Bathtub Ring Effect in the passes?

I've read some reports of buried surface hoar in the passes. I'm just wondering if this might be due to the "bathtub ring effect" as described by Tremper and others, namely the presence of surface hoar at the upper inversion level. We had some strong inversions this week which might account for this. Outside of the passes the inversion layer was much lower (shallower) so the elevation in these areas could be too low, i.e. too little snowpack less than 3,000 feet to be of consequence.

It will be interesting to see how this layer evolves or if it becomes a moot point due to rain and a strong avy cycle. Of particular interest to judge the staying power and danger of this layer would be to note the size of the surface hoar crystals (larger crystals may tend to persist longer?) and their location in regards to the mid-November rain crust. Crystals near a crust may tend to be problematic for awhile as they don't stabilize by embedding into softer adjacent layers and ,of course, crusts provide and excellent bed surface for a sliding layer.

Does anyone have field reports regarding the size and location of the SH crystals in the snowpack in terms of depth and surrounding layer properties? Also, has anyone observed buried surface hoar outside of the passes? And finally, what do others with weak layers on the brain think about this "bathtub hypothesis"?

Absolutely.. but after going up to rock mountain last weekend there wasn't that much snow at the mid elevation where the bathtub ring typically occurs.

Furthermore, I think north faces never heated up enough during the inversion to melt hoar frost and I personally saw hoarfrost on rock mountain in wind sheltered areas.

Hopefully this storm cycle is a good reset button for hoarfrost and that ice layer in the alpine.

I know I found buried surface hoar on Friday at Stevens in the Grace Lakes area (south side of pass at 4450'), about 15" down or so. NWAC Pro-Observer Dallas Glass found the same on the north side of the pass. You'd need more examples at other elevations to support the ring effect theory but iut's certainly possible.

Recent trip reports from the passes seem to show propagation on weak layers near the mid-November crust. I suspect this could be that surface hoar due to the inversion. In other areas away from the passes, I believe that it may have gotten too warm to support surface hoar development (or just melted any new s.h.). It would be interesting to check telemetry to verify the height of the inversion outside of the passes during this time period.

Just an FYI stating the obvious in case anyone trips across this post later:

This November SH layer is probably now a moot point as of 12/9/15. Extensive rain has either a: saturated and melted the SH layer or b: caused a natural avalanche to release on the SH or c: the layer is now bridged over by two feet of refreezing wet snow.

Agreed. NWAC still listed as a concern yesterday morning on all aspects and elevations on the I-90 to Columbia area but I'm guessing the rain cleaned it out by today, particularly since they don't have it listed. There's a reason they call them persistent weak layers but hopefully the rain saved us from some season long concern.

-Ryan