Quick report
Observed a natural R1D1 wind slab avalanche on our approach to SE shoulder of Blackmore. Winds were very strong from the S all along the approach through the open meadow corridors. Once on the shoulder itself, winds were blowing strongly from the W, forming large wind drifts on the ridgeline. At around 9600', we measured HS of 175cm, with 55cm of new snow. Generally, visibility was poor, but we saw a few loose snow sloughs along the E face. Noted a major ambient temperature change throughout the day. The snow in the alpine grew denser and heavier, and as we descended, in the exact spot where we saw the wind slab avalanche, we noted roller balls and wet surface snow at 2 pm.
Avalanche
At 8700' on the Blackmore approach in the lowest open meadow, we witnessed a natural R1D1 soft wind slab avalanche that broke during a large gust of wind. The top was actively being loaded by strong winds, swirling from the S. The crown was a few inches deep, ~10' wide and ran ~175'.