Unpleasant turbulence is one thing. Turbulence which will down a Pa28 is another matter.
There's no mention of any distress message being picked up, and on any likely frequency, on that day, in that area, I'd expect any transmission to be heard by someone, even if from a very low altitude.
I'd expect there would be a radar track for most of the flight, but that won't be public until the accident report is issued.
As regards being able to glide to shore, ditching might be a preferred option with engine failure, but not 2 miles offshore.