The attenuation they are referring to should be the radar's attenuation.
Probably due to very heavy rain.
I noticed that observation too. Don't recall seeing it before.

Nicole Mitchell, of The Weather Channel, is a US Air Force Meteorologist, and was flying on one of the missions Wednesday night. I heard her doing a phone interview early Friday morning. She stated that normally they encountered turbulence just prior to entering the eyewall.
However, during the flight she referred to, they encountered turbulence, lightning and hail.
I don't know if she is flying tonight or not. As the aircraft are rotating flights.

Here's another Concentric Eyewall link.
http://www.aoml.noaa.gov/hrd/tcfaq/D8.html