Detailed Observation

ObserverAllen Dahl

General Observations

Benzene up to a high point of 1700′ for a couple of laps. 

We noticed two small fresh debris piles initiating from steep terrain on the north face of Benzene. 

Skies were scattered in the morning, becoming overcast near noon, and opening back up to broken skies before sunset.
Car temp sensor read 1*C upon return (near 4pm, at sea level). 
We observed moderate Easterly winds, and witnessed active snow transport. The top 300′ of our skin track had completely filled back in between laps. Flagging on surrounding peaks seemed a bit more Northeasterly.
Small pseudo-cornices along the ridge line had proved to be more reactive following the afternoon winds, exhibiting shooting cracks when weighted. See attached photos.

There is an abundance of loose snow available for transport. It is very low density. Ski penetration was typically ~30cm, but in some areas it was deeper. Even snow that had been obviously redistributed by the winds was very soft with low cohesion.

I dug numerous handpits for quick assessment throughout the day at various elevations and aspects. At 480′ asl I found a thin & weak mf crust ~40 cm below the surface, with faceted grains below. This failed with moderate force. After noticing some cracking at 760′, I dug multiple hand pits (east aspect) and found 5-6mm standing buried surface hoar, just 3 cm above the mf crust/facet combo. Digging frequently, I continued to find this buried surface hoar layer on W, NW, and N aspects, up to 1100′, where it disappeared between pits only about 20 vertical and 50 horizontal feet apart from each other. I did not find the BSH in subsequent pits above this elevation. All handpits that harbored the BSH failed with easy force, except for an isolated location that was actually failing at the crust/facet with easy/moderate force, even though the BSH was present. Handpits above this elevation typically failed with easy/moderate force, on a variety of slightly faceted layers. The obvious crust/facet combo became deeper (~60cm) with elevation gain.

Note: In nearly all handpits, the snow above the failing layer had low cohesion (i.e. was not behaving as a slab), thus I wasn’t particularly concerned about the obvious weak layers in the snowpack. This may change as winds continue and/or the low density snow settles and becomes more cohesive.

Uploaded Images

Weather Observations

Observed Avalanche Activity