Avalanche Forecast
Issued: Apr 12th, 2013 10:38AM
The alpine rating is Storm Slabs and Cornices.
, the treeline rating is , and the below treeline rating is Known problems includeThe intensity of Friday night's storm is uncertain. If snowfall amounts are higher than anticipated or if the storm persists throughout Saturday morning, the avalanche danger may be HIGH in the alpine.
Summary
Confidence
Fair - Intensity of incoming weather is uncertain on Friday
Weather Forecast
Overnight Friday and Saturday: Moderate snowfall on Friday night tapering to light snowfall on Saturday / Strong southwest winds switching to moderate and northwesterly / Freezing level at 1200mSunday: Trace amounts of snow with overcast skies / Moderate northeast winds / Freezing level at 1200mMonday: Mix of sun and cloud / Calm winds / Freezing level at 1200m
Avalanche Summary
Natural loose dry avalanches to size 2 ran within Wednesday's storm snow, and a size 2 wind slab was ski cut on a northeast alpine slope just below ridge crest. A size 2 natural slab avalanche was observed in a north facing gully feature at 2100m. The early April interface was the suspected culprit. Although recent snow may be gaining strength, I would expect another round of storm slab activity to occur in response to wind and snow forecast for Friday afternoon.
Snowpack Summary
At upper elevations moderate amounts of recent snow have been shifted into deeper windslabs by steady southwest winds. About 40-75cm below the surface you are likely to find a temperature/sun crust from early April's clear weather. At the same interface you may find a layer of spotty surface hoar on shaded alpine slopes above ~2400m. At lower elevations (below 1600m) rain has saturated the snowpack, and surfaces are either moist or refrozen (temperature depending).Recent snowfall combined with wind have made large cornices bigger and more likely to fail.
Problems
Storm Slabs
Moderate snowfall and strong winds forecast for Friday night will create new storm/ wind slabs. Storm slabs will be particularly touchy in wind-affected terrain.
Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Choose conservative lines and watch for clues of instability.>
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Ongoing wind and snowfall has added to size and fragility to existing cornices. Cornice falls may be destructive by themselves, and may also trigger large avalanches on the slope below.
Pay attention to overhead hazards like cornices.>
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 13th, 2013 2:00PM