Bulletin d’avalanche

South Rockies

Mar 8 – 9, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Mon
Tue
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort

Points saillants

More snow/rain=More Danger!Forecasted snowfall/rain will be higher in the south of the region. Danger ratings reflect the zones with higher precipitation amounts.South Rockies Blog

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    3–6
    Large loads like cornices and storm slabs in motion have the potential trigger a persistent weak layer that is now buried between 100-170cm deep.
  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–5
    New snow and rain will add to the storm slab sitting on a weak layer buried in early March. Windslabs and cornice growth continue to build in the alpine due to recent SW winds.
  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    Slopes that are becoming rain soaked for the first time will be a particular concern. Loose wet slides are also possible in areas where rain soaked snow has lost its cohesion.

Weather Forecast

The large moist pacific system is poised to reach the South Rockies by Saturday evening bringing increased winds from the south and moderate to heavy precipitation overnight. The southern areas of the forecast region (Elk Valley South and Flathead) will see more precipitation than the north as the system is sticking close to the US/Canada border. Sunday will see continued rain and snow, with a possible dip in the freezing levels as the frontal system passes later in the day. Quieter, spring like weather should prevail for Monday, Tuesday.Ovn Sat: 2-5mm north/15-20mm in the south, with strong south winds as the system arrives. Freezing levels 1600-1800mSunday: 5-20mm with moderate west winds with strong gusts and freezing levels up to 2100m.Monday: No significant precipitation, sunny breaks with light west winds and freezing levels 1700-1800m

Avalanche Summary

Avalanches in clearcuts, road banks, lower angle terrain and non obvious avalanche paths continue to surprise backcountry enthusiasts throughout the region, so consider them carefully in your travel plans as danger ratings rise on Sunday. Avalanches in the region have the potential to run full path. As an example we got a report of an avalanche hitting the road during the day on Friday on Hartley Lake Road.Two recent avalanches on east aspects, size 2.5-3 were noted by the field team and other observers in the Crowsnest pass on Friday.In the Harvey Pass area there was a widespread natural cycle on Thursday with some avalanches up to size 3. Most avalanches are failing at the storm snow interface, but some are initiating or stepping down to the February 10th persistent weak layer, even in surprisingly low angle and gladed terrain.There was a report of a large avalanche in Thursday's cycle hitting the grooming about 4km before the Rolling Hills cabin near Fernie.On Thursday the South Rockies team reported a size 2.5 avalanche out of a north facing chute near Grave Lake that left 6 meters of debris on a logging road, blocking their return to the trucks.

Snowpack Summary

Some areas of the South Rockies (Elk Valley South and Flathead) received Thurday's precipitation as significant rain event below 1500m-1700m, while other areas like the Crowsnest, had dry snow below treeline under the influence of colder air. In areas above 1600m there is approximately 40-70cm of new storm snow sitting on top of the March 2 interface consisting of surface hoar, facets or a crust depending on your aspect and elevation . Forecasted new snow and rain, combined with warm temperatures, will likely create another storm slab avalanche cycle by Sunday. Moderate to strong SW winds will continue to create windslabs in alpine lee features and contribute to the already significant cornice growth..The mid pack still contains a layer of facets and/or surface hoar that is now down between 70-180cm depending on your location in the South Rockies. It is still showing good fracture character on snowpack tests, suggesting that it may be possible for storm slabs to step down to this persistent weakness. Check the South Rockies Blog for the latest snowpack discussion.

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