Avalanche Forecast
Issued: Mar 22nd, 2013 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs.
garth lemke,
Parks Canada
Cornices are large and looming. Give them a wide berth as their failure has the potential to trigger deep instabilities. Trigger ability increases with daytime heating and sun.
Summary
Weather Forecast
The weekend will have flurries, clouds intermixed with sun, diurnal fluctuation of cold nights and freezing level 1000m or higher by the afternoon, and calm to light North winds. Monday and later will have sunny conditions, freezing level 1500m or higher, and trending increasingly warmer each afternoon.
Snowpack Summary
The surface storm and wind slab have melded with the snowpack making a persistent slab in alpine and treeline locations on a variety of aspects. 90cm has fallen since March 13 and was moved around by variable winds since then. At treeline in south facing terrain, the snow rests on a suncrust 80 cm deep. The snowpack is generally supportive.
Avalanche Summary
A size 3 triggered by cornice failure in the afternoon heat, scrubbed to ground, 2m crown, and ran full path occurred yesterday in the Shangrila area. A helicopter flight Tuesday revealed a significant avalanche cycle occurred on N to NE alpine slopes to size 3 and on terrain as low as 25 degrees triggered by wind loading and sunny skies.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
Deep Persistent Slabs
The 90cm of snow since March 13 has generally melded with the snowpack making for a deep persistent slab. North and South winds have this present on a variety of aspects overlying weak basal facets. Cornice failures can trigger this in a big way.
Choose conservative lines and watch for clues of instability.Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 23rd, 2013 4:00PM
