Looking into it, I can't find too much specific info. Just this from Google Search Liaison:
"Tomorrow, we are releasing a broad core algorithm
update, as we do several times per year. It is called the June 2019
Core Update. Our guidance about such updates remains as we’ve covered
before. Please see this tweet for more about that:https://t.co/tmfQkhdjPL— Google SearchLiaison (@searchliaison
Nothing
special or particular "big." It's the usual type of core updates that
we regularly do. We just wanted to be more proactive. Rather than people
scratching their heads after-the-fact and asking "hmm?," we thought it
would be good to just let folks know before it rolled out. — Danny Sullivan (@dannysullivan)June 2, 2019
(There is another roll-out presently underway and hitting data centers dealing with multiple returns from the same site.)
“June 2019 Core Update” is its official name, in case you want to search for more details.
So the pre-announcement wasn't b/c it's some major update in a category of significance all its own, but rather Google being more transparent and communicative. Probably the start of a new trend of pre-announcement announcements? Just as long as SEOs don't clamor for a pre-pre-announcement, all seems well.
violafrolova
Moscow
Comments
"Tomorrow, we are releasing a broad core algorithm update, as we do several times per year. It is called the June 2019 Core Update. Our guidance about such updates remains as we’ve covered before. Please see this tweet for more about that:https://t.co/tmfQkhdjPL— Google SearchLiaison (@searchliaison
Nothing special or particular "big." It's the usual type of core updates that we regularly do. We just wanted to be more proactive. Rather than people scratching their heads after-the-fact and asking "hmm?," we thought it would be good to just let folks know before it rolled out. — Danny Sullivan (@dannysullivan) June 2, 2019
List of Domains Losing Visibility in June 2019 Update. Anyone see any correlation?