Avalanche Forecast
Issued: Mar 2nd, 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.
shorton,
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 bigger alpine terrain features.
Summary
Confidence
Moderate - Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.
Weather Forecast
A few weak frontal systems will graze the region this week with sustained mild temperatures.
MONDAY NIGHT: Cloudy, light flurries with trace accumulations of snow, strong west wind, freezing level around 1200 m with alpine temperatures around -5 C.
TUESDAY: Mix of sun and cloud, freezing level climbs from 1200 to 1800 m, moderate to strong west wind, alpine high temperatures around -3 C.
WEDNESDAY: Scattered flurries with 5-10 cm of snow, moderate to strong west wind, freezing level dropping from 1800 to 1300 m, with alpine temperatures dropping to -5 C.
THURSDAY: Mostly sunny, freezing level climbing from valley bottom to 2000 m in the afternoon, moderate southwest wind, alpine temperatures reach 0 C.
Avalanche Summary
No new avalanches were reported on Monday. 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 Mountain Information Network (MIN) report from February 11 and this MIN report on February 9.Â
Snowpack Summary
The South Rockies picked up at about 7 cm of snow over the weekend, followed by strong to extreme wind out of the southwest which has formed thin wind slabs in high elevation terrain, especially that immediately lee of ridge crest.
Under this new snow is a crust that may extend as high as 2300 m on solar aspects. It is present on all aspects to 1700 m. Â
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.Â
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
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Conditions may have improved, but be mindful that deep instabilities are still present.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Wind Slabs
Watch for thin wind slabs immediately lee of ridge crest, especially in more extreme terrain. Also be aware of the potential for cornice failure, large cornices overhang many ridge lines at this time
Aspects: North, North East, East, South East, South.
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 3rd, 2020 4:00PM
