Vern pointed out that you can see the scattered light moving around, by looking at the video cameras. 

Attached are 2 videos captured from our digital cameras.  They start within about 1 sec of eachother, but they're not exactly the same times.  On the PR3 camera, the motion is very obvious.  On the PRM camera, you can kind of see some of the scatter in the center of the image changing with a similar period as that of PR3. 

I also tried to take a 1 min video with my phone of the analog SRC camera that is on the front small TV display where you can kind of see some scatter moving, particularly in the center vertical "bar" of the screen. But, the quality isn't so good and it's hard to see in the video-of-a-video.  But, it seems like there is some motion of the scatter pattern there too.

Calibrated (in m/rtHz) ground displacements and St1 & St2 displacement for the ITMX ISI, comparing now and 12 hours ago. First plot shows the X and Z ground displacments, solid lines are from 12 hours ago, dashed are from the last half hour. The peak frequency has moved down in frequency, but gone up about an order of magnitude. Second plot shows the St1 and St2 displacements, solid red and blue are from 12 hours ago, pink and light blue are from the last half hour. It looks like the sensor correction not doing quite as good as I had hoped when we worked on this during the summer, there is room for improvement here.

If we can't lock due the ground motion, operators can try some of the USEISM configurations in SEI_CONF, probably USEISM_MOD_WIND given the 20mph winds.

I'm opening a work permit to test a new configuration, using some narrow band sensor correction on ST2, keeping the WINDY configuration on ST1. I'll leave some instructions with the operators, but they can call me if they have questions or need some guidance.