This interesting gull was photographed by a non-birder in the Bet She'an Valley, Israel on October 11th. At this time of the year armenicus is by far the commonest gull in Israel.
This seems to be a 2cy bird, but the yellow legs are pretty striking.
My first impression was of armenicus (small head, bill size and proportions) but this extremely long rear and heavy head markings are wrong for armenicus in this plumage. Head and neck streaking somewhat reminds argentatus group, but remember that aregentatus has been recorded only once in Israel. Shape and proportions almost remind of canus group. Unfortunately no images of open wing.
Your comments are welcome.