March 5, 2015

Observations – Canyon Road – Peak 3 to 4

3:45-6:45pm

Obvious signs of instability:

Weather:

  • Mostly cloudy to obscured skies with intermittent rain showers at the lower to mid elevations and snow showers in the upper elevations (rain-snow line ~2000′)
  • Temps in the mid to upper 30s at mid elevations cooling to mid 20s in the upper elevations
  • Light southerly breeze

Surface conditions:

  • Mostly supportable (1F+ or harder) wind slab west facing Peak 3 bowl with areas of subtle sastrugi, exposed old and hard crust, and some blown-in moist and dense powder (top ~300′ and in the sheltered lower gully)
  • Supportable to slightly breakable (1F+ or harder) wind slab and thin (1-2cm) melt-freeze crust WSW Peak 4 with moist and dense powder for the top ~200-300′

Discussion:

Peak 4’s WSW face and gully had an interesting wind slab/melt-freeze crust at the surface.  This is expected to provide a relatively slick sliding surface for new snow, but bonding should nonetheless be facilitated by the warm temps accompanying Thursday night’s snowfall and the subtle melt-freeze crust at the surface still being somewhat moist and not completely refrozen.

Stress from a possible 1’+ of new snow Thursday night through Saturday morning, along with wind loading from the stronger winds expected to accompanying the heavier snowfall Friday night to Saturday morning will raise the persistent slab concern found mid snowpack where crust-facet combos exist.  Storm slabs are also expected to develop and will be more problematic on leeward aspects, especially in areas with exposed hard crusts.

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