members got out for a flight Friday, and she found a slab avalanche on a steep east/southeast facing alpine feature. Aside from that and a bit of loose wet activity on solar aspects, there has been little reported recent avalanche activity.
The most recent deep persistent slab activity we know about is described in this MIN report from February 11 and this MIN report on February 9.
Snowpack Summary
The 10 to 35 cm of snow from Sunday/Monday was absolutely hammered by wind Wednesday as evidenced in this MIN submission. Wind was strong enough to get into below treeline features even. Then it got quite warm Friday, the freezing level got to at least 2300 m. The beat up old snow got quite warm and a crust is likely forming on the surface now.
A thick rain crust sits 40-80 cm below the surface and can be found up to 2100 m. Avalanche activity was last observed at the faceting interface between this crust and overlying snow on February 17.
The mid-pack is well settled and strong, but the base of the snowpack contains basal facets that are most prominent in shallow rocky start zones.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Conditions may have improved, but be mindful that deep instabilities are still present.
Problems
Wind Slabs
The recent warm to cold temperature trend has made these less likley to trigger, but carefull with wind slabs at the highest elevations, especially in extreme terrain.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
Weak snow at the bottom of the snowpack hasn't gone away unfortunately. Cornice failures become more likely during these kinds of conditions and a failing cornice could be the perfect trigger for the deep persistent slab. Human triggering would be most likley around steep rocky terrain features, or anywhere the snowpack is thin and weak.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 1st, 2020 5:00PM
