PST (Propagation Saw Tests) tend to have a higher "false stable" ratio than ECTs (Extended Column Tests) but may be preferable when one has a deeper weakness of concern.
Eric Knoff (retired Snowbird) and current Gallatin NF Avalanche Center forecaster wrote a paper on horizontal pit-wall PSTs and published it at this fall's ISSW. His data indicate that CPSTs share similar critical cut lengths as standard PSTs, with 75% of critical cut lengths falling within 10 cm of each other. Something to consider as they're much more efficient to conduct, especially in a standard ECT pit wall.
As you'll see in the side-by-each video, fairly weak facets nearly 80 cm down preserved from mid-Dec 17/18 demonstrate difficult to initiate but good propagation. Poor structure? Sorta. A current avalanche problem? Not at the top of the list. Possible in very thin, shallow snowpack areas (Lambs, Aire, etc) with new loading. Another factor would be the type of trigger - "may be reactive to heavy loads - large cornice fall, multiple machines on the slope, step down avalanche."
Video
Pockets of Moderate for windslab today; perhaps more widespread Moderate tomorrow.
