Surface hoar observations in the Yuba Pass area.

I toured south from Yuba Pass to Lincoln Ridge this morning to have a look at surface hoar (SH) and compare it to my SH observations in this area on 1/26. Large SH up to 30 mm was still present. I found it upright and intact in open, shaded, wind protected areas below treeline. A few of these areas were small slope avalanche terrain.

Up in the obvious near treeline NE aspect avalanche terrain along Lincoln Ridge, I noted widespread SH, similar in distribution as I had seen it on 1/26. At casual glance this 8 to 10 mm SH appeared as if it might still be upright, but on closer inspection it was clearly knocked over and slightly melted. I noted this knocked over SH in all of the more significant near treeline avalanche start zones along the ridgetop.

Thinking about tomorrows expected snowfall, the knocked over SH still presented as a weak old snow surface. It may still be able to contribute to instability, albeit potentially to a lesser extent than on slopes where the SH remains upright and intact.