Big Dawgs and Big weak layers at Dickey

We went to Dickey Lake to document the recently observed persistent slab.

• Widespread weak layer growth at the surface! On shady aspects, we found large surface hoar (1-2 cm) from valley up to ~5200’, small-grained surface hoar and facets (1 mm) to ~5700’, and small-grained facets to 7200’ and likely beyond.  Sun crusts were forming on southerly aspects.  All of this is over a rain crust at mid and lower elevations. 
• The avalanche above Dickey Lake was impressively large, D3.5. The debris collapsed the ice on Dickey Lake, and was up to 12-15’ deep across the lake. The crown was a 4.5’ thick hard slab that failed on a faceted sun crust (Dec 9 or Thanksgiving interface, previously documented here).  It appeared to be triggered by a cornice fall onto a shallow, rocky area.  There was no new snow above the bed surface, so it must have failed after the storm ended, sometime around Thursday, 1/10. The terrain averaged around 35 degrees, but it pulled into 30 degree terrain. The slope was planar at the start zone rolling into convex with a pronounced rock band at the rollover. 
• Stability tests at the crown produced no notable results.  2 other pits in the area produced a mix of unreactive and hard, propagating results at the same interface. No obvious signs of instability today, and no wind.