Avalanche Forecast
Issued: Nov 20th, 2011 8:46AM
The alpine rating is Wind Slabs, Persistent Slabs and Storm Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Poor - Due to limited field observations
Weather Forecast
Monday: The storm begins. Expect snowfall to increase throughout the day and winds to turn southwest. Freezing levels could reach 1500m, Tuesday: Snow, at times heavy. Continued strong southwest winds and freezing levels peaking at 1700m. Wednesday: Snow tapering through the day, with a bit of a lull late in the day. Southwest winds continue with freezing levels reaching 1200m.I would not be surprised with 80-100cm of new snow within the forecast period.
Avalanche Summary
Avalanche activity has slowed down with the colder temperatures, but recent reports include wind slab avalanches up to Size 2.5 failing on the crust/surface hoar combo that was buried November 9. Some slabs were up to a metre deep and pulled back into low angled terrain on ridges showing incredible propensity for propagation. The critical elevation band for the crust/surface hoar combo is between 1800 and 2050m.
Snowpack Summary
There has been limited new snow in the past couple of days and the colder temperatures have tightened up the storm snow instabilities. The snowpack sits at about 100cm in sheltered locations at treeline, with deeper, wind deposited pockets in the alpine and around ridgeline features. A rain crust, buried November 9 is prominent between 1800m and 2050m and has surface hoar crystals either above, within or slightly below it. This crust/surface hoar combo is buried 40 to 70cm and is the deeper layer of concern.
Problems
Wind Slabs
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 21st, 2011 8:00AM